Ultrafast Phenomena XIV: Proceedings of the 14th International Conference, Niigata, Japan, July 25--30, 2004

Springer Series in

CHEMICAL PHYSICS

79

Springer Series in

CHEMICAL PHYSICS Series Editors: A. W. Castleman, Jr. J. P. Toennies

W. Zinth

The purpose of this series is to provide comprehensive up-to-date monographs in both well established disciplines and emerging research areas within the broad fields of chemical physics and physical chemistry. The books deal with both fundamental science and applications, and may have either a theoretical or an experimental emphasis. They are aimed primarily at researchers and graduate students in chemical physics and related fields. 65 Fluorescence Correlation Spectroscopy Theory and Applications Editors: R. Rigler and E.S. Elson 66 Ultrafast Phenomena XII Editors: T. Elsaesser, S. Mukamel, M.M. Murnane, and N.R Scherer 67 Single Molecule Spectroscopy Nobel Conference Lectures Editors: R. Rigler, M. Orrit, T. Basche 68 Nonequilibrium Nondissipative Thermodynamics With Application to Low-Pressure Diamond Synthesis ByJ.-T.Wang 69 Selective Spectroscopy of Single Molecules By I.S. Osad'ko 70 Chemistry of Nanomolecular Systems Towards the Realization of Molecular Devices Editors: T. Nakamura, T. Matsumoto, H. Tada, K.-I. Sugiura 71 Ultrafast Phenomena XIII Editors: D. Miller, M.M. Murnane, N.R. Scherer, and A.M. Weiner 72 Physical Chemistry of Polymer Rheology By J. Furukawa

73 Organometallic Conjugation Structures, Reactions and Functions of d-d and d-TT Conjugated Systems Editors: A. Nakamura, N. Ueyama, and K. Yamaguchi 74 Surface and Interface Analysis An Electrochmists Toolbox By R. Holze 75 Basic Principles in Applied Catalysis By M. Baerns 76 The Chemical Bond A Fundamental Quantum-Mechanical Picture ByT. Shida 77 Heterogeneous Kinetics Theory of Ziegler-Natta-Kaminsky Polymerization ByT.Keii 78 Nuclear Fusion Research Understanding Plasma-Surface Interactions Editors: R.E.H. Clark and D.H. Reiter 79 Ultrafast Phenomena XIV Editors: T. Kobayashi, T. Okada, T. Kobayashi, K.A. Nelson, S. De Silvestri

Takayoshi Kobayashi Tadashi Okada Tetsuro Kobayashi Keith A. Nelson Sandro De Silvestri (Eds.)

Ultrafast Phenomena XIV Proceedings of the 14th International Conference, Niigata, Japan, July 25-30, 2004

With 577 Figures

Spri ringer

Professor Takayoshi Kobayashi

Professor Keith A. Nelson

University of Tokyo, Department of Physics Kongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan

MIT Room 6-235 Massachusetts Avenue Cambridge, MA 02139, USA

-j-j

Professor Tadashi Okada Toyota Physical and Chemical Research Institute Nagakute, Aichi 480-1192, Japan

ProfeSSO Sandro De Silvestri Politecnico di Milano, Dipartimento di Fisica Piazza L. da Vinci 32,20133 Milano, Italy

Professor Tetsuro Kobayashi Osaka University, Engineering Science Machikaneyama-Cho 1-3, Toyonaka Osaka 560-8531, Japan

Series Editors: Professor A. W. Castleman, Jr. Department of Chemistry, The Pennsylvania State University 152 Davey Laboratory, University Park, PA 16802, USA

Professor J.P. Toennies Max-Planck-Institut fiir Stromungsforschung, Bunsenstrasse 10 37073 Gottingen, Germany

Professor W. Zinth Universitat Miinchen, Institut fiir Medizinische Optik Ottingerstr. d-j^ 80538 Miinchen, Germany

ISSN 0172-6218 ISBN 3-540- Springer Berlin Heidelberg New York Library of Congress Control Number: 2004116005 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. DupUcation of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. Springer Berlin Heidelberg New York a member of BertelsmannSpringer Science-hBusiness Media GmbH springeronline.com © Springer-Verlag Berlin Heidelberg 2005 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Typesetting: Camera-ready copy by the authors Cover concept: eStudio Calamar Steinen Cover production: design & production GmbH, Heidelberg Printed on acid-free paper

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Preface

This volume is a collection of papers presented at the Fourteenth International Conference on Ultrafast Phenomena held in Niigata, Japan from July 25-30, 2004. The Ultrafast Phenomena Conferences are held every two years and provide a forum for discussion of the latest results in ultrafast optics and their applications in science and engineering. A total of more than 300 papers were presented, reporting the forefront of research in ultrashort pulse generation and characterization, including new techniques for shortening the duration of laser pulses, for stabilizing their absolute phase, and for improving tenability over broad wavelength ranges, output powers and peak intensities. Ultrafast spectroscopies, particularly time-resolved X-ray and electron diffraction and two-dimensional spectroscopy, continue to give new insights into fundamental processes in physics, chemistry and biology. Control and optimization of the outcome of ultrafast processes represent another important field of research. There are an increasing number of applications of ultrafast methodology in material diagnostics and processing, microscopy and medical imaging. The enthusiasm of the participants, the involvement of many students, the high quality of the papers in both oral and poster sessions made the conference very successful. Many people and organizations made invaluable contributions. The members of the international program committee reviewed the submissions and organized the program. The staff of the Optical Society of America deserves special thanks for making the meeting arrangements and running the meeting smoothly. We thank the Optical Society of America for sponsorship, and also acknowledge support from The Physical Society of Japan, Japan Society of Applied Physics, Niigata Prefecture, Niigata Visitors & Convention Bureau, Niigata University, Japan National Tourist Organization and Inoue Foundation for Science. Tokyo, Japan Osaka, Japan Osaka, Japan Cambridge, USA Milano, Italy September 2004

Takayoshi Kobayashi Tadashi Okada Tetsuro Kobayashi Keith A. Nelson Sandro De Silvestri

V

Preface by a chair of Local Organizing Committee

The Fourteenth International Conference on Ultrafast Phenomena was held during Jul. 25-30, 2004 in Niigata. Niigata is distinguished for being one of only five international ports opened in 1868 when Japan resumed contact with other countries after nearly 250 years of self-imposed isolation. Since that time, Niigata has developed into one of most important modern international ports in Japan. In this sense the city is appropriate for the International Conference on Ultrafast Phenomena to be held. Since this meeting is usually held twice in the USA and once outside of the country of three years even though there were exceptions, the style and organization of the conference were sometimes quite different from the ones held in the USA. Because of the time shift and also of differences in the way of organization of conference place, we has experienced some complicated difficulties several times but finally we could find to solve the problems after various efforts to disentangle such kinds of problems. This is a very good experience of having the conference outside of the USA and I hope it will be very useful to utilize the knowledge in future meetings. Personally I have attended all of the conferences of this series starting from the first Topical Meeting of Picosecond Phenomena organized by Drs. Charles V. Shank, Erich P. Ippen, and late Stanley L. Shapiro at Hilton Head in South Carolina in 1978, third Picosecond Phenomena Meeting at GarmischPartenkirchen Germany and the fourth Ultrafast Phenomena at Monterey in California, and 13^^ UP at Vancouver in 2002 including the conferences in between. Until the 13^^ UP conference, there were four people who had attended all of these conferences, Prof. R. M. Hochstrasser, Erich P. Ippen, Graham Fleming, and myself. In the last meeting held in Niigata the last three among the four have left being the regular visitors. It is amazing to see the development made in these 26 years namely more than a quarter of century shown in the meeting and it is surprising to see that this conference is still acting as the place of presentation of the frontier activities of the field. Even more delightful feature I found in the conference is that three were so many new young scientists attended and gave nice talks and presented excellent works at poster sessions. I am also extremely happy to be able to have many scientists both senior and young came to Japan from very far. I am really hoping to see even more developed and active research presentations in future meetings of the Ultrafast Phenomena. General Chair of Local Organizing Committee Takayoshi Kobayashi

VII

Contents

Part I Generation and Measurements Single-Cycle Optical Pulse Generation D.R. Walker, M. Shverdin, D. Yavuz, G.-Y. Yin, S.E. Harris

3

Toward a Terawatt Few-Optical-Cycle Driver Laser for Attosecond Spectroscopy N. Ishii, R. Butkus, A. Baltuska, E. Goulielmakis, M. Uiberacker, R. Kienberger, T. Fuji, V.S. Yakovlev, V. Smilgevicius, R. Danielius, A. Piskarskas, F. Krausz

8

2.8-fs Clean Single Transform-Limited Optical-Pulse Generation and Characterization K. Yamane, T. Kito, R. Morita, M, Yamashita

13

Coherent Amplification of Femtosecond Pulses with Passive Enhancement Cavities RJ. Jones, L.-S. Ma, J. Ye

16

Temporal and Spatial Pulse Compression in a Nonlinear Defocusing Material N. C. Nielsen, T. Honer zu Siederdissen, J. Kuhl, M. Schaarschmidt, J. Forstner, A. Knorr, S. W. Koch, H. Giessen

19

Intense CEO-Stabilized Few-Cycle Laser Pulses from Supercontinuum Generation in Filaments J. Biegert, C.P. Hauri, W. Komelis, A. Heinrich, F.W. Helbing, A. Couairon, A, Mysyrowicz, U. Keller

22

Generation of Ultra-Broadband High Energy Pulses without External Amplification A. Fuerbach, A. Fernandez G., T. Fuji, H. Mayer, P. Dombi, F. Krausz, A. Apolonski

25

Sub-10 fs Multi-mJ Ti:Sapphire Laser System with a Pressure-Gradient Hollow Fiber Y. Oishi, A. Suda, F. Kannari, K. Midorikawa

28

IX

Generation of 14-fs Ultrashort Pulse in All Fiber Scheme by Use of Highly Nonlinear Hybrid Fiber T. Hori, N. Nishizawa, T. Goto

31

High Peak Power Ultrashort Pulse Generation Using All-Fiber Chirped Pulse Amplification System with Small Core Multimode Fiber J. Takayanagi, N. Nishizawa, H. Nagai, M. Yoshida, T. Goto

34

Carrier-Envelope Phase Fluctuations of Amplified Laser Pulses Transmitted through Neon-Filled Hollow Fiber for Pulse Compression A. Ishizawa and H. Nakano

37

Temporal Self-Compression of Intense Femtosecond Pulses Propagating in Argon-Filled Hollow Waveguides N. Wagner, E.A. Gibson, S. Backus, M.M. Mumane, H.C. Kapteyn, LP. Christov

40

Stimulated Brillouin Scattering in Ultrahigh-Speed Femtosecond Soliton Pulse Compression with a DispersionDecreasing Fiber T. Hirooka, S. Ono, K.-L Hagiuda, M. Nakazawa

43

Control of the Spectral Broadening of Tens-Milli-Joules Laser Pulses in an Argon-Filled Hollow Fiber Using a Conjugate Pressure Gradient M. Nurhuda, A. Suda, K. Midorikawa

46

Microstructured Fiber Feedback Pulse Compression to Few Optical Cycles M. Adachi, K. Yamane, R. Morita, M. Yamashita

49

Spectral-Temporal Soliton Dynamics Analysis Near Second Zero-Dispersion Point in Photonic Crystal Fibers A, Efimov, A.J. Taylor, F.G. Omenetto, N. Joly, D.V. Skryabin, J.C. Knight, W.J. Wadsworth, P.S.J. Russell

52

Generation of Rotational Raman Emissions and SelfCompressed Femtosecond Pulses in a Hydrogen Gas S. Zaitsu, Y. Kida, T. Imasaka

55

Spectral Broadening of 50 Milli Joule Laser Pulses in a Neon-Filled Herriot Multiple-Pass Cell (MPC) M. Nurhuda, A. Suda, K. Midorikawa

58

X

CEO Phase Preservation in Chirped-Pulse Optical Parametric Amplification of 17.3-fs Pulses J. Biegert, C.P. Hauri, P. Schlup, W. Kornelis, F,W. Helhing, U. Keller, G. Arisholm

61

Long-Term Stabilization and Control of CEP of Idler from NOPA S. Adachi and T. Kobayashi

64

Experimental and Theoretical Study of a Visible Noncollinear Optical Parametric Amplified Pulse with 200 THz Bandwidth X Fang and T. Kobayashi

67

Tunable Wavelength Pulse Shaping of Visible N O P A Outputs with an Acousto-Optic Programmable Dispersive Filter D. Kaplan, P. Toumois, B. Chatel, A. Monmayrant

70

Broadband High Power Optical Chirped Pulse Amplification N. Ishii, R. Butkus, A. Baltuska, V. Smilgevicius, R, Danielius, A. Piskarskas, F. Krausz

73

Mid-Infrared Femtosecond Pulse Generation by Optical Parametric Amplification under Broadband Q P M Condition S. Ashihara, M. Ikeda, T. Shimura, K. Kuroda

76

Achromatic Second Harmonic Generation: Tunable Ultraviolet Pulses with Sub-10 fs Duration P. Baum, S. Lochbrunner, E. Riedle

79

Ultrabroad-Band Noncollinear Optical Parametric Amplification in Some N e w Nonlinear Optical Crystals P. Kumbhakar and T. Kobayashi

82

Design of Multilayer Mirrors for the Refiection of Sub-Femtosecond Pulses in the X U V Spectral Region A.S. Pirozhkov, H. Daido, S. V. Bulanov, E.N. Ragozin

85

Route to Design Electric Fields of Optical Pulses: A Combination of a Pulse Shaper and a Carrier-EnvelopePhase Stabilized Chirped-Pulse Amplifier System M. Kakehata, H. Takada, Y. Kobayashi, K. Torizuka, K. Nishijima, H. Takamiya, T. Homma, H. Takahashi

88

Towards Electric Field Reconstruction Using Coherent Transients in a Two-Level System A. Monmayrant, B. Chatel, B. Girard

91

XI

Spatiotemporal Determination of the Absolute Phase of Few-Cycle Laser Pulses F. Lindner, M. Schdtzel, G. Paulus, H. Walther, A. Baltuska, E. Goulielmakis, M. Lezius, F.c Krausz

94

Spatial Chirp and Pulse-Front Tilt in Ultrashort Laser Pulses and Their Measurement 5. Akturk, X. Gu, E. Zeek, R. Trebino

97

Principal Control Analysis: Gaining Insight from Feedback Learning Algorithms J.L. White, B.J. Pearson, P.H. Bucksbaum

100

Population-Split Genetic Algorithm for Phase Retrieval of Ultrafast Laser Pulses C.-W. Chen, S.-F. Shu, C.-K. Lee, C.-L. Pan

103

Eight-Frame Observation of Propagation Behavior of 0.49-mJ, 45-fs Optical Pulses Generated by a 1- kHz Laser System M. Fujimoto, S.-L Aoshima, Y. Tsuchiya

106

Self-Referenced Measurement of the Complete Electric Field of Ultrashort Pulses in Time and Space P. Gabolde, S. Akturk, R. Trebino

109

Pulse-Measurement Challenges at 1.5 Microns: Several-Cycle Pulses and Several-Element Devices S. Akturk, M. Kimmel, R. Trebino, S. Naumov, E. Sorokin, LT. Sorokina

112

Single-Shot Phase Measurement by Spectral Phase Interferometry Using a Streak Camera T. Akagawa, K. Misawa, R. Lang

115

FROG Measured 185 fs Pulses Generated by Down-Chirped Dispersion-Managed Breathing-Mode Semiconductor Laser B. Resan, L. Archundia, P.J. Delfyett

118

Direct Measurement of the Group Delay Dispersion of Ultrashort Pulses Utilizing Molecular Vibrations P.J. Rizo and T. Kobayashi

121

Spatially Encoded Spectral Interferometry for Complete Characterisation of Attosecond X U V Pulses E. Cormier, LA. Walmsley, E.M. Kosik, L. Corner, L.F. DiMauro. . . . 124

XII

Spatially Encoded Spectral Interferometry for Complete Characterization of Ultrashort Pulses E.M. Kosik, A.S. Radunsky, LA. Walmsley, C. Dorrer

, . . 127

Full Characterization of Ultraviolet and Visible 10-fs Pulses with Zero-Additional-Phase SPIDER P. Baum, S. Lochhrunner, E. Riedle

130

Direct Visualization of Transient Absorption by Real-Time Pump-Probe Imaging Spectroscopy A^. Furukawa, C.E. Mair, V.D. Kleiman, J. Takeda

133

Part II Strong Fields and High Order Harmonics Dynamic Molecular Imaging P.B, Corkum

139

Femtosecond Electron Diffraction: Towards Making the "Molecular Movie" J.R. Dwyer, R.E. Jordan, B.J. Siwick, C.T. Hebeisen, R.J. Dwayne Miller

144

Absolute Displacement Interferometry of Ultrafast Laser-Produced Plasma Expansion G. Rodriguez, S.A. Clarke, A.J. Taylor

149

Electron Acceleration through Spatiotemporal Shaping of Ultrashort Light Pulses D.H. Torchinsky, T. Feurer, K.A. Nelson

152

Mapping Attosecond Electron Wave Packet Motion H. Niikura, D.M. Villeneuve, P.B. Corkum

155

Quasi-Monoenergetic Electron Beam Generation in Laser-Driven Plasma Acceleration E. Miura, K. Koyama, M. Adachi, S. Kato, Y. Kwada, S. Masuda, T. Nakamura, N. Saito, M. Tanimoto

158

Control of Multiphoton Ionization Processes in Aligned 12 Molecules by Optimizing Time-Dependent Polarization of Femtosecond Pulses T. Suzuki, S. Minemoto, T. Kanai, H. Sakai

161

Tomographic Imaging of Molecular Orbital with High Harmonic Generation J. Ratani, J. Levesque, D. Zeidler, M. Spanner, P. B. Corkum, D.M. Villeneuve

164

XIII

Femtosecond Infrared Vibrational U p - P u m p i n g of Liquid Phase W(CO)6 T.L Witte, M.C. Motzkus, K.L. Kompa, J.S. Yeston, E.J. Heilweil

167

Ultrafast X-Ray Diffraction K. Sokolowski-Tinten, C. Blome, J. Blums, U. Shymanovich, M. Nicoul, A. Cavalleri, A. Tarasevitch, M. Horn-von Hoegen, M. Kammler, D. von der Linde

