Special Issue "Ultraintense Ultrashort Pulse Lasers"

Guest Editor
Prof. Dr. Reinhard Kienberger
¹ Fakultaet fuer Physik, Technische Universitaet Muenchen, E11 James Franck Strasse, 85748 Garching, Germany
² Max Planck Institut fuer Quantenoptik,Hans-Kopfermann-Str. 1, D-85748 Garching, Germany
Website: http://www.e11.physik.tu-muenchen.de/mitarbeiter/Kienberger
E-Mail: reinhard.kienberger@tum.de
Phone: +49 89 289 12837
Fax: +49 89 289 12838

Dear Colleagues,

Understanding nature in ever faster and smaller timescales, be it in atoms, molecules or solids, is a prerequisite for many new developments in physics, chemistry, biology, and technology—reaching from medical applications to energy-transforming and energy-storing devices. This goal calls for new tools and techniques. Basically all of them are based on the development of ultraintense ultrashort laser pulses. Coherent light at the extremes—in intensity and pulse duration—will offer completely new possibilities in research. It is obvious that the advent of ultrashort pulse free electron lasers (FELs), e.g., the Linac Coherent Light source (LCLS) with pulses on the fs-level having 10¹³ photons in the keV range per pulse, has opened the way for a plethora of experiments, e.g., in 4D imaging, inner-shell spectroscopy and many more. In order to achieve comparable features on a table-top scale, the development of “conventional” ultraintense ultrashort pulse lasers is pushed forward strongly. Laser driven electron acceleration—again being suitable for the injection into an FEL—laser driven ion acceleration, which can be directly used in medical applications, and non-linear processes like sum-frequency generation, difference-frequency generation or high-order hamronic generation make these lasers extremely powerfull for the generation of sources with photon energies ranging from the infrared to the x-ray and at a pulse duration down to attoseconds. While chirped-pulse-amplifiers have become standard and have been more and more improved over the last years, optical parametric amplification gets more and more promising since broad bandwidth—necessary for the generation of ultrashort pulses—can be preserved during the amplification process. In any case, the development over the laser years has been very successful: Near-single-cycle-pulses, control and stabilization of the carrier-envelope-phase, attosecond pulse generation, high energy laser-driven electrons are only a few examples, and—not to forget—charachterization methods like FROG, SPIDER etc.

The special issue of the journal Applied Sciences “Ultraintense Ultrashort Pulse Lasers” aims to cover recent advances in the development of lasers of any type (OPAs to FELS) and any wavelength range (IR to x-ray) which provide ultraintense ultrashort pulses.

Prof. Dr. Reinhard Kienberger
Guest Editor

Submission

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• ultrafast lasers
• ultrashort pulses
• optical parametric amplification
• chirped pulse amplification
• carrier-enverlope phase
• few-cycle pulses
• free-electron-lasers
• attosecond pulses
• laser driven electron-acceleration
• laser driven ion-acceleration
• FROG
• SPIDER

Type of Paper: Article
Title: Ion Acceleration and Plasma Jets Driven by a High Intensity Laser Beam Normally Incident on Thin Foils
Authors: M. Shoucri ¹, J.-P. Matte ² and F. Vidal ²
Affiliation: ¹ Institut de recherche d’Hydro-Québec (IREQ), Varennes, Québec, J3X-1S1, Canada; E-Mail: shoucri.magdi@ireq.ca
² INRS Energie et Matériaux, Université du Québec, Varennes, Québec, J3X-1S2, Canada
Abstract: Recent experimental results [1,2] have shown the advantage of thin targets for collimated ion acceleration with normally incident high intensity circularly polarized laser beams. We study this problem with an Eulerian Vlasov code [3] which solves the one-dimensional relativistic Vlasov-Maxwell equations for both electrons and ions. The laser wavelength λ is much greater than the initial scale length L_edge of the jump in the plasma density at the plasma surface (λ >> L_edge). We consider the case of a high density plasma where the plasma density is n/n_cr = 100. The normalized amplitude of the vector potential of the incident laser beam is a₀ = 25/√2, where 2a₀² = Iλ²/1.368×10¹⁸, I is the intensity in W/cm² and λ is the wavelength in microns. The laser pulse is Gaussian and only about a 10 cycles long. Radiation pressure acceleration results when the laser beam interacts with the electrons at the plasma surface via its ponderomotive pressure, producing a sharp density gradient at the target surface, which gives rise to a charge separation and an electric field which accelerates the ions and leads to the formation of a plasma jet. We compare cases where the initial plasma target thickness is of the order of 2c/ωp , few skin depths c/ωp, and several times thicker. The results show a more important acceleration of the ions in the first case. Fine analysis obtained by the Vlasov code shows important differences in the phase-space structures for the electrons and ions between these cases. Especially in the first case, important leak or ejection of electrons in front of the target is observed.

