Showing papers on "Chirped pulse amplification published in 1999"

Petawatt laser pulses.

Abstract: We have developed a hybrid Ti:sapphire–Nd:glass laser system that produces more than 1500??TW (1.5??PW) of peak power. The system produces 660??J of power in a compressed 440±20 fs pulse by use of 94-cm master diffraction gratings. Focusing to an irradiance of >7×1020 W/cm2 is achieved by use of a Cassegrainian focusing system employing a plasma mirror.

Single-shot real-time characterization of chirped-pulse amplification systems by spectral phase interferometry for direct electric-field reconstruction

Abstract: We characterize chirped-pulse amplification systems by using spectral phase interferometry for direct electric-field reconstruction. For the first time to the authors’ knowledge, single-shot real-time operation has been obtained for this technique, leading to a fast and accurate optimization of these systems.

Evaluation of an ultrabroadband high-gain amplification technique for chirped pulse amplification facilities

Abstract: Recently, an amplification technique for ultrashort pulses was explored in detail in a theoretical paper by Ross et al. [Opt. Commun. 144, 125 (1997)]. The technique, based on nonlinear optics, is called optical parametric chirped pulse amplification. It has a number of features that, in principle, make it highly attractive. It primarily offers extremely large gains simultaneously with extremely large bandwidths. Additional attractions are virtually no spatial and temporal phase distortion of the amplified pulse, high efficiencies and a low thermal loading, reduced amplified spontaneous emission levels, small optical material lengths, and an inherent simplicity of implementation. We present an evaluation of the technique as a front end amplifier for the ultrashort pulse amplification chain of the Vulcan laser system. Such a device could replace some of the existing amplification in Nd:glass and additionally have a wider effect as a direct replacement of Ti:sapphire regenerative amplifiers on large-scale chirped pulse amplification scale facilities.

Diagnosing hot electron production by short pulse, high intensity lasers using photonuclear reactions

Abstract: Solid targets irradiated with 1019 W/cm2 or greater of 1 μm light in picosecond pulses are found to be radioactive. The strongest activities observed are the result of photonuclear reactions in which an energetic photon excites the nucleus sufficiently to produce particle emission leaving a radioactive daughter. The photoreaction cross sections are known for a wide range of nuclei and provide a quantitative measure of the photon flux produced in the target. Both the delayed daughter activities and measurements of the prompt particles emitted in the reaction can be used as diagnostics. Examples of these techniques applied in diagnosing experiments at the Nova laser facility adapted to generate petawatt pulses using chirped pulse amplification will be presented. These results will be compared with bremsstrahlung photon spectra calculated using electron spectra measured in a magnetic spectrograph.

Short pulsed laser machining: How short is short enough?

Abstract: Machined feature quality is examined, and the effects of laser pulse width (and thus peak power or intensity) are investigated for the following four laser systems: (1) a millisecond-class, free-running Nd:YAG; (2) a 100-nanosecond-class, Q-switched Nd:YAG laser; (3) a 100-picosecond-class, mode locked Nd:YAG laser; and (4) a 100-femtosecond-class, Ti:sapphire chirped pulse amplification laser. The effect of shorter laser wavelength is also examined by using the second harmonic wavelength of the Nd:YAG laser in the Q-switched and the mode locked pulse formats. Hole drilling and cutting of superalloy, ceramic, and composite materials are studied. The machined feature quality is improved as the pulse width becomes shorter and the peak intensity becomes higher. The shorter wavelength provides another significant improvement. Finally, an attempt is made to view these quality improvements in the context of process throughput and cost of ownership.

Influence of optical quality on chirped-pulse amplification: characterization of a 150-nm-bandwidth stretcher

Abstract: We use a spectral interferometric method to characterize a 150-nm-bandwidth stretcher. We analyze the phase distortion that is due to the system and show the influence of the quality of the mirrors on the pulse duration.

Low-noise amplification of high-power pulses in multimode fibers

Abstract: Low-noise amplification of high-power pulses in multimode erbium/ytterbium-doped fibers is demonstrated. The use of multimode fiber amplifiers allows to overcome the peak power limitations of single-mode amplifiers. As a result femtosecond pulses can be efficiently amplified to peak powers >50 kW in a high-power chirped pulse amplification system using chirped PPLN for frequency-doubling. With an average power level of 1.2 W at the fundamental wavelength of 1.55-/spl mu/m average powers up to 420 mW are generated at 775 mm.