170

Quasi-Phase M a t c h i n g of High H a r m o n i c G e n e r a t i o n in t h e "water window" Soft X-Ray Region E.A. Gibson, A. Paul, S. Backus, R. Tohey, M.M. Murnane, H.C. Kapteyn, LP. Christov

175

A d a p t i v e Engineering of Coherent Soft X-Rays T. Pfeifer, D. Walter, C. Winterfeldt, C. Spielmann, G. Gerber

178

G e n e r a t i o n of Strong Soft X-Ray Field Based on H i g h - O r d e r Harmonics H. Mashiko, A. Suda, K. Midorikawa

181

G e n e r a t i o n of Sub-4-fs High H a r m o n i c Pulses a n d T h e i r Application t o t h e Above-Threshold Ionization T. Sekikawa, A. Kosuge, T. Kanai, S. Watanabe

184

Coherent Imaging of Laser-Plasma Interactions Using High-Harmonic E U V Light X. Zhang, D. Raymondson, A.R. Libertun, A.J. Paul, M.M. Murnane, H.C. Kapteyn, Y. Liu, D.T. Attwood

189

High-Order H a r m o n i c Generation from Argon Ions u p t o 250 eV E.A. Gibson, A. Paul, N. Wagner, S. Backus, M.M. Murnane, H.C. Kapteyn, LP. Christov

192

High-Order H a r m o n i c Generation from Femtosecond Laser-Aligned Molecules K. Miyazaki, M. Kaku, K. Masuda, G. Miyaji

195

Efficient G e n e r a t i o n of High-Order Sum a n d Difference Frequencies in t h e X U V Region by Combining a Weak, Longer-Wavelength Field Y. Nomura, T. Kanai, S. Minemoto, H. Sakai

198

Effects of Target Condition on Solid Surface H a r m o n i c s in t h e E x t r e m e Ultraviolet R a n g e T. Ozaki, J.-C. Kieffer, H. Nakano, A. Ishizawa

201

XIV

Control of t h e Frequency C h i r p R a t e of High H a r m o n i c Pulses J. Biegert, M. Bruck, C.P, Hauri, A. Heinrich, F.W. Helhing, W. Kornelis, P. Schlup, U. Keller, R. Lopez-Mart ens, J. Mauritsson, P. Johnsson, K. Varju, A. L'Huillier, M. Gaarde, K.J. Schafer

204

Wavefront Control in High Harmonics G e n e r a t i o n w i t h Fewa n d Many-Optical-Cycle Laser Pulses P. Villoresi, S. Bonora, M. Pascolini, L. Poletto, C. Vozzi, G. Sansone, S. Stagira, M. Nisoli

207

Phase-Driven Strong-Field Processes in t h e Multi-OpticalCycle Regime G. Sansone, S. Stagira, C. Vozzi, M. Pascolini, L. Poletto, P. Villoresi, G. Tondello, S. De Silvestri, M. Nisoli

210

Bright High-Order H a r m o n i c G e n e r a t i o n at 13 n m a n d Coherence M e a s u r e m e n t H.T. Kim, I.J. Kim, V. Tosa, Y.S. Lee, C.H. Nam

213

Attosecond P u l s e G e n e r a t i o n During t h e Laser Pulse Reflection at t h e P l a s m a - V a c u u m Interface A.S. Pirozhkov, H. Daido, S. V. Bulanov

216

Energetic P r o t o n a n d D e u t e r o n G e n e r a t i o n from a Microporous Polytetrafluoroethylene Film w i t h D e u t e r a t e d Polystyrene Using a 2.4-TW Table-Top Laser H. Takahashi, S. Okihara, S. Ohsuka, M. Fujimoto, S. Okazaki, T. Ito, S. Aoshima, Y. Tsuchiya

219

High-Energy P r o t o n s E m i t t e d from a P o l y m e r - C o a t e d M e t a l foil by 60-fs Laser Irradiation H. Kishimura, H. Morishita, Y.H. Okano, Y. Okano, Y. Hironaka, K.-L Kondo, Y. Oishi, K. Nemoto, K.G. Nakamura

222

E s t i m a t i o n of P r o t o n Source Size G e n e r a t e d by U l t r a i n t e n s e Laser Pulses Using a T h o m s o n Mass S p e c t r o m e t e r Y. Oishi, T. Nayuki, T. Fujii, Y.i Takizawa, X. Wang, T. Sekiya, A.A. Andreev, K. Horioka, T. Yamazaki, K. Nemoto

225

P a r t I I I Ultrafast Dynamics in Solid 1 ( P h o n o n a n d Exciton) Imaging N a n o s t r u c t u r e s with Picosecond Ultrasonic Pulses B.C. Daly, NCR. Holme, T. Buma, C Branciard, T.B. Norris, S. Pau, D.M. Tennant, J.A. Taylor, J.E. Bower

231

XV

U l t r a h i g h Frequency Acoustic P h o n o n Generation a n d Spectroscopy with D e a t h s t a r Pulse Shaping J.D. Beers, M. Yamaguchi, T. Feurer, B.J. Paxton, K. A. Nelson

236

P r o b i n g of Thermo-Acoustic Transients in Materials Using E U V Radiation R.I. Tohey, E.H. Gershgoren, M.E. Siemens, M.M. Murnane, H.C. Kapteyn, T. Feurer, K.A. Nelson

239

Ultrafast Dynamics of Coherent E l e c t r o n - P h o n o n I n t e r a c t i o n in Silicon M. Kitajima, M. Hase, A.M. Constantinescu, H. Petek

242

G e n e r a t i o n of Coherent Zone B o u n d a r y P h o n o n s by Impulsive Excitation of Molecules M. Giihr and N. Schwentner

245

A m p l i t u d e Collapse-Revival of C h i r p e d Coherent P h o n o n s u n d e r High-Density Optical Excitation K. Ishioka, O. V. Misochko, R. Lu, M. Hase, M. Kitajima

248

Intense Coherent Optical P h o n o n s Driven by Impulsive Excitonic Interference u n d e r Electric Fields O. Kojima, K. Mizoguchi, M. Nakayama

251

P h o n o n - P o l a r i t o n Based T H z Spectroscopy B.J. Paxton, M. Yamaguchi, K.A. Nelson

254

Excitonic Q u a n t u m B e a t s Dressed with C o h e r e n t P h o n o n s K. Mizoguchi, T. Furuichi, O. Kojima, M. Nakayama, K. Akahane, N. Yamamoto, N. Ohtani

257

Evidence of Higher-Order Nonlinearities in Excitonic F W M Signals in Microscopic T h e o r y a n d E x p e r i m e n t L. Wischmeier, M. Buck, S. Schumacher, G. Czycholl, F. Jahnke, I. Rilckmann, J. Gutowski

260

Ultrafast Anisotropic Processes of Exciton M a g n e t i c Polarons in C d T e / C d M n T e Q u a n t u m Wires R. Naganuma, T. Kita, S. Nagahara, 0. Wada, L. Marshal, H. Mariette263 Time-Resolved Mid-Infrared Spectroscopy of Excitons in Cu20 M. Kubouchi, R. Shimano, K. Yoshioka, A. Mysyrowicz, M. Kuwata-Gonokami

XVI

266

Exciton Dynamics in P e n t a c e n e a n d Tetracene Studied Using Optical P u m p - P r o b e Spectroscopy V,K. Thorsm0lle, R.D. Averitt, J. Demsar, X. Chi, D.L. Smith, A.P. Ramirez, A.J. Taylor

269

Dephasing Suppression of Excitons in Semiconductors T. Kishimoto, A. Hasegawa, Y. Mitsumori, M. Sasaki, F. Minami . . . . 272 Dynamical Stark Effect of Excitons in C u 2 0 by R e s o n a n t P u l s e d Excitation of t h e l s - 2 p Transition K. Yoshioka, M. Kuhouchi, R. Shimano, M. Kuwata-Gonokami

275

Ultrafast C h a r g e P h o t o g e n e r a t i o n a n d Exciton R e g e n e r a t i o n at Polymeric Semiconductor Heterojunctions A.C. Morteani, P. Sreearunothai, L.M. Herz, R.H. Friend, C. Silva . . . 278 Exciton Diffusion Dynamics in an Organic Semiconductor Nanostructure C. Daniel, L.M. Herz, S. Westenhoff, F. Makereel, D. Beljonne, F.J.M. Hoeben, P. Jonkheijm, A.P.H.J. Schenning, E.W. Meijer, C. Silva

281

P a r t I V Ultrafast Dynamics in Solid 2 Carrier-Envelope P h a s e Controlled Q u a n t u m Interference in a Semiconductor T.M. Fortier, P.A. Roos, D.J. Jones, S.T. Cundiff, R.D.R. Bhat, J.E. Sipe

287

Phase-Resolved Nonlinear Response of M o d u l a t i o n - D o p e d Q u a n t u m Wells u n d e r Femtosecond I n t e r s u b b a n d Excitation T. Shih, C.-W. Luo, K. Reimann, M. Woerner, T. Elsaesser, I. Waldmilller, A. Knorr, R. Hey, K.H. Ploog

292

Ultrafast I n t e r s u b b a n d Relaxation a n d Carrier Cooling in G a N / A l N Multiple Q u a n t u m Wells J. Hamazaki, H. Kunugita, K. Ema, S. Matsui, Y. Ishii, T. Morita, A. Kikuchi, K. Kishino

295

Polaritonics in Complex S t r u c t u r e s : Confinement, B a n d g a p Materials, a n d Coherent Control D.W. Ward, E.R. Statz, J.D. Beers, T. Feurer, J.D. Joannopoulos, R.M. Roth, R.M. Osgood, K.J. Webb, K.A. Nelson

298

XVII

Detection of Four-Wave Mixing Signal from Single Layer Quantum Dots M. Ikezawa, F. Suto, Y. Masumoto, H.-W. Ren

301

Wavepacket Interferometry and Wavepacket Dynamics in Condensed Phase M. Bargheer, M. Fushitani, M. Giihr, N. Schwentner

304

Femtosecond Wavepacket Dynamics of Potassium Adsorbate on P t ( l l l ) K. Watanabe, N. Takagi, Y. Matsumoto

307

Control of Tunnel Ionization in Molecules by Intense Femtosecond Laser Pulses With Time-Dependent Polarization T. Kanai, S. Minemoto, H. Sakai

310

Ultrafast Mid-Infrared Dynamics in the Colossal Magnetoresistance Pyrochlore T12Mn207 R.P. Prasankumar, A.J. Taylor, R.D. Averitt, H. Okamura, H. Imai, Y. Shimakawa, Y. Kubo

313

Femto-Magnetism Visualized in Three Dimensions J.-Y. Bigot, M. Vomir, L.H.F. Andrade, L. Guidoni, E. Beaurepaire, J. Arabski

316

Photo-Induced Demagnetization Observed by TimeResolved Mid-Infared Transmittance Spectroscopy in GaO.94MnO.06As, E. Kojima, J.B.t Heroux, R. Shimano, Y.i Hashimoto, S. Katsumoto, Y. lye, M. Kuwata-Gonokami

319

Optically Induced Magnetization and Ultrafast Spin Dynamics of Magnetic Ions in Ionic Crystals T. Kohmoto, K. Nakazono, S. Furue, M. Kunitomo, Y. Fukuda

322

Dynamic Coupling-Decoupling Crossover in the CurrentDriven Vortex-State in T12Ba2CaCu208 Studied Using Terahertz Time-Domain Spectroscopy V.K. Thorsm0lle, R.D. Averitt, I. Aranson, M.P. Maley, L.N. Bulaevskii, A.J. Taylor

325

Ultrafast Light Induced Charge Disordering Around Phase Transition Temperature in 2D Spin Ladder Compound NaV205 M. Aiba, M. Nakajima, M. Isobe, Y. Ueda, T. Suemoto

328

XVIII

Correlation of t h e Electronic Transitions in Semiconducting Single-Walled C a r b o n N a n o t u b e s Y.-Z. Ma, J. Stenger, S.L. Dexheimer, S.M. Bachilo, R.E. Smalley, R.B. Weisman, G.R. Fleming

331

Ultrafast Radial T r a n s p o r t in a Micron-Scale A l u m i n u m P l a s m a Excited at Relativistic Intensity B.T. Bowes, M.C. Downer, H. Langhoff, M. Wilcox, B. Hou, J. Nees, G, Mourou

334

C h i r p Control of Free Carrier Dynamics in G a A s T. Hattori, T. Yogi, Y. Hama, N. Watanabe

337

Ultrafast Insulator-to-Metal Switching by P h o t o i n d u c e d M o t t Transition S. Iwai, Y. Okimoto, M. Ono, H. Matsuzaki, A. Maeda, H. Kishida, H. Okamoto, Y, Tokura

340

Femtosecond N e a r Edge X-Ray Absorption M e a s u r e m e n t of t h e V 0 2 P h a s e Transition A. Cavalleri, H.H.W. Chong, S. Fourmaux, T.E. Glover, P.A. Heimannn, J.C. Kieffer, H.A. Padmore, R.W. Schoenlein

343

P h a s e Transition in Strongly-Correlated V 0 2 : T i m e - D o m a i n Assignment of Cause a n d Effect A. Cavalleri, T. Dekorsy, H.H. Chong, J.C Kieffer, R.W. Schoenlein . 346 Polarization-Dependent P h e n o m e n o n Induced by t h e Interaction between Focused Femtosecond Laser a n d T r a n s p a r e n t Materials Y. Shimotsuma, J. Qiu, P. G. Kazansky, K. Hirao

349

Investigation on t h e P a r a m e t e r s of Dense Electronic P l a s m a I n d u c e d by Femtosecond Laser in Fused Silica Q. Gong, Q. Sun, Y. Liu, Z. Wu, H. Yang, H. Jiang

354

Dynamical S y m m e t r y Breaking Induced by U l t r a s h o r t Laser Pulses in K T a 0 3 E. Matsubara, J.-I. Takahashi, K. Inoue, E. Hanamura

357

P a r t V Ultrafast Dynamics in Solution Sub-20-fs S t u d y of Energy Relaxation in carotenoids in solution a n d inside light harvesting complexes G. Cerullo, D. Polli, G. Lanzani, H. Hashimoto, R.J. Cogdell

363

XIX

Energy Flow in Carotenoids, Studied With Pump-DepleteProbe, Multiphoton and Coherent Control Spectroscopy T. Buckup, W. Wohlleben, J. Savolainen, B. Heinz, H. Hashimoto, R.J. Cogdell, J.L. Herek, M. Motzkus

368

Amplitude Spectra of Molecular Vibration Modes in Phthalocyanine: Comparison with Raman Excitation Profile T. Kobayashi, M. Hirasawa, Y. Sakazaki, H. Hane

371

Real Time Tracking of the Peaks in Transition Difference Spectra During Vibrational Periods in P D A Y. Yuasa, M. Ikuta, T. Kimura, H. Matsuda, T. Kobayashi

374

Time-Resolved CARS Studies of Vibrational Coherences in the Condensed Phase: 12 in Solid Krypton M. Karavitis, I. Goldschleger, V.A. Apkarian, T. Kumada

377

Measurement of Conical Intersection Dynamics by Impulsive Femtosecond Polarization Spectroscopy D.A. Farrow, W. Qian, E.R. Smith, D.M. Jonas

380

Vibrational Phase Characterization in Femtosecond-Pumped Molecules by Path-Length Modulation T. Taneichi, T. Fuji, Y.u Yuasa, T. Kobayashi

383

Vibrational Energy Relaxation in Water-Acetonitrile Mixtures D. Cringus, S. Yeremenko, M.S. Pshenichnikov, D.A. Wiersma

386

Cascaded Energy Redistribution upon O-H Stretching Excitation in an Intramolecular Hydrogen Bond K. Heyne, M. Petkovic, E.T.J. Nibbering, O. Kilhn, T. Elsaesser

389

Pure Intermolecular Energy Relaxation of the OH Bending Vibration of Water Molecules Dissolved in Organic Liquids G. Seifert, T. Patzlaff, K. Paradowska-Moszkowska, H. Graener

392

Time-Resolved Spectroscopy of an Azobenzene Derivative with a Small S1-S2 Energy Gap M. Hagiri, N. Ichinose, T. Nakayama, C. Zhao, H. Horiuchi, H. Hiratsuka

395

Photo-Thermalization Dynamics of Azulene in Supercritical Fluids Studied by the Transient Grating Method Y. Kimura, Y. Yamamoto, M. Terazima

398

Vibrational Self-Trapping in an a-Helix J. Edler, V. Pouthier, C. Falvo, R. Pfister, P. Hamm

401

XX

Infrared Photon-Echo Spectroscopy of Water: the ThermaHzation Effects M.S. Pshenichnikov, S. Yeremenko, D.A. Wiersma

404

Heterodyne 2D-IR Photon Echo Spectroscopy of Multi-Level OH Stretching Coherences in Hydrogen Bonds N. Huse, B.D. Bruner, M.L. Cowan, J. Dreyer, E.T.J. Nibhering, T. Elsaesser, R.J.D. Miller

407

A Unified Analysis of Ultrafast Vibrational and Orientational Dynamics of H O D in D 2 0 J.J. Loparo, C.J. Fecko, J.D. Eaves, S.T. Roberts, A. Tokmakoff

410

Time Resolved Direct Probing of the Change in the Local Solvent Response Following Excitation of a Solute D.F. Underwood and D.A. Blank

413

Surface Femtochemistry: Photocatalytic Reaction Dynamics of Methanol/Ti02(110) K. Onda, B. Li, H. Petek

416

Three Pulse Four Wave Mixing for the Study of Coherent Interactions, Nuclear Dynamics and Solvation Dynamics in Liquids J.-S. Park and T. Joo

419

Solvation Dynamics of N-Methylacetamide in D 2 0 , CDC13, and DMSO-d6 M.F. DeCamp, L.P. DeFlores, J.M. McCracken, A. Tokmakoff

422

Femtosecond Pump-Probe Measurements of Solvation Dynamics of Hydrogen-Bonding Complexes in NonAssociating Solvents D. Pines, E. Pines, Y.-Z. Ma, G.R. Fleming

425

Novel Time- and Frequency-Resolved Double P u m p Spectroscopy of Short-Lived Precursors: The Solvated Electron in Methanol A. Thaller, R. Laenen, A. Laubereau