Type of Paper: Review
Title: A First Principles Theory of Grating Dispersion Delay Lines for Chirped-Pulse Amplifier
Author: Andrey Gitin
Affiliation: Max Born Institute of Nonlinear Optics and Superfast Spectroscopy, Berlin, Germany; E-Mail: agitin@mbi-berlin.de
Abstract: For many experiments it is necessary to increase the energy of ultrashort pulses (USPs). However, if intensity of UPS overcomes the level Io, the optical Kerr effect destroys the active body of ultrafast pulse amplification. Using the chirp pulse amplifier technique [1], the damage of an active (gain) medium can be avoided. According to this technique, the duration of the input transform limited USP is stretched in time (`chirped') by means of a grating dispersion delay line with the positive group velocity dispersion, which is called a stretcher. Thus, the peak intensity of the pulse is reduced to a level Io and it does not destruct the gain medium. Then, the energy of this pulse is amplified in the amplifier active (gain) medium. After the amplification its initial duration is restored with the help of a grating dispersion delay line with the negative dispersion, which is called compressor. Grating dispersion delay lines are now widely used in chirped-pulse amplification technique as the compressor and the stretcher. According to a first-principles method, the fundamental theory of these delay lines must be based on first principles of optics. Note that the correct definition of the time delay between input and output wave-fronts of a delay line is possible only when the system satisfies the tautochronism principle, i.e. the time delay between the wave-fronts is the same for all rays. Although a diffraction grating does not satisfy the tautochronism principle, but a pair of diffraction gratings can be combined so that the input and the output wave-fronts of the system still satisfy the principle [2]. There are only two such grating delay lines: Treacy’s compressor [3] and Martinez’s stretcher [4]. According to the unfolding technique, the dispersion of the compressor and the stretcher and can be characterized by the "zero-distant pulse fronts"[5,6]. As the ‘‘zero-distance phase front” characterizes aberrations of an optical system, it is easy to see how the "zero-distant pulse front" of the stretcher depends on aberrations of its optical system [7].

Type of Paper: Article
Title: Pulse Compression of Ultrashort UV Pulses by Self-Phase Modulation in Bulk Material
Authors: N. Krebs, I. Pugliesi and E. Riedle
Affiliation: Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians-Universität (LMU), Oettingenstraße 67, 80538 München, Germany; E-Mail: riedle@physik.lmu.de
Abstract: We show that self-phase modulation of UV pulses in bulk materials leads to a large spectral broadening and allows for a significant reduction of the pulse duration. It represents a compact addition to an existing optical setup without major losses in pulse energy. We find that for pulse intensities in the range of a few µJ a thin crystal is favorable due to the strong dispersion in the UV and the limitations set by self-focusing. Furthermore, in contrast to spectral broadening in gaseous media, the self-focus has to lie outside the crystal to avoid beam break up. In the experiment we focus UV pulses into a 1 mm-thick CaF2 crystal. For long input pulses a shortening factor up to 2.4 is achieved: the 120 fs long third harmonic output of Ti:sapphire amplifier is compressed down to 50 fs. For a central wavelength of 315 nm we generate pulses as short as 14.9 fs after compression with an UV pulse shaper. Both regimes render the technique a promising addon for convenient pulse shortening in the UV.