428

Ultrafast IR Spectroscopy on Aqueous Reverse-Micellar Nano- D r oplet s D. Cringus, M.T.W. Milder, M.S. Pshenichnikov, D.A. Wiersma, J. Lindner, P. Vohringer

431

Pump-Probe Near-Field Optical Microscopy of Molecular Aggregates Using Supercontinuum T.o Nagahara, K. Imura, H. Okamoto

434

XXI

Vibrational and Rotational Relaxation Dynamics of Anions in Reverse Micelles by Ultrafast Infrared Spectroscopy J.C. Owrutsky, G.M. Sando, Q. Zhong, A.P. Baronavski

437

Part VI Reaction Dynamics in Solution Femtochemistry in the Electronic Groundstate? IR-Driven Cis-Trans Isomerization of HONO P. Hamm, R. Schanz, V. Botan

443

Bimodal Intermolecular Proton Transfer in Acid-Base Neutralization Reactions in Water O.F. Monhammed, M. Rini, J. Dreyer, B.-Z. Magnes, D. Pines, E.T.J. Nihhering, E. Pines

448

Ultrafast Excitation Energy Migration Processes in Various Porphyrin Arrays D. Kim

453

Energy Transfer in Phenylene Ethynylene Dendrimers E. Atas, C.E. Mair, J.S. Melinger, Z. Peng, V.D. Kleiman

456

A 40-fs Time-Resolved Absorption Study of Cis-Stilbene in Solution: Observation of Coherent Nuclear Wavepacket Motion in Reactive Excited State K. Ishii, S. Takeuchi, T. Tahara

459

Monitoring an Ultrafast Photo-Isomerization by Femtosecond Fluorescence, Absorption, and IR Spectroscopy P. Gilch, B. Schmidt, C. Sobotta, M. Braun, F. Roller, T. Schrader, A. Sieg, W. Schreier, W. Zinth

462

From Ultrafast Spectroscopy to Bidirectional Molecular Switches: D H A / V H F U. Schmidhammer, V. De Waele, G. Buntinx, E. Riedle

465

Ultrafast Intramolecular Electron Transfer of 9,9'-Bianthryl as Studied by Femtosecond Time-Resolved Near-Infrared Absorption and Anisotropy in the 950-1500 nm Region T. Takaya, K. Iwata, H. Hamaguchi, H. Kuroda

468

Real-Time Spectroscopy of Charge-Transfer Excitation in Phthalocyanine Tin Dichloride M. Hirasawa, Y. Sakazaki, H. Hane, T. Kobayashi

471

XXII

Coherent Nuclear Dynamics Coupled with Electron Transfer Reaction in Porphyrin-Ferrocence Dyads S. Nakashima, M. Kuho, M. Otani, M. Murakami, Y. Ishibashi, M. Yasuda, H. Miyasaka, Y. Mori, H. Imahori

474

Subpicosecond Pulse Radiolysis Study on Geminate Ion Recombination Process in n-Dodecane Y. Yoshida, A. Saeki, T. Kozawa, J.g Yang, S. Tagawa

479

Fast Spin Dynamics of Optically Induced Magnetization in Aqueous Solutions of Magnetic Ions S. Furue, T. Kohmoto, M. Kunitomo, Y. Fukuda

482

Vibrational Excitation and Energy Redistribution after Ultrafast Intramolecular Proton Transfer of T I N U V I N W. Werncke, V. Kozich, J. Dreyer

485

Coherent Nuclear Motion in Reacting Molecules: Ultrafast Pump-Probe Spectroscopy of Proton Transfer in Solution S. Takeuchi and T. Tahara

488

Ultrafast Double Proton Transfer: Symmetry Breaking Wavepacket Motion and Absence of Deuterium Isotope Effect S. Lochhrunner, K. Stock, C. Schriever, E. Riedle

491

Photodissociation Dynamics Studied via Time-Resolved Coincidence Imaging Spectroscopy O. Gefiner, E, Ter-Heersche Chrysostom, A.M.D. Lee, J.P. Shaffer, C.C. Hayden, A. Stolow

496

Femtosecond Photo-Induced Dissociation of the Trihalide Anions 13- and I2Br- in Solution P. Salen, M. Liu, P. van der Meulen

499

Coherent Control of Non-Radiative Transitions: Long-Range Electron Transfer B.D. Fainherg, V.A, Gorbunov, S.H. Lin

502

Teaching Lasers To Twist Molecules G. Vogt, G. Krampert, P. Niklaus, G. Gerber

505

Quantum Control of a Chiral Molecular Motor Driven by Linearly Polarized Laser Pulses M. Yamaki, K. Hoki, Y. Ohtsuki, H. Kono, Y. Fujimura

508

XXIII

Numerical Synthesis of Optimal Laser Pulses for Manipulating Dissociation Wave Packets of 12- in Water Y. Ohtsuki, Y. Nishiyama, T. Kato, H. Kono, Y. Fujimura

511

Molecular State Reconstruction by Nonlinear Wave Packet Interferometry T.S. Humble and J.A. Cina

514

Femtosecond Coherent Spectroscopic Study of Zn(II) Porphyrin by Chirping-Controlled Ultrashort Pulses M.-C. Yoon, S. Cho, D. Kim

517

Phase Analysis of Vibrational Wavepackets in the Ground and the Excited States in Polydiacetylene M. Ikuta, Y. Yuasa, T. Kimura, H. Matsuda, T. Kobayashi

520

Calculating Ultrafast Nonlinear Optical Signals from Molecules in Cryogenic Matrices M.A. Rohrdanz and J.A. Cina

523

Real-Time Observation of Phase-Controlled Vibrational Wave-Packets in Iodine Molecules Y. Sato, H. Chiba, M. Honda, Y. Hagihara, K. Fujiwara, K. Ohmori, K. Ueda

526

Single-Shot Transient Absorption of 13- in Solutions and Glasses P.R. Poulin and K.A. Nelson

529

Part VII Multiview and Multi-Dimensional Spectroscopy Dynamics of Hydrogen Bonds in Water: Vibrational Echoes and Two-Dimensional Infrared Spectroscopy C.J. Fecko, J.D. Eaves, J.J. Loparo, S.T. Roberts, A. Tokmakoff, P.L. Geissler

535

Dual-Frequency 2D IR Photon Echo of a Hydrogen Bond I. V. Rubtsov, K. Kumar, R.M. Hochstrasser

539

2D-IR Spectroscopy of Transient Species J. Bredenbeck, J. Helbing, P. Hamm

542

Resolving Conformations of Acetylproline-NH2 by Coherent 2D IR Spectroscopy D. Karaiskaj, S. Sul, Y. Jiang, N.-H. Ge

545

XXIV

Ultrafast Vibrational Dynamics of Rotaxanes O.F.A. Larsen, W.J. Buma, D.A. Leigh, S. Woutersen

548

Thermal Denaturing of Proteins: Equilibrium and Transient Studies Using Nonlinear Infrared Probes H.S. Chung, M. Khalil, A.W. Smith, Z. Ganim, A. Tokmakoff

551

Two-Dimensional Optical Heterodyne Spectroscopy of Molecular Complexes I. Stiopkin, T. Brixner, G.R. Fleming

554

Two-Dimensional Measurement of the Solvent Intermolecular Response in Solvation S. Park, J. Kim, N.F. Scherer

557

Two-Dimensional Femtosecond Coherent Anti-Stokes Raman Scattering Spectroscopy Using a Chirped Supercontinuum Generated from a Photonic Crystal Fiber H. Kano and H. Hamaguchi

560

Two-Dimensional Spectroscopy by Spectrally Resolved Real-Time Resonant Coherent Raman Scattering in Polydiacetylene N. Ishii, E. Tokunaga, S. Adachi, T. Kimura, H. Matsuda, T. Kobayashi563 Optical Two-Dimensional Fourier-Transform Spectroscopy of Semiconductor Quantum Wells C.N. Borca, T. Zhang, S.T. Cundiff

566

Degenerate Four-Wave Mixing Spectroscopy Based on Two Dimensional Pulse Shaping T. Hornung, J.C. Vaughan, T. Feurer, K.A. Nelson

569

Propagation and Detection Distortions of Four-Wave Mixing Signals: Application to 2D Spectroscopy A^. Belahas and D.M. Jonas

572

Fourier Transform Measurement of Two-Photon Excitation Spectra: Applications to Microscopy and Quantum Control K.J. Kuharych, J.P. Ogilvie, A. Alexandrou, M. Joffre

575

Part VIII Biology Watching Proteins Function with Picosecond Time-Resolved X-Ray Crystallography P.A. Anfinrud, F. Schotte, M. Wulff

581

XXV

E n e r g y Transfer P a t h w a y s in P h o t o s y s t e m I Studied by One a n d Two Color P h o t o n Echo spectroscopy H.M. Vaswani, J. Stenger, M. Yangz, P. Fromme, G.R. Fleming

586

Dynamics of Carotenoids P r o b e d by Femtosecond Absorption, Fluorescence, and R a m a n Spectroscopy M. Yoshizawa, D. Kosumi, M. Komukai, K. Yanagi, H. Hashimoto. . . . 589 M u l t i - P u l s e Transient Absorption a n d Carotenoid Excited-State Dynamics:/3-Carotene E. Papagiannakis, D.S. Larsen, M. Vengris, I.H.M. van Stokkum, R. van Grondelle

592

Observation and Control of All-Trans-?-Carotene Wavepacket M o t i o n Using P u m p - D e g e n e r a t e Four-Wave Mixing T. Hornung, H. Skenderovic, K.-L. Kompa, M. Motzkus

595

Vibrational a n d Electronic Coherence Observed in Two-Dimensional I n t e g r a t e d T h r e e - P u l s e P h o t o n Echo Y. Nagasawa, M. Ogasawara, Y. Nakagawa, Y. Mori, T. Okada, H. Miyasaka

598

P h o t o n Echo S t u d y of t h e E l e c t r o n - P h o n o n Coupling S t r e n g t h in Molecules and Molecular Aggregates V.I. Prokhorenko, R. van Grondelle, R.J. Dwayne Miller

601

T i m e a n d Frequency Domain Investigations on Ultrafast Photoisomerization Reaction Dynamics of P Y P H. Chosrowjan, S. Taniguchi, N. Malaga, N. Hamada, F. Tokunaga, M. Unno

604

E n t i r e View of Coherent Oscillations in Ultrafast Fluorescence for P h o t o a c t i v e Yellow P r o t e i n R. Nakamura, N. Hamada, H. Ichida, Y. Kanematsu, F. Tokunaga. . . . 607 Ultrafast Excited a n d G r o u n d - S t a t e Isomerization Dynamics of t h e G r e e n Fluorescent P r o t e i n C h r o m o p h o r e in Solution M. Vengris, I.H.M. van Stokkum, X. He, A.F. Bell, P.J. Tonge, R. van Grondelle, D.S. Larsen

610

O p t i m a l Control of Femtosecond Photoisomerization of Retinal in Rhodopsin: Effects of Conical Intersections M. Abe, Y. Ohtsuki, Y. Fujimura, W. Domcke

613

Ultrafast Polarization and Vibrational Motions in Bacteriorhodopsin Studied by Coherent Infrared Emission Spectroscopy

XXVI

H.A. Colonna, G.L Groma, J.-C. Lambry, M. Joffre, J.-L. Martin, M.H. Vos

616

Excited-State Dynamics of the IBu-f-, 3Ag—, and IBu— States in All-Trans-Spirilloxanthin as Revealed by Sub-5-fs Time-Resolved Absorption Spectroscopy T. Kobayashi, K. Nishimura, F.S. Rondonuwu, Y. Koyama

619

Ultrafast Relaxation Inside Proteins: Calculation and Measurement of Electron-Vibration Coupling in Enzymes B.M. Cho, R.a Walker, LP. Mercer, LR. Gould, D.R, Klug

622

Direct Observations of Ligand Rebinding Trajectories in Myoglobin by Femtosecond Mid-IR Spectroscopy S. Kim and M. Lim

625

Coherent Vibrational Climbing in Carboxy-Hemoglobin C. Ventalon, J.M, Eraser, M.H. Vos, A. Alexandrou, J.-L. Martin, M. Joffre

628

Evidence for Non-Separating Four-Point Correlation Functions From IR Pump-Probe Spectroscopy of CO in a Protein Internal Cavity J. Helbing, P. Hamm, K. Nienhaus, G. U. Nienhaus

631

The CO Oscillator as a Probe of Ligand Dissociation Dynamics in Myoglobin J.P. Ogilvie, T. Polack, S. Franzen, M.H. Vos, M. Joffre, J.-L. Martin, A. Alexandrou

634

A 2DIR Study of Backbone Structure and Dynamics of a Dipeptide in Membrane V. Volkov and P. Hamm

637

Engineering Cost Function for Optimizing Coherent Control between Processes with Different Nonlinearities J. Chen, H. Kawano, Y. Nabekawa, H. Mizuno, A. Miyawaki, T. Tanabe, F. Kannari, K. Midorikawa

640

Part IX Ultrafast Nanostructure Photonics and Plasmon Imaging of Localized Silver Plasmon Dynamics with Sub-fs Time and Nano-Meter Spatial Resolution A. Kubo, K. Onda, H. Petek, Z. Sun, Y.S. Jung, H.K. Kim

645

XXVII

Ultrafast Dynamics of Light Transmission t h r o u g h Plasmonic Crystals C. Ropers, R. Miiller, C. Lienau, G. Stibenz, G. Steinmeyer, D.-J. Park, Y.-C. Yoon, D.-S. Kim

650

Ultrafast Near-Field Microscope Imaging of Electron a n d P h o n o n Relaxation in Single Gold Nanoparticle K. Imura, T. Nagahara, H. Okamoto

655

P l a s m o n E n h a n c e d Ultrafast Optical Transmission in Metallic N a n o - A r r a y s A. Dechant and A. Y. Elezzabi

658

Excitation and P r o p a g a t i o n of Surface P l a s m o n Polaritons on Metallic Periodic S t r u c t u r e s G. Torosyan, C. Rau, B. Pradarutti, R. Beigang

661

Ultrafast Dynamics of Periodic Arrays of Holes in a Gold Film V. Halte, A. Benabbas, L. Guidoni, J.-Y. Bigot, A. Degiron, H.J. Lezec, T. W. Ebbesen, P. N. Saeta

664

Surface P l a s m o n Assisted 26 fs, 0.4 keV Electron P u l s e Generation S.E. Irvine and A. Y. Elezzabi

667

Space-Time Control in Ultrafast Nano-Optics T. Brixner, J. Schneider, W. Pfeiffer, F.J. Garcia de Abajo

670

Coherent Control of Ultrafast Linear and Nonlinear Optical P h e n o m e n a in N a n o s t r u c t u r e s M.I. Stockman, D.J. Bergman, T. Kobayashi

673

S P A S E R as Ultrafast Nanoscale P h e n o m e n o n and Device M.I. Stockman and D.J. Bergman

676

Ultrafast Quenching of t h e Ring Closure in Molecular Switches, Self-Assembled on Gold Nanoparticles R. Hania, A. Pugzlys, T. Kudernac, H.T. Jonkman, K. Duppen

679

P a r t X Terahertz Wave and Applications Temporal Spectroscopic Behavior of Terahertz Pulses T r a n s m i t t e d t h r o u g h M e t a l Hole A r r a y s F. Miyamaru and M. Hangyo

XXVIII

685

Surface-Plasraon-Polariton E n h a n c e d Tunneling of T H z R a d i a t i o n t h r o u g h Arrays of Sub-Wavelength A p e r t u r e s J.G. Rivas, C. Janke, P.H. Bolivar, H. Kurz

690

T e r a h e r t z Access t o t h e Nanoworld R. Kersting, H.-T. Chen, N. Karppwicz, G.C. Cho .