Type of Paper: Article
Title: Linear Electro Optic Effect for High Repetition Rate Carrier Envelope Phase Control of Ultra Short Laser Pulses
Authors: O. Gobert ¹, D. Rovera ², G. Mennerat ¹ and M. Comte ¹
Affiliation: ¹ CEA-Saclay, IRAMIS, Service des Photons, Atomes et Molécules, 91191 Gif-sur-Yvette, France; E-Mail: michel.comte@cea.fr
² LNE-SYRTE, Observatoire de Paris - LNE - CNRS - UPMC, 61 avenue de l'Observatoire, 75014 Paris, France
Abstract: Carrier Envelope Phase (CEP) control of ultrashort laser pulses is of fundamental importance in a number of applications in Physics. This subject has been studied intensively for more than ten years and original techniques were recently proposed and experimentally demonstrated. The most promising of these are mainly based on the transverse acousto-optic effect, on the linear electro-optic (EO) effect or rely on longitudinal acousto-optic modulator. Depending on the specific case and the physical effect they rely on, they can apply to amplified laser pulses or be used to control the pulse train inside the cavity of a mode-locked oscillator. Solutions based on the transverse acousto-optic effect or the linear EO effect allow the fastest CEP corrections (with the exception of the passive “all optical” method relying on Difference Frequency Generation or Optical Parametric Amplification). This paper is devoted to analyse the principle and applications of the linear EO effect for the control of the CEP. We first review in detail how a CEP shift can be generated with an EO crystal, this shift being linked to the static electric field dependence of the difference between the group and the phase delay induced in the crystal. After reviewing the best results obtained to date, we will introduce another original method, still based on the use of the EO effect in a more complex optical scheme.
Variation on the theme of group and phase delay control will be discussed, as well as a new technique which allows a fast and accurate determination of the EO coefficients and their dispersion. As a conclusion, we will present the main parameters of some crystals for their use in a CEP modulation or stabilization system.

Type of Paper: Article
Title: Can the HOMO-LUMO Gap of Atoms and Molecules Be Controlled by Ultrafast Laser Pulses?
Authors: R. Ramakrishnan and M. Nest
Affiliation: Theor. Chemie, TU Muenchen, Lichtenbergstr 4, 85747 Garching, Germany; E-Mail: mathias.nest@mytum.de
Abstract: The HOMO-LUMO gap of a material determines many of its physical and chemical properties, like conductivity, optical response, and the ability to act as an oxidizing or reducing agent. Here, we study the control of the HOMO-LUMO gap (or the two levels separately), using ultrafast and strong laser pulses. As test systems we employ molecules which are suitable for molecular electronics, and small metal clusters.

Type of Paper: Article
Title: Production of Sub-hundred Femtosecond Electron Pulses for Coherent THz Radiation Source
Authors: H. Hama et al.
Affiliation: Electron Light Science Centre, Tohoku University, 1-2-1 Mikamine, Taihaku-ku, Sendai 982-0826, Japan; E-Mail: hama@lns.tohoku.ac.jp
Abstract: Considerations for the production of sub-hundred femtosecond electron bunches from a typical thermionic rf gun injector system which consists of an alpha (a-)magnet and a traveling wave accelerating structure are thoroughly discussed. It is found that the space charge effects overrule the beam dynamics seriously in such low energy injector. Therefore, velocity bunching in linac plays a decisive role in bunch compression towards sub-hundred femtosecond range. We demonstrate that thermionic rf gun possesses an advantage of velocity bunching and the compressed bunches with bunch length of ~ 50 fs can be attained in a wide range of operation conditions, which is very attractive to produce coherent synchrotron radiation in THz frequency region. The effectiveness of compressed bunch under this strategy will be shown.

Type of Paper: Article
Title: Few-Cycle, Phase-Stable Intense Infrared OPCPA System and Its Applications to High-Harmonic Generation in the Soft X-ray Region
Author: Nobuhisa Ishii
Affiliation: Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581, Japan; E-Mail: ishii@issp.u-tokyo.ac.jp
Abstract: We describe the details of an BIBO-based optical parametric chirped-pulse amplifier, which is capable of delivering sub-two-cycle, carrier-envelope-phase (CEP) stabilized, mJ-class laser pulses around 1500 nm with a repetition rate of 1 kHz. We examine the production of CEP-stabilized infrared seed pulses based on difference frequency generation. We explain the unique property of degenerate optical parametric amplification (OPA) using BIBO and a Ti:sapphire laser as a pump. As preliminary results, we demonstrate the application of the infrared source to CEP-dependent high harmonic generation in the soft x-ray region of the spectrum including the water window.