693

T e r a h e r t z Surface Plaslmon Polariton Coupling on Metallic Grating Structures J.F. O'Hara, R.D. Averitt, A.J. Taylor

696

Control of T H z Transmission t h r o u g h Two-Dimensional Metallic P h o t o n i c Crystals C.-L. Pan, C.-F. Hsieh, R.-P. Pan, M. Tanaka, F. Miyamaru, M. Tani, M. Hangyo

699

Teflon P h o t o n i c Crystal Fiber as Polarization-Preserving Waveguide in T H z Region M. Goto, A. Quema, H. Takahashi, S. Ono, N. Sarukura

702

G e n e r a t i o n of Coherent Tunable T H z Waves by Using Birefringent Crystal and G r a t i n g P a i r R. Yano, H. Gotoh, T. Hattori

705

U l t r a - W i d e B a n d w i d t h T H z Emission from a Semiconductor I r r a d i a t e d with Intense, Radially Polarized, Bessel-Gauss Pulses K.J. Chau and A. Y. Elezzabi

708

Mechanism Crossover of Terahertz Radiation from I n A s Surface Induced by a Magnetic Field at High Density Excitation M. Nakajima, Y. Oda, S. Saito, T. Suemoto

711

Transient G r a t i n g Generation a n d Waveform Shaping of Free-Space P r o p a g a t i n g , Picosecond, N a r r o w - B a n d T H z Radiation A.G. Stepanov, J. Hebling, J. Kuhl

714

T y p e s e t t i n g T H z Waveforms J.G. Vaughan, T. Feurer, T. Hornung, K.A. Nelson

717

Magnetically Induced Evolution of Terahetz R a d i a t i o n S p e c t r u m E m i t t e d from InAs u p t o 27T H. Takahashi, A. Quema, M. Goto, S. Ono, N. Sarukura, G. Nishijima, K. Watanahe

720

XXIX

A Liquid Crystal P h a s e Shifter with a Tuning R a n g e of Over 360 Degrees a r o u n d 1 T H z O.-Y. Chen, C.-F, Hsieh, R.-P. Chao, C.-L. Pan

723

Cooper Pair Breaking Dynamics in M g B 2 Using OpticalP u m p T e r a h e r t z - P r o b e Spectroscopy J. Demsar, R.D. Averitt, A.J. Taylor, V. V. Kabanov

726

Femtosecond Formation of P h o n o n - P l a s m o n Coupled M o d e s Studied by U l t r a b r o a d b a n d T H z Spectrocopy R. Huher, C. Kiibler, S. Tuhel, A. Brodschelm, F. Kohler, M.-C. Amann, A. Leitenstorfer

729

Solid-State P h a s e Transition Onset Detection in EstrogenLike Chemical via Terahertz Transmission Spectroscopy A.V. Quema, M. Goto, M. Sakai, G. Janairo, R. El Ouenzerfi, H. Takahashi, S. Ono, N. Sarukura

732

M a x i m u m E n t r o p y M e t h o d for Misplacement P h a s e E r r o r Correction in Terahertz Time-Domain Reflection Spectroscopy Y. Ino, R. Shimano, M. Kuwata-Gonokami, E.M. Vartiainen, Y.P. Svirko, K.E. Peiponen

735

P u l s e d T e r a h e r t z Spectroscopy and Imaging Applied t o Inspection of Explosives a n d Inflammable Liquids K. Yamamoto, M. Yamaguchi, F. Miyamaru, M. Tani, M. Hangyo, T. Ikeda, A. Matsushita, K. Koide, M. Tatsuno, Y. Minami

738

T e r a h e r t z T i m e - D o m a i n Spectroscopy of Surface P l a s m o n Polaritons on Semiconductor Surfaces J.G. Rivas, J. Saxler, M. Kuttge, P.H. Bolivar, H. Kurz

741

Evaluation of C o m p l e x Optical C o n s t a n t s of Semiconductor Wafers Using T e r a h e r t z Ellipsometry T. Nagashima and M. Hangyo

744

T e r a h e r t z Two-Dimensional Spectroscopic Imaging w i t h a High Speed C M O S C a m e r a H. Kitahara, T. Yonera, F. Miyamaru, M. Tani, M. Hangyo

747

Single-Shot T e r a h e r t z Imaging R. Rungsawang, A. Mochiduki, S.-I. Okuma, T. Hattori

750

U l t r a b r o a d b a n d Detection of M u l t i - T H z Field Transients w i t h GaSe Electro-Optic Sensors C. Kuhler, R. Huher, S. Tuhel, A. Leitenstorfer

753

XXX

T e t a h e r t z Field Detection beyond 30 T H z by P r o t o n Bombarded InP Photoconductive Antennas T.-A. Liu, M. Tani, M. Nakajima, M. Hangyo, K. Sakai, S.-I. Nakashima, C.-L. Pan

756

T H z Wave Near-Field Emission Microscope T. Yuan, H. Park, J, Xu, H. Han, X.-C. Zhang

759

P a r t XI Optoelectronics and O t h e r Applications Optimization of a 40 G H z Regeneratively a n d Harmonically Mode-Locked F i b e r Laser u n d e r P L L O p e r a t i o n a n d its Longitudinal M o d e Characteristics M. Yoshida, T. Yaguchi, S. Harada, M. Nakazawa

765

Femtosecond Synchronization of RF-Signals w i t h Optical P u l s e Trains J.-W. Kim, M.H, Perrott, F.X. KaeHner

768

Fast P h o t o - I n d u c e d P h a s e Switching in Organic C o n d u c t o r Crystal; ( E D O - T T F ) 2 P F 6 M.C. Chollet, L. Guerin, N. Uchida, S. Fukaya, T. Ishikawa, S.-Y. Koshihara, K. Matsuda, A. Ota, H. Yamochi, G. Saito

771

Molecular P h a s e - t o - A m p l i t u d e Converter Using Femtosecond Wave Packet Engineering /. Matsuda, K. Misawa, N.T. Hashimoto, R. Lang

774

Femtosecond Pulse Recoding and R e g e n e r a t i o n by a T w o - P h o t o n G a t e d Periodic Diffractive Optics H. Nishioka, H. Tomita, K.-L Ueda

777

Linewidth and R I N M e a s u r e m e n t s of Longitudinal M o d e s in Ultrahigh-Speed Mode-Locked Laser Diodes K. Haneda, H. Yokoyama, Y. Ogawa, M. Nakazawa

780

C h a r g e G e n e r a t i o n in I n o r g a n i c / O r g a n i c Photovoltaic Blends 5. Westenhoff, S. C, Hayes, N. C. Greenham, C. Silva

783

E n h a n c e d Polariton Decay in LiNb03 D u e t o Stimulated Emission of Acoustic P h o n o n s J. Hebling, A.G. Stepanov, G. Almdsi, J. Kuhl

786

Ultrafast Electro optic Deflector Using Quasi-VelocityMatching K. Shibuya, S. Hisatake, H. Kitano, T. Kobayashi

789

XXXI

Ultrafast Control of a Surface P l a s m o n Resonance via t h e Insulator t o M e t a l Transition in V 0 2 Nanoparticles M. Rini, A. Cavalleri, R. Lopez, L.A. Boatner, R.F. Haglund Jr., T.E. Haynes, L.C. Feldman, R. W. Schoenlein

792

E x t e r n a l G e n e r a t i o n of Flat Power-Envelope T H z M o d u l a t i o n Sidebands from a C W Laser Based on a n Electrooptic P h a s e Modulator S. Hisatake, Y. Nakase, K. Shihuya, M. Tobinaga, T. Kobayashi

795

P a r t X I I Microfabrication by Femtosecond Laser Pulses 3D P h o t o n i c Devices Fabricated in Glass by a Femtosecond Oscillator A.M. Kowalevicz, V. Sharma, E.P. Ippen, J.G. Fujimoto, K. MinoshimaSOl Writing of P h o t o n i c Devices and Waveguide Lasers by a D i o d e - P u m p e d Femtosecond Oscillator R. Osellame, N. Chiodo, G. Delia Voile, S. Taccheo, R. Ramponi, G. Cerullo, A. Killi, U. Morgner, M. Lederer, D. Kopf

804

Toward t h e Fabrication of H y b r i d P o l y m e r / M e t a l Three-Dimensional M i c r o s t r u c t u r e s T. Baldacchini, C.N. LaFratta, R.A. Farrer, A.C. Pons, J. Pons, M.J. Naughton, B.E.A. Saleh, M.C. Teich, J.T. Fourkas

807

P r o d u c t i o n of 3D, Dichroitic M i c r o s t r u c t u r e s in N a n o c o m p o s i t e Glasses by Femtosecond Laser Pulses G. Seifert, A.V. Podlipensky, A. Abdolvand, J. Lange, H. Graener . . . . 810 M i c r o m e t e r and Sub-Micrometer S t r u c t u r e s Fabrication a n d Analysis w i t h Femtosecond Laser Micro-Nanomachining System E. Vanagas, J. Kawai, Y. Zaparozhchanka, D. Tuzhilin, H. Musasa, P.I Rutkovski, I. Kudryashov, S. Suruga

813

Femtosecond Laser Effects on Osseous Tissues B. Girard, D. Yu, M.R. Armstrong, B.C. Wilson, CM.L. R.J.D. Miller

816

Clokie,

Femtosecond Laser Material Processing: How short is s h o r t ? Y. Prior, K. Zhang, V. Batenkov, Y. Paskover, I.S. Averbukh, F. Korte, C Fallnich

XXXII

819

D i o d e - P u m p e d C r 3 + : L i C A F Laser for Ultrahigh Resolution Optical Coherence Tomography P.C. Wagenhlast, T.H. Ko, V. Sharma, U. Morgner, J.G. Fujimoto, F.X. Kaertner

822

Time-Resolved Electron Imaging of Femtosecond Laser Ablation Y. Okano, Y. Hironaka, K.-L Kondo, K.G. Nakamura

825

P a r t X I I I Frequency Stabilization a n d Ultrawide Frequency C o m b A N e w U l t r a s t a b l e Cesium Optical Atomic Clock w i t h a 9.1926-GHz Regeneratively Mode-Locked Fiber Laser M. Yakabe, K. Nito, M. Yoshida, M. Nakazawa, Y. Koga, K. Hagimoto, T. Ikegami

831

Frequency Transfer of Optical S t a n d a r d s Through a F i b e r Network Using 1550-nm Mode-Locked Sources K. W. Holman, D.J. Jones, R.J. Jones, J. Ye

834

Femtosecond Laser Optical Frequency Synthesizers w i t h U n c e r t a i n t y at t h e 10-19 Level L.-S. Ma, Z. Bi, A. Bartels, L. Robertsson, M. Zucco, R. Windeler, G. Wilpers, C. Gates, L. Hollberg, S.A. Diddams

837

Femtosecond Laser Frequency Combs with Linewidths at t h e 1-Hz Level A.O. Bartels, S.A. Diddams, G.W. Gates, J.G. Bergquist, L. Hollberg . 840 Frequency Metrology w i t h a Turnkey All-Fiber System T.R. Schibli, K. Minoshima, F.-L. Hong, H. Inaba, A. Gnae, H. Matsumoto, I. Hartl, M.E. Fermann

843

Optical Frequency M e a s u r e m e n t Precision of Femtosecond Laser Optical C o m b System and t h e Stability of its H F Reference Frequency H. Ito, Y. Li, M. Fujieda, M. Imae, M. Hosokawa

846

Evaluation of Oscillation Frequency Stability of a Diode Laser Using a fs Laser Optical C o m b H. Kobayashi, T. Nimonji, A. Sawamura, T. Sato, M. Ghkawa, T. Maruyama, T. Yoshino, H. Kunimori, M. Hosokawa, H. Ro, Y. Li, S. Nagano, S. Kawamura

849

XXXIII

P a r t X I V Coherent Control and O t h e r Topics Coherent Cooling of Molecular Vibrational Motion w i t h Laser-Induced Dipole Forces H. Niikura, P.B. Corkum, DM. Villeneuve

855

Molecular Orientation of C H 3 F Induced by Phase-Controlled Lights H. Ohmura, F. Itoh, M. Tachiya

858

Observation a n d Manipulation of Q u a n t u m Interferences in Ladder Climbing B. Chatel, J. DegeH, S. Stock, B. Girard

861

A d a p t i v e Polarization Control of Molecular Dynamics T. Brixner, G. Krampert, T. Pfeifer, R. Selle, G. Gerher, M. Wollenhaupt, O. Graefe, C. Horn, D. Liese, T. Baumert

864

T w o - P h o t o n Absorption Imaging w i t h S h a p e d Femtosecond Laser Pulses W.S. Warren, A. Miller, W. Wagner, T. Ye, M. Fischer, G. Yurtsever 867 Selective T w o - P h o t o n Functional Imaging t h r o u g h Scattering M e d i a Based on Binary P h a s e Shaping I. Pastirk, J.M. Dela Cruz, M. Comstock, V.V. Lozovoy, M. Dantus. . . 870 P h o t o n N u m b e r Squeezing of U l t r a b r o a d b a n d Pulses G e n e r a t e d by M i c r o s t r u c t u r e Fibers H. Furumochi, A. Tada, K. Hirosawa, F. Kannari, M. Takeoka, M. Nakazawa

873

Real-Time, Ultrahigh-Resolution Optical Coherence Tomography a t 1.5 |im using a Femtosecond F i b e r Laser Continuum A^. Nishizawa, Y. Chen, P.-L. Hsiung, V. Sharma, T.H, Ko, E.P. Ippen, J. G. Fujimoto

876

Ultrafast Exciton T r a n s p o r t in Organic N a n o t u b e s A. Pugzlys, P.R. Hania, C. Didraga, V.A. Malyshev, J. Knoester, K. Duppen

879

Ultrafast Molecule t o Semiconductor Electron Transfer via Different Anchor G r o u p s in Ultra-High V a c u u m R. Ernstorfer, L. Gundlach, S. Felber, R. Eichberger, C Zimmermann, W. Storck, F. Willig

882

XXXIV

Controllability in Dissociative Ionization of Organic Molecules with Pulse-Shaped Intense Laser Fields H. Yazawa, T. Okamoto, T. Yamanaka, F. Kannari, R. Itakura, K. Yamanouchi

885

Laser Coulomb Explosion Imaging for Probing Molecular Structure and Dynamics F. Legare, K.F. Lee, I.V. Litvinyuk, P.W. Dooley, A.D. Bandrauk, D.M, Villeneuve, P.B. Corkum

888

Ultrafast Electron Transfer via a Bridge-Extended Donor Orbital R. Ernstorfer, L. Gundlach, S. Felber, W. Storck, R. Eichherger, C. Zimmermann, F. Willig

891

Multiple Ionization of Atoms by 25 and 7 fs Laser Pulses A. Rudenko, B. Feuerstein, K. Zrost, V.L.B. de Jesus, CD. Schroter, R. Moshammer, J. Ullrich

894

Time Resolved, Phase-Matched Harmonic Generation from Exploding Noble Gas Clusters B. Shim, G. Hays, M. Fomyts^kyi, A. Arefiev, B.s Breizman, T. Ditmire, M. C. Downer

897

Index of Contributors

901

XXXV

Part I

Generation and Measurements

Single-Cycle Optical Pulse Generation David R, Walker, Miroslav Shverdin, Deniz Yavuz, Guang-Yu Yin, and Stephen E. Harris Edward L. Ginzton Laboratory, Stanford University, Stanford, CA 94305, USA

Abstract. By electronically adjusting the phases of seven Raman sidebands which span 1.56 fim to 410 nm we generate a train of well-formed single-cycle optical pulses with a pulsewidth of 1.6 fs. We have recently attained a milestone result: the generation of a train of single-cycle optical pulses with a pulsewidth of 1.6 fs, a pulse spacing of 11 fs, and a peak power of f=5^: 1 MW. The paper describes the generation of these pulses and the first use of a single-cycle pulse for four-wave mixing to the ultraviolet. We use Raman generation at maximum coherence to produce a wide coUinear spectrum spanning 1.9 octaves from 1.56 /xm to 410 nm [1-3]. This generated spectrum is passed through a Uquid crystal spatial Hght modulator where the phases of seven sidebands are independently set to compensate for the dispersion of the following glass window and optics to form a mode-locked train of single-cycle pulses inside a cell of xenon. The synthesized temporal waveform is characterized by using nonresonant four-wave frequency mixing to the ultraviolet as a nonlinear detector. The Raman sidebands mix in xenon to produce six generated ultraviolet frequencies. By changing the relative phases of the incident Raman sidebands with the liquid crystal array, we coherently control the dipole moment of the medium and are able to change the ratio of the intensities of the generated ultraviolet wavelengths. By choosing phases that maximize the four-wave mixing signal at all ultraviolet frequencies, we form the shortest pulse that this spectrum may make* The pulsewidth and shape are determined by electronically synthesizing two pulses which are then cross-correlated. The experimental set-up is shown in Fig. 1. The Raman sidebands are produced by driving the x/" = 0, J'' = 0 —> i/' = 1, J ' = 0 vibrational transition of deuterium (D2) by two transform-limited laser pulses at 1064 nm and 807 nm, such that their frequency difference is slightly detuned from 2994 cm~"^, the (D2) transition frequency. The first laser is a Spectra Physics Quanta Ray GCR-290 Q-switched injection-seeded Nd:YAG, producing 70 mJ, 10 ns pulses at a 10 Hz repetition rate. The second laser is a homemade ringcavity Ti:Sapphire system pumped by the second harmonic of a separate Nd:YAG Spectra Physics Quanta Ray laser. This laser is injection-seeded by a diode laser and produces transform-limited 60 mJ, 15 ns pulses at the

Liquid crystal phase modulator \ ] ^

PMT

Y

^

1+ ^ 1

Xel

4 i4

D2cell

Xe cell Fig, 1. Experimental set-up for pulse generation and characterization. The Raman sidebands are laterally separated with a prism pair, allowing independent control of each sideband. After being recombined with another prism pair, the sidebands are focused into a Xe cell. Four-wave mixing serves as a phase-sensitive nonlinear detector. A soiar-bHnd photomultiplier tube measures the new frequencies produced in the xenon cell. seeding wavelength at 10 Hz. The seeding wavelength of the diode laser is tunable and monitored by a wavemeter. The two laser beams are combined and loosely focused into an 80 cm D2 cell, where the 1064 nm and §07 nm beams focus to spot sizes of 1.1 nam and 600 ^m, respectively. At the focus, the intensity of each laser is about 1 GW/cm^, and the Raman transition is driven about 700 MHz below resonance, allowing us to adiabatically prepare a uaolecular coherence with peak magnitude \pge[ ^ 0 . 1 . The deuterium cell is cooled with liquid N2 aud kept at a pressure of 60 torr and a temperature of 77 K. The cooling decreases the Doppler linewidth and increases the gi'ound state population, dramatically improving the generation efficiency. At the output of the D2 cell, we observe coUinear generation of 15 discrete vSidebands separated by 2994 cm""^ and extending from 1.56 jum to 207 nm. The generated beams are expanded and coUirnated by a pair of fused silica lenses. The beams pass through two interference filters which selectively attenuate the 1064 nm and 807 nm pump beams in order to avoid damaging the liquid crystal spatial light modulator (LCM). Next, the spectrum is dispersed with a pair of fused silica prisms and all sidebands with a wavelength shorter than 410 nm are blocked. The prisms are adjusted to make the dispersed beams parallel as they pass through the LCM. The LCM is a linear array of 640 pixels, each 97 /xm wide and separated by 3 /xm. The refractive index of each pixel is controlled by an applied voltage. This enables us to independently adjust the phase of each sideband. By using the full spectral range of the LCM, we have obtained phase control over seven of our Raman sidebands. After phase adjustment, these sidebands are spatially recombined with another prism pair and focused with an achromatic lens of focal length

20 cnij into an 8 cm long cell, containing xenon (Xe) vapor at a pressure of 100 torr. The four-wave mixing inside the Xe cell is used to characterize the generated pulses. The efftciency of conversion to the ultraviolet ranges, depending on the spectral component, from lO"*^^ to 10^^, These sidebands are detected by a solar-blind photomultiplier.

•

•

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cross-correlation data

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Fig. 2. Correlation studies of the Raman spectrum. Shown is the four-wave mixing signal at 329 nm {top figure) and at 365 nm (bottom figure) versus the time delay between two phase-optimized pulses. The pulse consisting of the 1064 nm, 650 nm, and 468 nm sidebands is electronically delayed with respect to a pulse synthesized from the 1560 nm, 807 nm, 544 nm, and 410 nm sidebands. The resulting crosscorrelation data is represented by the solid circles. The dashed line represents the corresponding theoretically obtained cross-correlation. We achieve phase-locking inside the xenon cell by adjusting the phases of the sidebands to maximize generation at one of the ultraviolet frequencies. We

then perform a cross-correlation asfollows:We add to each even sideband a phase proportional to itsfrequencyand leave the phases of the odd sidebands unchanged. This effectively forms two pulses which have a v^lable time delay. By varying this delay, we obtain the cross-correlations of Fig. 2. The basis for the calculation is a formalism for optical frequency conversion with gaussian beams with different confocal parameters [4]. The formalism is modified to include the interference of all four-wave mixing contributions to the dipole moment at each generated ultraviolet frequency. Experiment (solid circles) and theory (dashed lines) are matched at their peak values for each of the two generated wavelengths which are shown. The agreement at all time delays is excellent. Repeated experimental tests have shown that changing the phase of any sideband by a fraction of a radian is sufficient to distort the subsequent correlation trace. Fig* 3 shows the calculated instantaneous electric field as obtained with the measured experimental intensities

-1$

-10

-5

0 time (fs)

5

2

0 time (fs)

2

Pig* 3. Theoretically calculated intensity waveform, showing the pulse train (left) and a single pulse (right). By adjusting the phases of the Raman sidebands, it is possible to produce an envelope with a full width at half maximum of L6 fs. and mode-locked phases. The excellent agreement of theory and experiment in Fig. 2, together with the sensitivity to deliberate phase distortion, substantiates our conclusion that we have obtained single-cycle pulses with a width of 1.6 fs. This work was supported by the U. S. Air Force Office of Scientific Research, the U. S. Army Research Office, and the U. S, Office of Naval Research, and the Fannie and John Hertz Foundation.

References 1. S, E. Harris and A. V. Sokolov: Phys. Rev. Lett. 81, 2894 (1998); A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris: Phys. Rev. Lett. 85, 562 (2000). 2. J, Q. Liang, M. Katsuragawa, F. Le Kien, and K. Hakuta: Phys. Rev. Lett. 85, 2474 (2000); M. Katsuragawa, J. Q. Liang, F. Le Kien, and K. Hakuta: Phys. Rev. A 65, 025801 (2002). 3. A. V. Sokolov, D. R. Walker, D. D. Yavuz, G. Y. Yin, and S. E. Harris: Phys. Rev. Lett. $7, 033402 (2001); D. D. Yavuz, D. R. Walker, M. Y. Shverdin, G. Y. Yin and S. E. Harris, Phys. Rev. Lett. 91, 233602 (2003). 4. G. Hilber, D. J. Brink, A. Lago and R. Wallenstein: Phys. Rev. A 38, 6231-6239 (1988).

Toward a terawatt few-optical-cycle driver laser for attosecond spectroscopy N. Ishii^'^ R. Butkus^ A. Baltuska^'^ E. Goulielmakis^'^ M. Uiberacker^'^ R. Kienberger^'^ T. Fuji\ V. S. Yakovlev\ V. Smilgevicius^ R. Danielius^ A. Piskarskas^, and F. Krausz^'^ ^ Institut fUr Photonik, TechnischeUniversitat Wien, Gusshausstrasse 27/387, A-1040 Vienna, Austria E-mail: [email protected] ^ Max-Planck-Institut fur Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany ^ Laser Research Center, Vilnius University, Sauletekio ave. 10, LT-2040 Vilnius, Lithuania Abstract. We discuss routes towards developing an ultra-high peak power phase-stable source of few-cycle laser pulses suitable for driving a wide range of strong-field applications. Experiments with a phase-stable 0.1-TW 5-fs system based on a Ti:sapphire amplifier and the progress in construction of a 1-TW few-cycle optical parametric amplifier are presented. Generation of isolated attosecnd coherent pulses of XUV and soft-X-ray radiation [1-3] is opening, for the first time, an opportunity to perform a direct time- and frequency-domain investigation of atomic and molecular processes that are comparable in their duration to the electron orbiting time. A well-understood and currently favored method for producing such attosecond bursts is the higherorder harmonic generation in gases. This approach relies on a three-step interaction of an atom of gas with an intense driver laser field leading to ionization, electron acceleration by the electric field of the same light pulse, and electron recombination with the parent ion, upon which a high-energy quantum might be emitted [4]. To enable spectroscopy with isolated attosecond pulses, a dedicated driver laser has to be constructed according to a set of specific demands that determine the pulse duration, its intensity, and the position of optical field oscillations under the pulse envelope (referred to, for simplicity, as the carrierenvelope phase, or CEP). These demands can be summarized as follows: 1) the light-matter interaction leading to a non-recursive emission of a XUV-X-ray pulse has to be confined to a single (acting) optical cycle; 2) pre-ionization of the target gas by the optical cycles preceding this interaction should be low; 3) the peak intensity of the acting light cycle should be high; 4) the CEP should be controlled and stabilized; 5) the pulse-to-pulse amplitude fluctuations have to be minimized. Some applications may impose additional requirements, such as control over the time-dependent state of light polarization and a very high pulse contrast with respect to pre-pulses. Essentially, a laser delivering intense quasi-monocycle

CEP-controlled pulses is well suited for the role of an attosecond laboratory workhorse. Recently, we have succeeded in constructing such a laser system by merging the technology of a 5-fs amplifier with the CEP-stabilized Tiisapphire seed oscillator [5]. In this system, the slow CEP drift attributed to the multi-pass Ti:sapphire amplifier is monitored at the amplifier output and is pre-compensated in the CEP control loop of the seed oscillator. In this system, reproducible isolated attosecond pulses can be attained with this laser setup and maintained stable over a period up to several hours. Our setup for generation of isolated attosecond pulses driven by a phase controlled laser system is presented schematically in Fig.l. Ptimplas^r

AOM

Ti:Saosciliator

\^i.iZi"/!:S::.f9
^ 2

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Fig. 2. (a) Spectral intensity and phase of the compressed pulse and (b) corresponding reconstructed temporal profile.

4.

Conclusions

We have developed a sub-10 fs multi-mJ laser system with a pressure-gradient hollow fiber. Further shortening of the pulsewidth is possible by increasing the input energy to the fiber and by optimizing the dispersion induced by the chirped mirrors. This straightforward pulse compression technique can be applied to terawatt-class CPA systems which will open a way to the study of ultrafast x-ray nonlinear optics. Acknowledgements. One of the authors (Oishi) was supported by the Junior Research Associate Program of RIKEN.

References 1 S. Sartania, Z. Cheng, M. Lenzner, G. Tempea, C. Spielmann, and F. Krausz, Opt. Lett.22,1562,1997. 2 A. Suda, M. Hatayama, K. Nagasaka, and K. Midorikawa, in Tech. Digest of CLEO2003, (OSA, Washington D.C., 2003) CThPDAl. 3 G. Cheriaux, P. Rousseau, F. Salin, J. P. Chambaret, B. Walker, and L. F. Dimauro, Opt. Lett. 21,414,1996. 4 S. Backus, J. Peatross, C. P. Huang, M. M. Murnane, and H. C. Kapteyn, Opt. Lett. 20,2000, 1995. 5 L. Gallmann, D. H. Sutter, N. Matuschek, G. Steinmeyer, U. Keller, C. laconis, and I. A Walmsley, Opt. Lett. 24, 1314, 1999.

30

Generation of 14-fs ultrashort pulse in all fiber scheme by use of highly nonlinear hybrid fiber Takashi Hori^ Norihiko Nishizawa\ and Toshio Goto^ ^ Department of Quantum Engineering, Nagoya University, Nagoya 464-8603, Japan E-mail: [email protected] Abstract. We present the all fiber pulse compression using the highly nonlinear hybrid fiber. The 100-fs pulse from the fiber laser is compressed into 14-fs pulse at the center wavelength of 1560 nm.

1.

Introduction

The generation of the ultrashort optical pulse provides a lot of applications such as the ultrafast spectroscopy, supercontinuum generation, optical sampling, and pump-probing analysis. The realization of all-fiber system in the femtosecond pulse generation is desirable in terms of stability, compactness, and practicality. So far, the generation of the 20-fs-class pulse by the higher-order soliton compression in the optical fibers have been reported [1,2]. Here, w^e present the all fiber sub20-fs pulse generation using the optimally designed highly nonlinear hybrid fiber.

2.

Experiment and results

(a)

Er-doped femtosecond fiber laser

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D

1400

1600

1800

2000

Wavelength (nm)

Fig. 1. (a) Experimental setup for the all fiber pulse compression and (b) dispersion curves of the fibers and BK7 glass used in the pulse compressor. Figure 1 shows the experimental setup. The light source is a passively modelocked erbium-doped fiber laser. It generates -100 fs sech^-like pulses at a repetition frequency of 48 MHz, the center wavelength being 1560 nm. The pulse compressor is constructed from the different kinds of fibers using the flision splicer. Figure 1 (b) shows the dispersion curves of these fibers. We determined the optimal length of each fiber from the results of the numerical calculation and the actual experiment. The compressed pulse is evaluated by the second-harmonic generation frequency-resolved optical gating (SHG-FROG) [3]. In the numerical 31

calculation, the generalized nonlinear Schrodinger equation is solved by using the split-step Fourier method [4], We considered the higher-order nonlinear effects, such as the self-steepening and stimulated Raman scattering and used the nonlinear response function of the fiber that both the electronic and vibrational Raman contributions were included. For the dispersion effects, we considered the terms up to the 6th order dispersion parameters of the fibers. ^950 S9OO (a) ^850 _! 800 ? 750

.(b)

. (c)

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(b 650 CO 600 -200

-100

0

100

200

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100

200

-100

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100

200

Time (fs)

Fig. 2. Experimentally measured SHG-FROG traces at the output of the (a) fiber laser, (b) PMF, and (c) BK7 lens. Figure 2 shows the measured SHG-FROG traces at each point in the pulse compressor. The number of data points of the spectrograms used in the retrieval procedure are 256x256. The retrieved and numerically calculated temporal waveforms are shown in Fig 3. The retrieved error was less than 1%. The pulse from the fiber laser is firstly compressed by utilizing the effect of the higher-order soliton compression in the polarization maintaining fiber TPMF). The mode-field diameter and nonlinear coefficient are 5.84 jim and 4.8 W km"^ at the wavelength of 1.55 |im, respectively. As increasing the propagation length, the temporal width is compressed gradually until the optimal length. When the peak power of the pulse injected into the fiber was 3.7 kW (correspondmg to N-2 soltion), the 34-fs pulse was observed. (Fig. 3 (a)) Next the pulse is injected into the highly nonlinear dispersion shifted fiber (HNL-DSF) and its spectrum is broadened by the self-phase modulation (SPM). The ZDW of this fiber is 1545 nm and it is almost matched with the laser wavelength. The nonlinearity of this fiber is enhanced by doping the germanium into the silica core and by the small effective core area [5]. The mode-field diameter of the HNL-DSF is 3.7 |im and the nonlinear coefficient is as large as 21 W"^km"\ As increasing the fiber length of the HNL-DSF, the further spectral broadening occurs and the wideband supercontinuum is generated [6]. In the temporal domain, however, the oscillation structure appears on the waveform and the pulse break-up occurs due to the effect of the group delay dispersion (GVD) of the fiber [7]. The fiber length of the HNL-DSF is determined as the distortion of the temporal waveform can be ignored. In the final stage, the pulse is further compressed by compensating the chirp induced in the HNL-DSF. We used the BK7 collimator lens (^=2 mm) as the compressor. The positive chirp induced in the HNL-DSF is compensated by the negative chirp of this lens. According to the numerical calculation, the conventional single mode fiber (SMF) can be used in place of the lens. Finally, the

32

14-fs pulse was experimentally obtained. (Fig. 3 (b)) The output average power was 25 mW and the estimated peak power was -18 kW. Experiment

Numerical calculation

10

10

(a) 5

5 0

:---

.__^''

/\34fsFWHM 1 \

/ \

>> c

03 JO.

1

•(b)

)

-5 CD

10 i"

, w

c 0) c

/V\

*-/fi f

/

\ \ ^ \

^V

5 1.4 c 1.2

Time [ps]

3 CtJ

>* c

500

550

600

650

700

750

(nm)

250

275

300

325

350

375

(nm)

• ! ZAP-SPIDER

Fig. 2. (a) Experimental setup: X/2, achromatic half-wave plate; P1-P2, fused silica prisms; GAP, off-axis parabolic mirrors; BBO, frequency doubling crystal; P3-P5, calcium fluoride prisms; DM, deformable mirror, (b) NOPA spectrum and (c) ultraviolet spectrum generated by achromatic frequency doubling.

80

through a 4-f setup with a deformable mirror (DM) in the Fourier plane to adjust the higher order chirp [1]. The final UV beam propagates without noticeable angular dispersion or change in diameter over a distance of several meters. No lateral variation of the spectrum is found experimentally.

3. Characterization and pulse compression The presented scheme forms a prism compressor with a conversion of the visible spectral components to the UV in the middle. The overall compression can be varied without changing the achromatic behavior by scaling the prism separation together with the focal length of the off axis parabolic mirrors. The setup is designed to compensate for the initial chirp of the NOPA pulses and therefore the pulses are still slightly chirped at the point of second harmonic generation. This is advantageous to prevent sum frequency generation between separate parts of the spectrum. We fully characterize the temporal structure of the UV pulses with the zeroadditional-phase variant of SPIDER (ZAP-SPIDER) [8]. For the demonstration of tunable UV pulses the spectral width of the UV was restricted to a Fourier limit of about 8 to 10 fs by narrowing the NOPA spectrum. Highly stable (~ 3 % rms) UV pulses are generated in a wide tuning range from 275 to 335 nm (see Fig. 3a). Figure 3b) shows a spectrum around 290 nm with a Fourier limit of 6.4 fs and the corresponding pulse shape after adaptive compression with the deformable mirror (Fig. 3c)). The measured pulse duration of 7.1 fs is within 15% of the Fourier limit. To our knowledge these are the (^) -1/1 «rv^ 15 nm ._ «. 14 nm ^ ^ 17 nm 21 nm shortest tunable UV pulses re9.8 fs, ported so far.

260 - I — » - —I—"—1—»—r-i

r(b) 6.4 fs M -• • \^^J 1 1 1 „ L _ J 1 1260 280 300 (nm)

7.1 fs

-40-20 0

Fig. 3. (a) Spectra of tunable ultraviolet pulses with their widths and Fourier limits, (b) Spectrum and (c) temporal shape of a 7.1 fs pulse at 290 nm.

20 40 (fs)

References 1 2 3 4 5

p. Baum, S. Lochbrunner, and E. Riedle, Opt. Lett. 29, 1686 (2004). V. D. Volosov and E. V. Goryachkina, Sov. J. Quantum Electron. 6, 854 (1976). T. R. Zhang, H. R. Choo, and M. C. Downer, Appl. Opt. 29, 3927 (1990). T. Kanai, X. Zhou, T. Sekikawa, and S. Watanabe, Opt. Lett. 28, 1484 (2003). B. A. Richman, S. E. Bisson, R. Trebino, E. Sidick, and A. Jacobson, Opt. Lett. 23, 497 (1998). 6 R. A. Cheville, M. T. Reiten, and N. J. Halas, Opt. Lett. 17, 1343 (1992). 7 P. Baum, S. Lochbrunner, L. Gallmann, G. Steinmeyer, U. Keller, and E. Riedle, Appl. Phys. B 74 [Suppl.], S219 (2002). 8 P. Baum, S. Lochbrunner, and E. Riedle, Opt. Lett. 29, 210 (2004).

81

Ultrabroad-band noncollinear optical parametric amplification in some new nonlinear optical crystals Pathik Kumbhakar^'^, and Takayoshi Kobayashi^ ^ Department of Physics, Graduate School of Sciences, University of Tokyo, 7-3-1 Kongo, Bunkyo-ku, Tokyo 113-0033, Japan E-mail: [email protected] ^ Present address: Department of Physics, National Listitute of Technology-Durgapur (Deemed University), Durgapur-713209, India E-mail: [email protected] Abstract. Some new^ nonlinear optical crystals have been found to be suitable for generation of tunable visible ultrafast laser radiation by type-I noncollinear OPA. Moreover, the condition for ultrabroad-band parametric amplification has been derived straightforwardly.

1.

Introduction

Recently, generation of a-few optical cycle ultrashort visible and near-infrared optical pulses has become a routine technique by type-I noncollinear OPA (NOPA) in BBO crystal [1-3]. Growths of several new nonlinear optical (NLO) borate-group crystals, such as CLBO (CsLiBgOio), KABO (K2AI2B2O7), and LB4 (Li2B407) have also been reported recently. We have demonstrated for the first time the potentialities of these crystals for the generation of visible-near-infrared ultrashort laser radiation by type-I NOPA pumped by 395nm radiation [4,5]. The numerically estimated parametric bandwidths of type-I NOPA in CLBO, KABO, LB4, and BBO crystals are - 200, 184, 217, and 190 nm, respectively, for 1mm thick crystal, with the pump-seed noncollinear angle a= 3.0°, 3.4°, 2.9°, and 3.7°, respectively. A simple and straightforward method is also presented for the derivation of the condition of GV matching between the signal and the idler radiations of type-I NOPA [5].

2.

Condition for group-velocity matching and parametric bandwidths of type-I NOPA in BBO, CLBO, KABO, and LB4 crystals

A straightforward derivation of the condition required for achieving broad-band signal wavelength insensitive phase-matching in a type-I NOPA in a negative uniaxial crystal is presented below.

82

By solving the conditions of type-I noncollinear phase-matching in a negative uniaxial crystal, the following expression of 0 can be obtained. 6 = cos'

^[{(v/r^^)'-i}/{(v/r)'-i}

(1)

Where V = 27rWp7>^, V = ^nn^"'^. K = 2nn,VX,, k^ = Inn^lX,, ^"^^V[(OM^O^+2^sVcosi//], y/=a + p, p=sm\{Klkt)smal and a C ^ i s the noncollinear angle between the pump and signal (idler). The superscript (o/e) corresponds to the polarization. Now, in case of monochromatic pump ^in Eq. (1) will not be dependent (to the first order) on the frequency of die signal {co^ of NOP A, if dO/dco^ = 0. After some algebraic simplifications the condition becomes (cosi///vs - l/vi)/cos>^= 0, [5]. This is equivalent to. (2)

Vs = Vi cos (//,

where Vs and Vi are the group velocities of signal and idler, respectively. Equation (2) is called as the condition for GV matching between signal and idler of NOPA [2]. It is important for us to mention here that by taking the first derivative of the wave-vector mismatch {Ak) with respect to the signal frequency the above condition, Eq. (2) had been derived by others [2,6]. 1.0 1

^xxr

/ 0.8 1 i-i^ 11 V'r' ^ •

^

0.6H

\ r/

LB4 BBO - • • CLBO KABO

0.4 J I;/'

o

1 \'\ /;/ /;/'

0.2 11

\\ -A

"Lf*/

0.0 1

500

600

1•

1

700

'

—

1

800

Signal wavelength (nm) Fig. 1. Acceptable power spectrum of the type-I NOPA in LB4, BBO, CLBO, and KABO crystals with a =1.9°, 3.7°, 3.0°, and 3.4°, respectively.