Type of Paper: Review
Title: Free Electron Laser for Hard X-Ray Region: An Overview of the Used Schemes
Authors: Sandeep Kumar ¹, Heung-Sik Kang ¹, Dong-Eon Kim ²
Affiliations: ¹ Pohang Accelerator Laboratory, San 31, Hyoja-dong, Pohang, Kyungbuk, Korea
² Department of Physics, Center for Attosecond Science and Technology (CASTECH), Max Planck Center for Attosecond Science, Pohang University of Science and Technology (POTECH), San 31, Hyoja-dong, Pohang, Kyungbuk, 790-784, Korea; E-Mail: kimd@postech.ac.kr
Abstract: To study the electron dynamics in atoms, molecules and nanoscopic systems, we need a new tool with attosecond temporal and nanometer spatial resolutions. The generation of an isolated attosecond hard x-ray pulse at different photon energies and with a higher photon-flux becomes necessary for such state-of art advanced tools. We review several schemes of soft x-ray and hard x-ray generation using free electron laser (FEL). Self-amplified spontaneous emissions (SASE) scheme, the high gain harmonic generation (HGHG) and various enhancement schemes through seeding and beam manipulations are discussed especially in view of the generation of attosecond x-ray pulses. We also discuss our recent work on the generation of attosecond hard x-ray pulses using PAL-XFEL parameters. We employ enhanced SASE scheme combined with PAL XFEL. We optimize laser, chicane, and electron-beam parameters to generate an isolated attosecond hard x-ray pulse. We demonstrate in simulation that the manipulation of electron-energy beam profile may lead to the generation of an isolated attosecond hard x-ray. Using the parameters of the 10 GeV electron beam of the PAL XFEL, we show that an isolated 150 attosecond pulse at 0.1 nm can be generated.

Type of Paper: Review
Title: Short Pulse Thin-Disk Lasers and Their Power Scaling for Pumping the Few-Cycle-OPCPA Systems in ELI-Beamlines
Author: Thomas Metzger
Affiliation: Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 GARCHING, Germany; E-Mail: thomas.metzger@mpq.mpg.de
Abstract: The European Extreme Light Infrastructure Project (ELI), ELI-Beamlines in Prague, has been started up with the aim among others to develop infrared few-cycle optical parametric chirped pulse amplifiers (OPCPA) at high repetition rates in the kilohertz and pulse peak powers in the petawatt regime. Short-pulse-pumped optical parametric amplification has proven to be a powerful method to realize few-cycle coherent light pulses but requires high average power picosecond laser sources especially tailored for pumping OPCPAs. We report on the current thin-disk laser development at the MPQ, the scaling technology, the synchronization between pump and seed sources and first OPA results.

Type of Paper: Article
Title: Laser-Plasma Acceleration with FLAME and ILIL Ultraintense Lasers
Author: Leo Gizzi ^1,2 et al.
Affiliation: ¹ ILIL, Istituto Nazionale di Ottica, UOS “Adriano Gozzini,” CNR, Via G. Moruzzi 1, Pisa, Italy; E-Mail: la.gizzi@ino.it
² INFN, Italy
Abstract: We report on the development of radiation and electron sources based on laser plasma acceleration for biomedical and nuclear applications, based on the use of both table top TW laser at ILIL and the 250TW FLAME laser system at LNF. We use the ILIL laser to produce wakefield electrons in a self-focusing dominated regime in a mm scale gas-jet to generate large, uniform beams of MeV electrons for electron radiography and radiobiology tests. This acceleration regime is described in detail and key parameters are given to establish reproducible and reliable operation of this source. We then use the Flame laser to drive laser-plasma acceleration in a cm-scale gas target to obtain stable production of 100 MeV range electrons to drive a inverse Compton scattering gamma ray source. The configuration is discussed in view of the optimization of this all-optical gamma-ray source for nuclear applications.

Type of Paper: Review
Title: Direct Electron Acceleration in Radially Polarized Laser Beams
Authors: Charles Varin ¹, S. Payeur ², V. Marceau ³, J.-C. Kieffer ², F. Légaré ², M. Piché ³ et al.
Affiliation: ¹ University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
² INRS Energie et Matériaux, Université du Québec, Varennes, Québec, J3X-1S2, Canada
³ Centre d'optique, photonique et laser, Université Laval, Québec, Québec, G1V 0A6, Canada; E-Mail: cvarin@uottawa.ca
Abstract: In the past years, there has been a growing interest in innovative applications of radially polarized laser beams. Among them, the particular field of laser-driven electron acceleration has received much attention. Recent developments in high-power infrared laser sources at the Advanced Laser Light Source (Varennes, Qc, Canada) allowed the experimental observation of quasi-monochromatic 23 keV electron beams produced by tightly focused radially polarized laser pulses. Theoretical analyses suggest that the production of collimated attosecond electron pulses is within reach of the actual technology. Such an ultrashort electron pulse source would be a unique tool for fundamental and applied research. In this paper, we propose an overview of this emerging topic and expose some of the challenges to meet in the future.

Type of Paper: Review
Title: Ultrashort Dissipative Solitons in Mode-Loked Fiber Lasers
Authors: Sofia C. V. Latas and Mário F. S. Ferreira
Affiliation: I3N-Institute of Nanostructures, Nanomodelling and Nanofabrication, Department of Physics, University of Aveiro, 3810-193 Aveiro, Portugal;
E-Mail: mfernando@ua.pt (M.F.S.F.)
Abstract: We investigate numerically, both in time and frequency domains, the characteristics of different types of ultrashort pulsating and chaotic solitons generated by mode-locked fiber lasers, whose operation is described using the complex Ginzburg-Landau equation. The influence of some higher-order effects, namely the third-order dispersion, intrapulse Raman scattering, and self-steepening, on the dynamics of such ulrashort pulses is also investigated. We show that these higher-order effects can have a dramatic impact and that, for some ranges of the parameter values, fixed-shape solitons can be achieved.

Type of Paper: Review
Title: High Spatio-temporal Quality Petawatt-Class Ultra-Intense Laser System and Applications
Authors: H. Kiriyama, T. Shimomura, M. Mori, Y. Nakai, M. Tanoue, K. Kondo, S. Kanazawa, A. S. Pirozhkov, H. Hayashi, K. Ogura, H. Kotaki, H. Okada, A. Kosuge, Y. Fukuda, M. Nishiuchi, M. Kando, S. V. Bulanov, K. Nagashima, M. Yamagiwa, K. Kondo, A. Sugiyama and P. R. Bolton
Affiliation: Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0216, Japan; E-Mail: kiriyama.hiromitsu@jaea.go.jp
Abstract: This paper reviews techniques for improving the temporal contrast and spatial beam quality in an ultra-intense laser system that is based on chirped-pulse amplification (CPA). We describe the design, performance, and characterization of our laser system, which has the potential for achieving a peak power of 600 TW. We also describe applications of this laser system in the relativistic dominated regime of laser-matter interactions and discuss a compact, high efficiency diode-pumped laser system.

Type of Paper: Article
Title: Single-Grating Monochromators for Extreme-Ultraviolet Ultrashort Pulses
Authors: Luca Poletto and Fabio Frassetto
Affiliation: National Council for Research of Italy, Institute of Photonics and Nanotechnologies; E-Mail: poletto@dei.unipd.it
Abstract: A single-grating monochromator can be adopted for ultrashort pulses without altering in a significant way the pulse duration, provided that the number of illuminated grooves is equal to the resolution. Two configurations for single-grating time-preserving monochromators are compared: the classical-diffraction mount (CDM) and the off-plane mount (OPM). The advantages and drawbacks of both configurations are presented. The two geometries can be joined in a new and innovative design of a monochromator with two interchangeable diffracting stages both used at grazing incidence, one with the gratings in the CDM and the other in the OPM. The use of two stages gives great flexibility: the OPM stage is used for sub-50 fs time response and low spectral resolution, the CDM stage for 100-300 fs time response and high spectral resolution. The design overcomes the limits of the two single configurations, giving on the same instrument either ultrafast time response with low spectral resolution or longer time response with higher resolution.

Type of Paper: Article
Title: Adaptive Generation and Diagnostics of Linear Few-Cycle Light Bullets
Authors: M. Bock and R. Grunwald
Affiliation: Max Born Institute for Nonlinear Optics and Short-Pulse Spectroscopy; E-Mail: grunwald@mbi-berlin.de
Abstract: Recently we introduced the class of highly localized wavepackets (HLWs) as a generalization of optical Bessel-like needle beams. Here we report on the progress in this field. In contrast to pulsed Bessel beams and Airy beams, HLW-type ultrashort-pulsed wave phenomena propagate with high stability in both spatial and temporal domain, are nearly paraxial (supercollimated), have fringe-less spatial profiles and thus represent the best possible approximation to linear "light bullets". Like Bessel beams and Airy beams, HLWs behave self-reconstructing. Adaptive HLWs can be shaped by ultraflat three-dimensional phase profiles (generalized axicons) which are programmed via calibrated grayscale maps of liquid-crystal-on-silicon spatial light modulators. Light bullets of even high complexity can either be freely formed from quasi-continuous phase maps or discretely composed from addressable arrays of identical nondiffracting beams. The characterization of few-cycle light bullets requires spatially resolved measuring techniques. In our experiments, wavefront, pulse and phase were detected with a Shack-Hartmann wavefront sensor, 2D-autocorrelation and spectral phase interferometry for direct electric-field reconstruction (SPIDER). The combination of the unique propagation properties of light bullets with the flexibility of adaptive optics opens new prospects for applications of structured light like optical tweezers, microscopy, data transfer and storage, laser fusion, plasmon control or nonlinear spectroscopy.