For broadband amplification in LB4, CLBO, and KABO crystals, the optimum values of the pump-seed noncollinear angle (^opt) are 2.9°, 3.0°, and 3.4°, respectively [4,5]. The parametric gain of NOPA is proportional to sinc^ {LkLIT), the acceptable power spectrum [6], where M=k^(6)-k^zid%a-kiZQ^p, is the wavevector mismatch parallel to the pump (^^^), and L is the optical interaction length in the crystal. From Fig. 1 it is observed that the parametric bandwidths (FWHM) of NOPA in the considered noncollinear configuration in 1-mm thick BBO,

83

KABO, CLBO, and LB4 crystals are ~ 190, 184, 200, and 217 nm, respectively. The gain bandwidth of NOPA being inversely proportional to the effective inverse GV mismatch (GVMs.j) [2], the smaller value of GVMs.i is desirable. The calculation resuhs show that the maximum value of \GVMs.i\ is lower for CLBO and LB4 crystals than those of others in the wavelength region of consideration. 4.

Conclusions

We have found that in newly developed KABO, CLBO and LB4 crystals generation of few-cycle visible (around 630nm) laser radiation is possible by Ti:sapphire second harmonic (395nm) pumped type-I NOPA [4,5]. The numerically estimated bandwidth (~ 217nm) of type-I NOPA in 1-mm LB4 crystal is the widest. However, considering that the parametric gain (G) of the NOPA is proportional to cf^^ /p Z^, the damage threshold intensity of LB4 is - 3 times higher than that of BBO and d^a is ~ 1/10-th that of BBO; with the highest pump intensity (/p) the maximum value of G of an LB4 NOPA should be - 3/10^ times smaller than that of BBO, if the crystal thickness (Z) is the same. Taking a thicker crystal, say, 4.5-mm it may be possible to compensate the low parametric gain, however with reduced amplification bandwidth of-134 nm with L= 4.5-mm and a = 2.95°. The present results may bring interest to the researchers in this field to develop ultrafast laser radiation source using some of these new crystals having advantageous properties, in particular for easy growth and for handling in practical experiments. Acknowledgements. We are grateful to the Ministry of Education, Science and Culture, Government of Japan for the financial support (Grant No. 14002003).

References 1.

2.

3. 4.

5.

6.

84

F. Hache, M. Cavallari, and G. M. Gale, "Ultrafast visible optical parametric oscillators: a route to tunable sub-10-femtosecond pulse," Ultrafast Phenomena X, P. F. Barbara, J. G. Fujimoto, W. H. Knox, and W. Zinth, eds., Vol. 62 of Springer series in Chemical Physics (Berlin, Heidelberg, 1996), pp. 33. A. Shirakawa and T. Kobayashi, "Noncollinear phase- and group-velocity matching of optical parametric amplifier for ultrashort pulse generation," lEICE Trans. Electron. E81-C, 246-253 (1998). G. Cerullo and S. De Silvestri, "Ultrafast optical parametric amplifiers," Rev. Sci. Instrum. 74, 1-18 (2003). A. Baltuska and T. Kobayashi, "Adapting shaping of two-cycle visible pulses using a flexible mirror," Appl. Phys. B. Lasers Opt. B 75, 427- 443 (2002). P. Kumbhakar and T. Kobayashi, "Ultrabroad-band phase matching in two recently grown nonlinear optical crystals for the generation of tunable ultrafast laser radiation by type-I noncollinear optical parametric amplification," J. Appl. Phys. 94, 1329-1338 (2003). P. Kumbhakar and T. Kobayashi, "Nonlinear optical properties of Li2B407 (LB4) crystal for the generation of tunable ultra-fast laser radiation by optical parametric amplification," Appl. Phys. B. Lasers Opt. B 78, 165-170 (2004). Y. Nabekawa and K. Midorikawa, "Broadband sum frequency mixing using noncollinear angularly dispersed geometry for indirect phase control of sub-20-femtosecond UV pulses," Opt. Exp. 11, 324-338 (2003).

Design of Multilayer Mirrors for the Reflection of Sub-Femtosecond Pulses in the XUV Spectral Region Alexander S. Pirozhkov^ Hiroyuki Daido^ Sergei V. Bulanov^ Eugene N. Ragozin^ ^ Advanced Photon Research Center, Japan Atomic Energy Research Institute, 8-1 Umemidai, Kizu-cho, Soraku-gun, Kyoto 619-0215, Japan. E-mail: [email protected] ^ Division of Optics, P. N. Lebedev Physical histitute of the Russian Academy of Sciences, 53 Leninsky prospekt, 119991 Moscow, Russia Abstract. Theoretically demonstrated that aperiodic multilayer mirrors can compress negatively and positively chirped XUV pulses. In particular, temporal profiles of reflected trains of positively chirped high-order harmonics of a laser radiation were calculated.

Introduction. The recent progress in the generation and characterization of subfemtosecond pulses in the XUV spectral region [1,2] calls for the development of suitable optical elements. Among the most efficient XUV optical elements are multilayer mirrors. Up to now, only periodic multilayer mirrors were used for the reflection of sub-fs pulses. The shortest pulse generated in [1] had the duration of 0.25 fs which was almost limited by the bandwidth of the multilayer used (9 eV). This means that further decrease in the pulse duration is impossible without a broadband aperiodic multilayer mirrors. The first broadband aperiodic XUV multilayer mirrors for the 12.5-25 nm spectral range were successfully synthesized and used as focusing elements of the imaging XUV spectrograph in [3,4]. Evidently, for the reflection of ultrashort pulses an increased attention should be paid to dispersive (or phase) properties of multilayer structures. We extended the method of calculation of aperiodic multilayer mirrors for the reflection of ultrashort pulses and designed mirrors for the compression of chirped pulses and the simultaneous reflection of several high-order harmonics. Calculation of temporal profiles of reflected pulses. The inverse problem of XUV multilayer optics - that is, the problem of calculation of an aperiodic multilayer structure that gives an extremum of a prescribed merit function - was first stated in [5]. Later this problem was solved with different methods by many authors (e.g. [6-10]). We used a specially designed genetic algorithm for the optimization of aperiodic multilayer structures. Optimization parameters were thicknesses of all layers. In contrast to previous papers, the merit function was taken in the form ofl^r, where /max is the peak intensity of the reflected pulse, T = |/(Od///max is the effective duration of the reflected pulse, I{t) is the intensity envelope. FWHM durations of pulses presented here are somewhat shorter. In calculations, we assumed that multilayer structures consist of two alternating layers with ideal interfaces. We used the method of recurrent relations for the

85

calculation of the complex reflectivity amplitude of structures [11]. Optical constants of materials were taken from [12]. Compression of chirped XUV pulses. Intense chirped XUV pulses can be generated in the process of reflection and focusing of a source laser pulse by a flying plasma mirror [13]. The chirp of the XUV pulse can be controlled by the chirp of the source laser. Another possibility is to use a plasma with a density gradient as the speed of the flying plasma mirror depends on the density. Due to a small curvature radius of the flying mirror, the focal spot is situated inside the plasma region. The multilayer mirror can refocus the pulse to the desired point. hi the calculation, the incident pulse had a Gaussian form with the duration To = 2.5 fs and the chirp parameter b - -6.5 fs"^. The chirp was negative, so the leading part of the pulse had a higher frequency. This was consistent with the natural trend of a deeper penetration (hence, a longer delay) of the higherfrequency radiation into the mirror structure. The results of the calculation are shown in Fig. 1. The aperiodic mirror performed a 13-fold temporal compression with the energy reflectivity of 0.17. The peak intensity of the reflected pulse was more than twice the intensity of the incident pulse. ,

2

n 60

65

70

75

80 85 E,eV

90

95 100

I

,

5

.

.

.

.

J .

.

.

.

,

.

:

i

1

~

t"-

1

V"'

f-

|-J

i

i I

1.5 ~ 1, rel. u • 1 0.5

•

-4 !

^n . . . . t

"

i 1

1 ff

01 . 1 1r ^ , t,fs

1

" r

: -

.'VNX :::,r-r J

Fig. 1. Mirror for the compression of chirped pulses (Mo/Si, 80 monolayers, the incidence angle 5°). Left: the mirror reflectivity (thick line), the spectral phase (dashed line), the spectrum of the chirped incident pulse {hcoo - 86 eV, ro = 2.5 fs, b = -6.5 fs'^, thin line). Right: intensity envelopes of the incident (dashed line) and the reflected (solid line) pulses. T = 0.19 fs, the energy reflectivity 0.17

Simultaneous reflection of several high-order harmonics. It was recently shown that high-order harmonics of the laser radiation were not completely phased [2]. For harmonics generated by a TiiSapphire laser in Ar gas the emission time difference between two neighboring harmonics was measured to be A/ - te(q+2) 4(^) = 33 as. It is important to note that higher harmonics were emitted after lower ones. This means the positive chirp of the harmonics train, which is not consistent with the above-mentioned natural trend. To calculate mirrors for the simultaneous reflection of several harmonics, we set the incident train of pulses in the form Eo(t) = 2 ^ ^ cos(0)qt - OJ^At /4O)L) , where coq-qcoi^, so that the group delay was tg = cOgAt/(2coi) = qAt/2. We calculated a mirror for the reflection of odd harmonics from 25 to 69. Harmonic amplitudes a^ decreased exponentially with order from 1 to 0.1 (intensities from 1

86

to 0.01). The results of the calculation are shown in Fig. 2. The mirror performed a two-fold compression of pulses in the train. 0.5 I

....

0.4 0.3

az 0.1

A

i

30

40

:

;

4_

\

/

i

|rk

^ \

\

60

70 E,eV

80

: 20 15

\

Im K.n iIl.lM.lf AMt'.A II 50

r 25

:

J

i

90

, rel. u.

^ , rad 10

100

Fig. 2. Mirror for the simultaneous reflection of 25-to-69-order odd harmonics with an emission time difference of 33 as (Mo/Si, 80 monolayers, the incidence angle 5°). Left: the mirror reflectivity (thick line), the spectral phase (dashed line), the spectrum of the incident pulse (thin line). Right: intensity envelopes of the incident (thin line) and the reflected pulses (thick lines, scaled (x5) for convenience), TO = 0.27 fs, r = 0.13 fs, the energy reflectivity 0.11

Conclusion. We made a theoretical investigation of aperiodic multilayer mirrors for the reflection of ultrashort XUV pulses. We designed aperiodic structures for the 13-fold compression of negatively chirped XUV pulses and for the reflection of several high-order harmonics with different emission times. The use of aperiodic multilayer structures is indispensable for the further decrease in the pulse duration and the increase in the focused pulse intensity in the XUV spectral region. Acknowledgements. The work was supported by the Japan Society for the Promotion of Science (JSPS P-03543).

References 1 2 3 4 5 6 7 8 9 10 11 12

R. Kienberger et al. Nature 427, 817, 2004. Y. Mairesse et aL, Science 302, 1540, 2003. V. G. Kapralov et aL, Quantum Electron 32, 149, 2002. V. E. Levashov et aL, Flas. Phys. Reports 30,149,2004. J. F. Meekins et aL, Appl. Opt. 25,2757, 1986; ibid 26, 990, 1987. K. D. Joensen, Proc. SPIE 3113, 500, 1997. E. Ziegler et aL, Proc. SPIE 3737, 386, 1999. N. N. Kolachevsky et aL, Quantum Electron. 30, 428 2000. I. L. Beigman, A. S. Pirozhkov, E. N. Ragozin, JETP Lett. 74, 149,2001. I. L. Beigman et aL, J. Opt. A: Pure Appl. Opt, 4,433,2002. A. V. Vinogradov, ed., X-Ray Mirror Optics, Leningrad: Mashinostroenie, 1989. R. Soufli and E. M. Gullikson, Proc. SPIE 3113,222, 1997, http://cindv.Ibl. gov/optical constants/. 13 S. V. Bulanov, T. Esirkepov, T. Tajima, Phys. Rev. Lett. 91, 085001, 2003. 87

Route to design electric fields of optical pulses: A combination of a pulse shaper and a carrierenvelope-phase stabilized chirped-pulse amplifier system Masayuki Kakehata^ Hideyuki Takada\ Yohei Kobayashi^ and Kenji Torizuka^ Kazuki Nishijima^, Hiroaki Takamiya^, Tetsuya Homma^, and Hideo Takahashi^ ^ National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 2, 1-1-1 Umezono, Tsukuba 305-8568, Japan E-mail: [email protected] ^ Shibaura Institute of Technology, 3-9-14 Shibaura, Minato-ku, Tokyo 108-8548, Japan Abstract. We demonstrated active carrier-envelope-phase (CEP)-shift by utilizing a 4f-pulse-shaper in a CEP-stabilized chirped-pulse-amplification system. A combination of a pulse-shaper and CEP-stabilized pulses enables us to design electric fields, both the pulse envelope and the carrier-envelope relation.

1. Introduction The carrier-envelope phase (CEP) is the relative phase between the peak of the pulse envelope and the electric field; it is important in controlling the high-order harmonic generation and measuring attosecond phenomena. CEP-stabilized chirped-pulse amplification (CPA) systems are demonstrated [1, 2]. To control the CEP for pump-probe experiments, an active CEP shifter giving no effects on the pulse envelope and delay is desirable. We demonstrate an active CEP-shifting device employing a 4f-pulse shaper. A combination of the pulse shaper and the CEP-stabilized system will allow us to design the shape of the electric field (both the pulse shape and the carrier-envelope phase) of optical pulses.

2. Experiments Performance of a pulse shaper as a CEP shifter Figure 1 (a) depicts the spectral interferometry setup to test the CEP shifter. We measured the spectral interference (SI) between the reference pulse and the pulse passing through the pulse shaper. The CEP of the Ti:sapphire oscillator was not stabilized. The pulse shaper is composed of a liquid-crystal spatial light modulator (SLM) and the 4-f optical configuration. First, we measured the SI to obtain the phase difference ^i (a))=^rb,o (o))^ef (o) with giving a certain phase by SLM. Second, we applied periodic phase modulation generated by SLM and measured the phase difference

88

^ (o, t)f ^rb(o), t)-^ef. (©)• Then we calculated the phase shift ^s(o>) t)=^(o), t)^((o), then fit a linear function to ^sC®? t) in the co-if) domain and derived the time delay and the CEP shift as shown in Fig. 1(b) [3]. Pulse shaper (CEP shifter)

(b)

•f-

^

CEP shift

4

h^co) TO

^

^-2

S l o p e ; Delay shift % ''p^"

1x10 2x10 Angular frequency (rad/s)

3x10

Fig.l (a) Experimental setup to test the CEP shifter. CM: cylindrical mirror (^242mm). CEP of the input pulse {^) is not stabilized (b) Relation between the relative spectral phase and the CEP and the time delay Figure 2 shows the relative CEP-shift and delay shift fi)r (a) without phase modulation, (b) sinusoidal delay shift by a PZT, and (c) smusoidal CEP-shift by the pulse shaper. The delay-shift and the CEP-shift agreed with the applied shift within the experiment accuracy. Without modulation

(b)

(c)

./^Vy-N A

A A A

A

y V V V V Fig.2 Change of the CEP-shift and delay-shift. Measured (a) without modulation, (b)with sinusoidal delay modulated applied by the delay line in the interferometer, and (c) with sinusoidal CEP modulation by the pulse shaper. CEP control of chirped-pulse amplified pulses by the pulse shaper We installed the pulse shaper in a CEP-stabilized CPA system [2] and measured the CEP-shift by the self-referencing f-to-2f SI method [4]. Figure 3 illustrates the experimental setup. The amplified pulse is ImJ/pulse with the spectrum width of 20 nm FWHM, which corresponds to a 50 fs FWHM transform-limited pulse. The exposure time was 21msec, and the repetition rate of the amplifier was 555 Hz. Figure 4(a) was obtained by applying rectangular CEP-modulation at 0.5Hz; (b) was with a triangular CEP-modulation at 2Hz. The applied CEP modulations were clearly observed in the/^ro-2/SI, which confirms that the pulse shaper works as an active CEP shifter. Furthermore, because the pulse shaper can apply a desired relative phase and the desired CEP shift, a combination of a CEP stabilized system and a pulse-shaper can generate a designed electric field, a complicated envelope shape with controllable CEP.

89

: = 80 M H z —n 3 5 fs

T

i C E P shifts r

Pulse

selec

!_:!_^

3L

I H O HOW

(G fa t i n g s ) ! ^ > 220

fibe rj

ps

R e g e n . a m p Synch. I

I

R 9 a dy pjUse

i

|Do'ay|

D rv Id e r i CEO

stabilized

oscillator

^-j

T"

A m p l i f i e r s ta g e

Fig.3. Diagram of a CEP-stabilized, chirped-pulse amplification system with CEP sliifler. (a)

(b)

W a v e l e n g t h (nm )

Fig.4. Self-referencing SI fringe measured with applying CEP modulation by the pulse shaper. (s) Rectangular CEP modulation at 0.5Hz, (b) triangular CEP shift at 2 Hz.

3. Conclusion We demonstrated active carrier-envelope phase shifter using a 4f-pulse shaper. A combination of a pulse shaper and a CEP-stabilized CPA system will allow us to design electric fields of optical pulses. Acknowledgements. A part of this study was financially supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology, based on screening and counseling by the Atomic Energy Conamission, Japan.

References 1 A. Baltuska, Th. Udem, M. Ulberacker, M. Hentschel, E. Goullelmakis, Ch. Gohle, R. Holzwarth, V. S. Yakovlev, A. Scrinzi, T. W. HSnsch and F. Krausz, Nature. 421, 611-615 (2003). 2 M. Kakehata, H. Takada, Y. Kobayashi, K. Torizuka, H. Takamiya, K. Nishijima, T. Homma, H. Takahashi, K. Okubo, S. Nakamura, Y. Koyamada, Optics Express 12,2070-2080 (2004). 3 AW. Albrecht, J. D. Hybl, S. M. Gallagher Faeder, D. M. Jonas, J. Chem. Phys. 111,10934-10956(1999). 4 M. Kakehata, H. Takada, Y. Kobayashi, K, Torizuka, Y. Fujihira, T. Homma, and H. Takahashi, Opt. Lett. 26, 1436-1438 (2001).

90

Towards electric field reconstruction using coherent transients in a two-level system A. Monmayrant, B. Chatel and B. Girard Lab. Collisions Agregats Reactivite, CNRS UMR 5589, IRSAMC, UPS, 118 route de Narbonne. 31062 Toulouse, France E-mail: [email protected]

Abstract: Interaction between a two-level system and a weak chirped pulse leads to oscillations of the excited state amplitude, named "coherent transients". Their extreme sensitivity to the pulse shape provides a tool for electric field measurements.

1. Introduction One-photon transition in the weak field regime results in a linear interaction for which the final state populations can be entirely deduced from the power spectrum. However, the phase of the wave function is sensitive to the electric field. This can have important consequences for applications where a subsequent excitation is performed, in particular when coherent superpositions are involved. The transient evolution of excited state population is also strongly dependent on the detailed laser shape. As an intuitive illustration of this statement, the transient response to a non-resonant excitation follows the electric field pulse envelope, independently of its spectrum. For instance, simply changing the pulse duration will change this transient response. A resonant interaction leads to radically different behaviors. FT limited pulses produce a step-wise excitation in the weak-field, and Rabi oscillations in the intermediate and strong field regime. Chirped pulses produce a total population inversion in the strong field with a final state robust with respect to small variations of laser parameters. Chirped pulses in the weak field lead to Coherent Transients (CT). The laser frequency sweeps linearly with time and crosses the resonance. Most of the population transfer occurs at resonance. The small fraction of excited state amplitude transferred after resonance leads to strong oscillations due to interferences between the atomic dipole and the exciting field. On the other hand, interaction before resonance results in negligible effects [1]. Similarly, interferences between the field radiated by the atom and the incoming field leads to interferences which can be used to a partial analysis of the field [2]. The shape of Coherent Transients can be radically changed by shaping the pulse [3]. The high sensitivity of CT to slight modifications of the laser pulse [4] opens the possibility of characterization of the laser pulse itself. In a simple approach, if the general shape of the laser pulse is known and only few parameters need to be determined, one can use a simple adjustment of these parameters to fit the experimental curve with the predicted one. However, one would like to establish a general method able to determine any pulse shape. Using the CT needs to have a dominant quadratic spectral phase. It can be added to the pulse if

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necessary. One difficulty is that only the part of the pulse after resonance leads to oscillations which can be used to determine its shape. Another difficulty is that the measured quantity is related to the excited state probability whereas the probability amplitude, proportional to the integral of the laser electric field, is not directly measured. However it is possible to overcome these difficulties by combining several CT measurements.

2. Experimental Set-up Atomic rubidium is used as a benchmark system. The 5s - 5p (P1/2) transition (at 795 nm) is resonantly excited by a sequence of a Fourier limited and a chirped pulse produced by a Regen amplifier. The transient excited state population is probed "in real time" on the (5p - ns, n'd) transitions with an ultrashort pulse (at 607 nm, 30 fs, Non-collinear Optical Parametric Amplifier (Nc-OFA)) compressed with chirped mirrors. The pump pulse sequence is produced by a programmable pulse-shaping device, recombined with the probe pulse and sent into a sealed rubidium cell. All the experiments are performed in the perturbative regime. The pump-probe signal is detected by monitoring the fluorescence at 420 nm due to the radiative cascade (ns,n'd) -> 6p -> 5s collected by a photomultiplier as a function of the pump-probe delay. The pulse shaping device is a 4f set-up composed of one pair each of reflective gratings and cylindrical mirrors. Its active elements -two 640 pixels liquid crystal mask- are installed in the common focal plane of both mirrors [5]. This allows for phase and amplitude shaping.

3. Results In order to observe oscillations on the whole pulse duration, the excited state must be initially populated so that interferences are present from the beginning until the end of the interaction between the chirped pulse and the atom. This is achieved with a sequence of two pulses with a well defined phase relationship. The high resolution of the pulse shaper allows generating these two pulses by applying a complex transmission H^^cd) in the spectral domain: H^{co) = \ + Qx^[i[d + (p\co-co^) + (l)\(o-co^y

/2)\

The first pulse is short (FT limited) and the second one is strongly chirped with f = 2.10'fs' in order to exhibit the CT, and delayed by / = 4ps. The first part of the second pulse (before resonance) produces interferences with the population excited by the first pulse as can be observed in Fig. 1. This scheme provides interferences on the whole duration of the second pulse. Two measurements are performed for ^ = 0 and 6 = njl. The combination of these two measurements allows one determining in-phase and in-quadrature contributions from the second pulse, so that the excited state probability amplitude produced by the second pulse can be deduced from this set of measurements. For a second pulse weaker than the first one, this inversion is linear with respect to the second pulse. For any relative intensities (between the first and second pulses), the inversion procedure is

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nonlinear but still possible. The result of this inversion is shown in Fig. 2 which displays in the complex plane the reconstructed excited state probability amplitude a^{t) resulting from the second pulse.

Delay (ps)

Fig. 1: CT resulting from a FT limited pulse followed by a chirped pulse. In the second measurement, an extra phase shift of TT/l is applied to the second pulse. Solid line: theory, dots: experiment.

-0.2-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Re(a,(t)) (au)

Fig. 2: Reconstructed probability amplitude ^e{^) deduced from the combination of the two measurements presented in Fig. 1. The Cornu spiral appears clearly. Top: theory; Bottom: experimental result

References S. Zamith etaL, Phys. Rev. Lett. 87, 033001 (2001). J. E. Rothenberg and D. Grischkowsky, J. Opt. Soc. Am. B 2, 626 (1985); J. E. Rothenberg and D. Grischkowsky, J. Opt. Soc. Am. B 3, 1235 (1986); J. E. Rothenberg, IEEE J. Quant. Electronics QE-22,174 (1986). J. Degert etal, Phys. Rev. Lett. 89, 203003 (2002). W. Wohlleben etal, Appl. Phys. B 79, accepted (2004). A. Monmayrant and B. Chatel, Rev. Sci. Instr., accepted (2004).

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Spatiotemporal determination of the absolute phase of few-cycle laser pulses Fabrizio Lindner\ Michael Schatzel\ Gerhard Paulus^'^' , Herbert Walther\ Andrius Baltuska^' , Eleftherios Goulielmakis^'*, Matthias Lezius ' , and Ferenc Krausz ' ^ Max-Planck-Institut fiir Quantenoptik, Hans-Kopfermann-Str. 1, 85748 Garching, Germany ^ Department of Physics, Texas A & M University, TX 77843-4242, College Station, Texas, USA ^ Sektion Physik, Ludwig-Maximilians-Universitat Munchen, Am Coulombwall 1, 85748 Garching, Germany "* Institut fiir Photonik, Technische Universitat Wien, Gusshausstr. 27, 1040 Wien, Austria ^ Institut fiir lonenphysik, Universitat Innsbruck, TechnikerstraBe 25, 6020 Innsbruck, Austria Abstract. We determined the carrier-envelope ("absolute") phase of linearly polarized fewcycle laser pulses by measuring the energy-resolved asymmetry of electron emission from noble gases. The Gouy phase shift in the laser focus is also measured, providing the first full spatiotemporal depiction of the electric field in the whole focal region.

Atomic processes induced by ultrashort laser pulses have recently attracted a lot of attention, in particular owing to their potential of generating isolated attosecond light pulses [1,2]. For these exciting prospects, few-cycle laser pulses, i.e. pulses consisting of merely a few electromagnetic oscillations, are necessary. The electric field of such laser pulses can be written as E(t) = e^' Eo(t) ' cos{cot -\-cp)

(1)

where e^ denotes the axis of polarization, EQ(t) the envelope of the pulse, co the carrier angular frequency of the laser, and cp the phase between the carrier and the envelope, often called carrier-envelope (CE) or, more directly, "absolute" phase. With respect to the latter, the convention in (1) implies that cp = 0 corresponds to a "cosine-like" pulse with the absolute maximum of the electric field pointing to the positive direction. Accordingly, cp = ± nil correspond to "sine-like" pulses. The absolute phase cp plays a major role in any atomic process driven by few-cycle laser pulses [3,4]; however, complete control over it was demonstrated only very recently [4-6]. Due to the influence of the absolute phase on the laser's electric field shape, nonlinear photoionization is a possible approach to determine its value. In our experiments noble gas atoms (typically Xe) were ionized with peak intensities of nearly 10^"^ W/cm^ by linearly polarized few-cycle pulses [6]. A detailed description of the experimental setup can be found in [5,7]. In short, electron

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spectra originating from a well-confined focal area are simultaneously recorded in the two opposite polarization directions ("stereo-ATI") by means of time-of-flight spectroscopy. The energy-resolved left-right asymmetry can be used to retrieve the phase value. The phase-stabilized laser system [6] delivers pulses characterized by identical electric-field waveforms. Therefore, pulses with known phase differences Acp can be obtained by simply delaying the envelope with respect to the carrier in front of the experiment. Glass dispersion is an immediate way of achieving this: At a central wavelength of 760 nm adding 52 //m of fused silica change cp by 2jt without affecting the pulse duration distinctly. Thus, two glass wedges, which can be shifted with respect to each other, allow adjusting any phase. The electron spectra detected for different CE phases significantly differ in many aspects, the most striking being the high-energy part (ATI-plateau). The latter is shown in Fig. 1. for several absolute phases, separately for the detector located on the left and on the right side of the laser focus. Both semiclassical and quantum mechanical models [8] yield the basic result that the most energetic photoelectrons are mainly emitted in the direction of the peak of the electric field. Thus, the clear phase dependence of the cutoff position gives a direct read-out of the electric-field strength in the respective direction, i.e. it allows absolute phase determination. One can verify that Acp = n corresponds, as expected, to a change from left to right while Aq) = 2n exactly reproduces the spectra. Note that these results remove the jt ambiguity intrinsically connected with high-harmonic generation experiments [4]. An important issue of nonlinear processes driven with few-cycle laser pulses is that they typically take place in a laser focus. It is known that an electromagnetic beam propagating through a focus experience an additional JT phase shift with respect to a plane wave [9]. The effect of this so-called Gouy phase anomaly on the spatial dependence of the absolute phase is of critical importance for experiments taking place over an extended area of the focus, e.g. high-order harmonic generation and attosecond pulse generation. RIGHT

LEFT

10^

10^

0

Jt

absolute phase [rad]

2jt

0

Jt

2jt

MO^

absolute phase [rad]

Fig. 1. Electron count rate in the high-energy part of the ATI spectra as a function of electron energy and absolute phase for the two detectors

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In order to analyze in detail the phase variation within the focal range, we acquired several electron spectra corresponding to different positions along the beam propagation direction. Two thin slits perpendicular to the beam axis and to the polarization axis allow selecting electrons originating from a well confined focal area. Then, the absolute phase value can be determined at each position by inspecting the corresponding left-right asymmetry in the recorded spectra. Figure 2. shows the retrieved absolute phase as a function of the propagation distance in the laser focus [7]. For comparison, the Gouy phase of a Gaussian beam with the nominal focusing parameters of our experiments is also shown. Note that the absolute phase shift is not expected to follow precisely the Gouy phase, the latter being a property of cw lasers. The pulses undergo the Ji phase shift within a few Rayleigh distances and, what is particularly important for experiments, the phase does not exhibit any wiggles or irregularities. These results constitute the first full characterization of few-cycle optical pulses in space and time, an essential step for any application of such laser systems.

-

^

CD Q.

B-' \ -2

0

^

: 2

propagation distance [mm] Fig. 2. Measured carrier-envelope phase variation as a function of the propagation distance in the focus due to the Gouy effect [5]. The solid line is the Gouy phase shift of a cw Gaussian beam, shown for comparison

Acknowledgements. This work has been supported by the Austrian Science Fund (Grants No. F016, No. Z63, and No. P15382) and by The Welch Foundation (Grant No. A-1562).

References 1 2 3 4 5 6

M. Hentschel et al, Nature 414, 509, 2001. R. Kienberger et al., Nature 427, 817, 2004. G. Paulus et al., Nature 414, 182, 2001. A. Baltuska et al.. Nature 421, 611, 2003. G. Paulus et al., Phys. Rev. Lett. 91, 253004, 2003. A. Baltuska et al., IEEE Journal of Selected Topics in Quantum Electronics 9, 972, 2003. 7 F. Lindner et al., Phys. Rev. Lett. 92, 113001, 2004. 8 D. Milosevic et al.. Optics Express 11, 1418, 2003. 9 L. G. Gouy, C. R. Acad. Sci. Paris 110, 1251, 1890.

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Spatial chirp and pulse-front tilt in ultrashort laser pulses and their measurement Selcuk Akturk^ Xun Gu^ Erik Zeek* and Rick Trebino^ ^ School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA E-mail: [email protected] Abstract. We show that two physically different definitions of spatial chirp exist. We also show that pulse-front-tilt arises, not onlyfromangular dispersion, but alsofromspatial and temporal chirp. We verify these results using GRENOUILLE.

1.

Introduction

Spatio-temporal distortions are common in ultrafast optics. One such distortion is angular dispersion (AD), which is often introduced by using a dispersive element such as a prism or grating. Propagation of an angularly dispersed beam will induce spatial chirp (SC). Angular dispersion also causes pulse-front tilt (PFT) and indeed it has been previously shovm that PFT and AD are equivalent [1]. In this work, we show that AD and PFT are not equivalent, and we provide an additional source of PFT, in which no AD occurs. We also show that there are actually two different SC definitions. We then use our simple version of frequency-resolved optical gating (FROG), GRENOUILLE, to measure, not only the pulse intensity and phase, but also the spatial chirp and pulse-front tilt. Consider an initially transform-limited, but spatially chirped beam—^with no AD—passing through a dispersive medium (Fig. 1). Due to group-velocity dispersion in the medium, the redder side of the beam emerges from the medium earlier than the bluer side, resulting in PFT in the output beam. Because no angular dispersion occurs, this violates the well-known AD/PFT duality. Spatially chirped pulse with pulse-front tilt, but no angular dispersion Vg(red)>Vg(blue)

Fig. 1. Two sources of pulse-front tilt. Left: The well-known angular dispersion. Right: The combination of spatial and temporal chirp, which causes PFT without AD. In order to understand this effect, it is important to also understand spatial chirp, which we show can take two different forms. One involves writing the spatial chirp in terms of the variation of the beam center position (XQ) with

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frequency a)\ ^ = 6XQIACO which we will call the spatial dispersion. Another involves writing the spatial chirp in terms of the variation of the pulse center frequency {COQ) with position x: V^ACOQI&K, which we call XhQ frequency gradient, A Gaussian beam with spatial dispersion ^ can be written: E (jc, (D) = E^ {(D) exp f- {x - C(^)^ 1^^ 1 (1) A beam v^th frequency gradient v, on the other hand, is of the form: \E{X,CO)\=f{x)\E,{a)-vx)\

(2)

If we also assume a Gaussian pulse in time or frequency, it is easy to find: E, {m) = E, exp(-fi>VoV4),

u = C/{C' + ^ \ ' A)

(3)

The two SC parameters do not correlate monotonically, and they have different physical meanings (Fig. 2). Spatial dispersion ^ arises directly from propagation with AD, and it describes globally how far different frequency components separate, while frequency gradient v describes the local variation of the spectrum.

2

3 4 Position [mm]

5

5

10 i:, [nm-fs/rad]

Fig. 2. (left) Experimental spectrum vs. position. The black and blue lines are x^ {X) and XQ{X) plots, respectively. Using the slopes of these plots, ^ is calculated to be 3.9x10^ nm-fs/rad, and v 3.3x10"* rad/nm-fs. With the measured w and TQ, Equation 2 is verified within 6% error, (b) Theoretical plot of ^ and v with the above w and r^. To see understand the role of SC in PFT, we also include angular dispersion {/}) and linear chirp ( ^ ) in the pulse/beam and inverse Fourier transform from the (x,(o) domain into the {xj) domain to obtain: ^ ( ^ , 0 = /Wexp[-(^"-^o)'A']exp[-i^i(^-/o)-i(^ ratio of the pulses in the probe light. From the image, we can see directly that the pulsed light eventually becomes focused. Nevertheless, the intensity of the pulse, i.e., the brightness of the profile in Fig. 1(a), gradually decreases with the object pulse propagation; this fact implies that before reaching the focal region, the object pulse loses a part of its energ}^ because of multiphoton absorption and/or ionization-induced refraction. For comparison, the plasma profile is also shown in Fig. 1(e), where the background is subtracted. Other observations under the same experimental conditions are shown in Figs. l(b)-(d). These profiles seem to be different from one another. (The difference can clearly be recognized by a false-color illustration.) Since the profiles were integrated over 2,000 shots, the shot-to-shot fluctuation of the laser light source is sufficiently canceled out. Hence, the difference of the profiles is probably due to atmospheric turbulence [3]. Here, we confirmed that the plasma profile was hardly changed according to the measurement.

3.

Conclusion

In conclusion, we succeeded in obser\dng instantaneous intensity distributions of 0.49-mJ, 45-fs (i.e., 10-GW peak power) optical pulses propagating in air by integrating multiple shots. Since the probe light was composed of an octuple pulse train, eight-frame images were captured at a stretch; the time resolutions of the respective frames were of a femtosecond scale, and the time intervals between adjacent frames were of a subpicosecond scale. The obtained eight-frame FTOP image showed not only the pulse Qncrgy reduction due to a laser-induced plasma, but also the propagation-profile variations due to the turbulence of the atmosphere. The image data clearly show that FTOP can be utilized for real-time monitoring of propagation of femtosecond optical pulses generated by a regenerative amplifier system. Acknowledgements. The authors would like to thank T. Hiruma, Y. Suzuki, and Professor S. Nakai for their encouragement.

References 1 For example, M. Fujimoto, S. Aoshima, and Y. Tsuchiya, Meas. Sci. Teclinol. 13, 1698,2002. 2 M. Fujimoto, S. Aoshima, and Y. Tsuchiya, Opt. Lett. 27, 309, 2002. 3 V. P. Kandidov, O. G. Kosareva, M. P. Tamarov, A. Brodeur, and S. L. Chin, Kvant. Elektron. 29, 73, 1999 [Sov. J. Quantum Electron. 29, 911, 1999].

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Self-referenced measurement of the complete electric field of ultrashort pulses in time and space Pablo Gabolde, Selcuk Akturk, and Rick Trebino Georgia Institute of Technology, 837 State St NW, Atlanta GA 30332, USA E-mail: [email protected] Abstract. We propose and demonstrate a technique based on Fourier-synthesis digital holography andfrequency-resolvedoptical gating to measure the complete spatiotemporal behavior of potentially arbitrary ultrashort laser pulses.

1.

Introduction

Ultrashort-pulse measurement techniques usually ignore the pulse's spatial dependence. This representation conceals the possible coupling between space and frequency, or space and time, although such couplings are commonly used in pulse compressors, stretchers and shapers, and may subsequently appear as distortions in the pulse. Recently, we showed that frequency-resolved optical gating (FROG) can identify first-order spatiotemporal effects, but in only one spatial direction [1, 2], and occasionally ultrafast techniques, such as spectral interferometry, are extended to one transverse spatial dimension [3]. Currently, however, there does not exist a self-referenced technique that can measure the complete pulse electric field in space and time, E(x,y,z,t). Rather than extending time-domain techniques into the space domain, we will extend space-domain techniques into the time, or rather, frequency, domain. Intensity-and-phase spatial-beam measurements (e.g., holography and wave-front sensors [4]) have achieved great sophistication. Unfortunately, they either require an independent reference pulse [5] or are restricted to transform-limited pulses in time [6]. Here we combine Fourier-synthesis digital holography [7] with FROG to achieve true self-referenced four-dimensional measurements of the field of potentially arbitrary pulses, E(x, y, z, /).

2.

Method

First, because the electric field satisfies the wave equation, we note that it is sufficient to measure E(x,y,t) or Ej^x^y.o)) at a given position z = ZQ along the propagation axis. Then, to obtain E{x,y,co\ we perform a set of holographic measurements at discrete frequencies. A set of narrow band-pass filters is used to isolate the frequency components of the pulse. This yields the essentially monochromatic spatial complex field, E(x,y,a)) for each frequency cok, whose amplitude and phase must be measured. Different methods are available, but off-

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axis digital holography [8] offers a convenient and inexpensive way to reconstruct the 2-D spatial amplitude and phase of monochromatic light from a single digital interferogram. We use the beam itself as the reference beam, which we spatially filter in order to obtain a spherical wave, whose spatial amplitude and phase are therefore known. The direct algorithm to extract the amplitude and phase of the object beam from the digital hologram is well established [9]. The relative phase of each frequency component is not determined, however, due to the self-referencing. Therefore we perform an additional FROG measurement over a small spatial portion of the beam, but without any band-pass filter, to correctly set the relative phase of each monochromatic field, E(x,y,C0f^), Then we fully reconstruct the complex field in the time domain using an inverse Fourier transform: 1 In

1

(1)

3. Coupling between space and frequency: spatial chirp Perhaps the coupling that occurs most often is the one between space and wavelength, which has been called spatial chirp. If one considers the functions XQ(X) and y^QC) to be the center position of the beam at a given wavelength, then spatial chirp can be described by the variations of JCQ and JO with l. We introduced spatial chirp with a pair of prisms arranged to cancel angular dispersion, then measured E(x,y,co) by the method presented in section 2, before computing xo(co) and yo(co). Our results are presented in Fig. 1. Our spatial chirp measurement (Sx:o/9A = 27|im/nm) agrees with the results obtained from a spatially resolved spectrum. As expected, we only found a significant spatial chirp along the jc-coordinate (parallel to the prisms base).

770

rao

7S0

800

810

Fig. 1. Spatial chirp measured for the same pulse according to two possible representations. Left: central position of the intensity of each spectral component. Right: Spatial profile of the pulse. The vertical axis corresponds to the intensity I(x^) of the pulse, and color to the local average wavelength AO(JCJ^).

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4. Coupling between space and time: pulse-front tilt Gur technique also easily reveals pulse-front tilt, which arises from the coupling between space and time and must be computed from the intensity \E(x^,t)f in the time domain. Once \E(x,y,t)f has been computed, one can define tihe arrival time, to(x,y), of the maximum of |E(jc,;;,Of at a given position, so that pulse-front tilt along X is just dto/dx. Using our method, we measured the complete spatio-temporal field of pulses with varying amounts of pulse-front tilt (see Fig. 2).

X[tmil

Fig. 2. Pulses with minimal (left) and significant (right) pulse-front tilt. Arrival time to(xy) is plotted against the vertical axis, and color represents the instantaneous wavelength Ao(;cj;).

References 1.

2. 3.

4. 5.

6. 7.

8. 9.

S. Akturk, M. Kimmel, P. O'Shea, and R. Trebino, "Measuring spatial chirp in ultrashort pulses using single-shot Frequency-Resolved Optical Gating," Optics Express 11, 68-78 (2003). S. Akturk, M. Kimmel, P. O'Shea, and R. Trebino, "Measuring pulse-front tilt in ultrashort pulses using GRENOUILLE," Optics Express 11,491-501 (2003). L. Gallmann, G. Steinmeyer, D. H. Sutter, T. Rupp, C. laconis, I. A. Walmsley, and U. Keller, "Spatially resolved amplitude and phase characterization of femtosecond optical pulses," Optics Letters 26,96-98 (2001). B. C. Piatt and R. Shack, "History and Principles of Shack-Hartmann Wavefront Sensing," Journal of Refractive Surgery 17, S573-S577 (2001). T. Tanabe, H. Tanabe, Y. Teramura, and F. Karmari, "Spatiotemporal measurements based on spatial spectral interferometry for ultrashort optical pulses shaped by a Fourier pulse shaper," Journal of the Optical Society of America B 19,2795-2802 (2002). E. Arons, D. Dilworth, M. Shih, and P. C. Sun, "Use of Fourier synthesis holography to image through inhomogeneities," Optics Letters 18,1852-1854 (1993). E. Leith, C. Chen, Y. Chen, D. Dilworth, J. Lopez, J. Rudd, P. C. Sun, J. Valdmanis, and G. Vossler, "Imaging through scattering media with holography," Journal of the Optical Society of America A 9,1148-1153 (1992). S. Grilli, P. Ferraro, S. De Nicola, A. Finizo, G. Pierattini, and R. Meucci, "Whole optical wavefields reconstruction by Digital Holography," Optics Express 9,294-302 (2001). M. Takeda, H. Ina, and S. Kobayashi, "Fourier-transform method of fringe-pattem analysis for computer-based topography and interferometry," Journal of the Optical Society of America 72,156-160 (1982).

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Pulse-measurement challenges at 1.5 microns: several-cycle pulses and several-element devices Selcuk Akturk^ Mark Kimmel^ and Rick Trebino\ Sergey Naumov^ Evgeni Sorokin^ and Irina T. Sorokina ^ School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA E-mail: [email protected] ^ Institut fur Photonik, TU Wien, Gusshausstr. 27/387, A-1040 Wien, Austria E-mail: [email protected] Abstract. We have demonstrated frequency-resolved optical gating (FROG) for measuring several-cycle 1.5-micron pulses using an angle-dithered-crystal geometry. We have also demonstrated experimentally a very simple GRENOUILLE device for measuring fewhundred-fs 1.5-micron pulses using the nonlinear-optical crystal Proustite.

1.

Introduction

Extremely broadband several-optical-cycle pulses near telecommunication wavelengths (-1.5 jLtm), are in high demand for numerous applications [1]. Mode locked fiber lasers can also generate moderately intense pulses (-lOOfs) useful for nonlinear optical applications besides telecommunications. Reliably generating and utilizing such NIR pulses requires reliable measurement techniques. In this work, we describe two different frequency-resolvedoptical-gating (FROG) [2] devices. The first utilizes an angle-dithered rather thick crystal, which avoids the phase-matching bandwidth problems, to measure several-cycle pulses at 1.5 |im. The second is an ultrasimple GRENOUILLE device, which uses a thick crystal's small phase-matching bandwidth to spectrally resolve the pulse. This is a challenge at 1.5-|Lun wavelengths, where dispersion is minimal. However, we have used a more dispersive nonlinear crystal, Proustite, which nicely yields pulse measurements from 100 fs to a few ps.

2. Several cycle NIR pulse measurements With FROG, it is possible to measure pulses over a wide range of wavelengths, pulse lengths, and complexities. However, FROG has not yet been used for several-cycle IR pulses. Thus, in this work, we engineer a FROG device, which combines several recent innovations, for measuring such pulses. All pulse-measurement techniques require the use of a nonlinear-optical process, phase-matched over the pulse bandwidth, requiring very thin crystals for broadband pulses. However, we have recently shown that angle-dithering a SHG crystal yields a significantly increased effective phase-matching bandwidth [3]. Because the SHG efficiency scales as the square of the crystal thickness, angle-

112

dithering also yields significantly greater signal strength. While angle-dithering avoids the phase-matching requirement, the SHG crystal cannot, however, be arbitrarily thick due to group-velocity dispersion (GVD). We find that 1-mm LiNbOg and LiI03 crystals have negligible GVD for several-optical-cycle pulses. We used a KLM Cr'^'^iYAG laser yielding pulses with - 110 nm of bandwidth near 1.55 juim [1] with 50 mW of average power at a 100 MHz repetition rate. In our FROG, we used a 1-mm LilOg crystal, mounted on a resonant scanner, oscillating at 30 Hz with an amplitude of 10°. The pulses were split and combined using a 177°-apex-angle Fresnel biprism, which automatically splits the pulse into two and ensures their temporal and spatial overlap in the crystal. A 10-mm cylindrical mirror yielded a line focus along the delay axis. The resulting SHG signal was imaged onto the slit of a spectrometer, the output of which was recorded by a CCD camera and the intensity and phase retrieved from the resulting FROG traces using the Femtosoft SHG FROG code. Figure 1 shows the measured and retrieved FROG traces, as well as the retrieved and independently measured spectra, all of which are in very good agreement with each other. Temporal Intensity and Phase

^

1-0

1-0.8 ^

0.8-

r-^-^ -

0.6-

Temporal / ^ Intensity / \ Temporal / \ Phase / \

--5.4 --5.6 -5.8 -6.0 "6.2 -6.4

1-°^ f 0.4 0 . I 0.2~

0.0

j/: -40

-"V 0

Tl zx a> Q.

40

Time [fs] Spectral Intensity and Phase

1300

1400

1500

1600

1700

Wavelength [nm]

Fig.l: FROG measurements of Cr4+:YAG laser. Retrieved pulse width is 37.1 fs (FWHM).

3. GRENOUILLE for longer 1.5-micron pulses Fiber lasers in general have much less bandwidth than the C/^:YAG lasers. Thus it should be easier to measure them. Indeed, we have designed a very simple GRENOUILLE [4], an experimentally simpler version of FROG to do so. This involves the use of a thick SHG crystal^—thick enough that its finite phasematching bandwidth is able to resolve the spectrum of the second-harmonic signal. We have found that, for fiber laser pulse measurements, an exotic crystal, "Proustite," matches GRENOUILLE's requirements perfectly. We built a GRENOUILLE using the conventional setup [4]. To expand the beam we used a 5x magnification telescope. The beam then passed through a 75mm focal length cylindrical lens. We used a l^O*^ apex-angle Fresnel-biprism, in order to generate large enough delay range. The signal was mapped onto the cam-

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era by using a 50-mm cylindrical and 50-mm spherical lens doublet. The trace was recorded by a CCD camera and the intensity and phase retrieved from the resulting FROG traces using the Femtosoft SHG FROG code. In order to test our device, we used a Menlo Systems TC-1550-B fiber laser, operating at 1570 nm with an output power of 20.5 mW (25 MHz rep. rate). Figure 2 shows the measured and retrieved GRENOUILLE traces. For comparison, we also measured the same pulses using a conventional multi-shot FROG and we obtained excellent agreement between the two measurements (Fig.3).

-1QQD

T D 1000 De[ay [fs]

n—'—r 15S0 1500 1EQD Wavelength [nm]

-1D0D

0 1000 Delay [fsl Temporal livtei^sity ^\\r

1 ^-i 'jrw

yoduteted pulses

100 ns

CD

c cc JZ

13 ns

o TO

T\

r 1

\ ''

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Fig 1. Experimental set-up for SE-SPIDER. — zero-order X/2 waveplate.

TFP —thin film polarizer.

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The phase retrieval algorithm for SE-SPIDER is a slight modification on the conventional SPIDER algorithm, and similar to the method used for Space-Time SPIDER characterizations [6].

3. Results and Discussion By way of proving the principle, we have used the SE-SPIDER technique to measure 100 fs, 10 nJ pulses from a mode-locked Ti:Sapphire laser. However, it should be noted that 100 fs pulses are far from the limit of the shortest pulses which could be measured with this technique. We estimate that with our current setup (1.2 m imaging spectrometer with a 600 1pm grating and a 512 element CCD camera) we could easily characterize sub-15 fs pulses, and with a less dispersive spectrometer, even shorter pulses would be accessible. For example, a 0.5 m imaging spectrometer with a 6001pm grating and 2048 element array could accommodate the sub-6 fs pulses measured by Gallmann, et. al. [7] in a single shot. As a general check of the technique, we measured a pulse before and after passing through a 4 cm slab of SF8 glass. The dispersion of the glass block measured this way, 5600 fs^ is in good agreement with the known value of 5575 fs^, which demonstrates the accuracy of the technique. The measurements are also in excellent agreement with the pulse measured using conventional SPIDER. The spatial dimension of the SE-SPIDER interferogram can also be exploited to gain information about the spatial dependence of the pulse spectrum. In figure 2 we show the SE-SPIDER interferogram of a pulse, which was spatially chirped by passing through a prism pair. The spectral density and phase profiles at two different spatial points in the beam, also shown in figure 2, show the presence of spatial chirp. The measured value of this chirp, 109 THz/mm, is in good agreement with that calculated for our prism configuration, 112 THz/mm. If the mechanism of space-time coupling is known, as in this case, this measurement constitutes a complete characterization of the space-time field. Such assumptions have been used before to provide characterization when a functional form can be assumed [8, 9].

128

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Fig 2. SE-SPIDER interferogram of a spatially-chirped pulse and the reconstructed fields for two different spatial slices. The spectral density and phase at spatial slice a are given by the solid and dotted lines respectively, while that for spatial slice b are given by the dash-dotted and dashed lines.

4. Conclusions We have demonstrated an interferometric technique for the complete characterization of ultrashort optical pulses with greatly reduced spectral resolution requirements which is therefore well suited for measuring very broadband fields. This technique, Spatially-Encoded SPIDER, is similar to the conventional SPIDER technique but employs a spatial, rather than spectral signal encoding and has an advantage of only requiring one replica of the pulse to be measured. The two-dimensional (space and frequency) trace allows reconstruction of the spatially-resolved temporal electric field, and can therefore be used to track chirp or more complex distortions.

References 1 C. laconis and LA. Walmsley, IEEE QE 35, 501-509 (1999). 2 R. Trebino, K. W. Belong, D. N. Fittinghoff, J. N. Sweetser, M. A. Krumbugel, B. A. Richman, and D. J. Kane, Rev. Sci. Instr. 68, 3277-3295 (1997). 3 J. Chilla and O. Martinez, IEEE J. Quant. Electron., 27,1228-1235 (1991). 4 K. C. Chu, J. P. Heritage, R. S. Grant, K. X. Liu, A. Dienes, W. E. White, and A. Sullivan, Opt. Lett., 20, 904-906 (1995). 5 D. T. Raid, IEEE J. of Quantum Electronic 35,1584-1589 (1999). 6 C. Dorrer, E. M. Kosik, and LA. Walmsley, Opt. Lett. 27, 548-550 (2002). 7 L. Gallmann, D. H. Sutter, N. Matuschek, G. Steinmeyer, U. Keller, C. laconis, and LA. Walmsley, Opt. Lett. 24,1314-1316 (1999). 8 C. Dorrer and I. A. Walmsley, Opt. Lett. 27,1947-1949 (2002). 9 S. Akturk, M. Kimmel, P. O'Shea, and R. Trebino, Opt. Exp. 11, 491-501 (2003).

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Full characterization of ultraviolet and visible 10-fs pulses with zero-additional-phase SPIDER p. Baum, S. Lochbrunner, and E. Riedle LS fiir BioMolekulare Optik, LMU Mtinchen, Oettingenstr. 67, 80538 Mtinchen, Germany Abstract: Zero-additional-phase SPIDER is a novel spectral shearing interferometry setup capable to characterize the temporal amplitude and phase of ultrashort pulses over an extremely wide wavelength region. We demonstrate the full characterization of ultraviolet and visible pulses with durations in the 10-fs regime. The scheme does not alter the unknown pulses and yields the pulse shape at the interaction point of a spectroscopic experiment.

1. Zero-additional-phase SPIDER Tunable femtosecond pulses in various spectral regions are essential for experiments on ultrafast physical and chemical processes. For the management of higher order chirp a full characterization of amplitude and phase is essential. Due to dispersive optics like sample cells and the dispersion of air the pulses are only short at one point in the beam path. Conventional characterization schemes like FROG [1] and SPIDER [2] do not characterize the pulses at the experiment since they split the beam before the actual characterization and introduce additional phase. In this contribution we present an unambiguous and highly sensitive scheme to overcome these limitations and demonstrate the full characterization of extremely short ultraviolet and visible pulses directly at the experimental interaction point. In conventional SPIDER (Fig. 1 a) the unknown pulse is split into two delayed replica and mixed with a chirped pulse in a nonlinear crystal [2]. The stretched pulse is considered monochromatic during the interaction with each short pulse. Two identical but spectrally sheared and temporally delayed replica result which interfere in a spectrograph. The interferogram contains the differences in spectral phase between pairs of shifted frequencies and can be directly evaluated to yield the spectral phase of the original pulse. An additional measurement of the power spectrum gives a full reconstruction of the time dependent electric field [3]. The pulse is characterized in the nonlinear crystal, i.e. after the beam splitter. In the novel ZAP-SPIDER [4] (Fig. lb) the unknovm pulse is guided into the nonlinear crystal without manipulation. Two frequency shifted replica of the unknown pulse are generated by mixing with two strongly chirped auxiliary pulses C0„+f2 6),)