Generation of a broad amplified spectrum in a femtosecond terawatt Ti:sapphire laser by a long-wavelength injection method

Abstract: A long-wavelength injection method is proposed that will yield a broad amplified spectrum in a femtosecond terawatt Ti:sapphire laser. By injecting a seed pulse on the red side of the gain peak and amplifying it to a saturated fluence level, we could significantly compensate for the spectral narrowing that is due to the gain-narrowing effect by use of the amplifying characteristics of a positively chirped pulse in a gain-saturated regime, and 20-fs, 3-TW pulses could be demonstrated from a Ti:sapphire laser with two multipass amplifiers.

LULI 100-TW Ti:sapphire/Nd:glass laser: a first step toward a high-performance petawatt facility

Abstract: We have implemented a Ti:sapphire/mixed Nd:glass laser syste at LULI producing sub-picosecond pulses in the 100 TW power range. Focusing to a 1.5-times diffraction-limited spot results in a peak intensity on target over 10 19 W/cm 2 . Significant experiments in particle acceleration, X-ray laser and other basic plasma physics researchers have been carried out since this implementation. This paper details the characteristics of the present set-up and the main path of progress towards a high performance petawatt facility.

Kilohertz gain-switched laser operation and femtosecond regenerative amplification in Cr:forsterite

Abstract: We present a comprehensive study of the optimum operating regime in a gain-switched Cr:forsterite laser at a repetition frequency of 1 kHz with special attention to temperature-dependent and parasitic absorption effects and proper resonator design. On the basis of the results achieved, me demonstrate highly efficient (13% extraction efficiency) operation of a femtosecond regenerative amplifier based on Cr:forsterite and operating near room temperature with a novel BBO Pockels cell that is highly resistant to optical damage. Chirped pulse amplification raises the pulse energy to 355 /spl mu/J in /spl ap/30 cavity round trips which corresponds to an amplification factor of /spl ap/5.5/spl times/10/sup 5/. The nearly transform limited 200-/spl mu/J 135-fs compressed pulses near 1.25 /spl mu/m have a peak power of /spl ap/1.5 GW. Frequency doubling with 52% conversion efficiency in LBO produces femtosecond pulses of 104-/spl mu/J energy in the visible near 625 nm.

Laser system for a high duty cycle photoinjector

Abstract: We have developed a solid-state laser system that produces a 1 MHz pulse train of 800 equal amplitude pulses with 25 μJ per pulse at λ=1054 nm ; the repetition rate is 1 Hz. The laser pulse train is produced by a mode-locked Nd:YLF oscillator, synchronized to the phase of the photoinjector RF. The pulses are amplified in a Nd : glass multipass amplifier followed by a two-pass amplifier. The laser system uses chirped pulse amplification to produce 2 ps pulses. After two stages of second harmonic generation to λ=263 nm and transport losses, 5 μJ per pulse of UV are available at the Cs2Te photocathode of the RF gun. The photocathode quantum efficiency is in the 2–6% range, and electron bunches with charge in excess of 10 nC have been extracted during photoinjector operation.

Femtosecond interferometric autocorrelations in the presence of pulse-front distortions

Abstract: The tilt of the pulse front caused by misalignment in stretcher-compressor devices which are used in chirped pulseamplification should be carefully considered in the design of femtosecond laser systems. We present a convenientprocedure for online measurement and minimization of the tilt in a grating stretcher/compressor setup. In addition,we present a theoretical model for the autocorrelation signal in the presence of pulse front distortion. The influence of the pulse front tilt to the autocorrelation function is numerically simulated and compared with the case for pulses with fourth order chirp.Keywords: femtosecond pulse, interferometric autocorrelation, pulse front distortion, chirp 1. INTRODUCTION The tilt of the pulse front is one of the major issues in chirped pulse amplification (CPA) systems.'3 Pulse front distortion can also occur when femtosecond pulses are focused4'5 or passed through birefringent crystals.6 It leads toan undesired increase of the effective pulse duration and is accompanied by spatial chirp. Further, it can substantiallyreduce the accuracy of interferometrically measured optical nonlinearities.7 Even the overlap of femtosecond pulses

'Progress-P' laser facility with chirped-pulse amplification in neodymium glass

Abstract: A Nd:YLF/Nd:glass laser facility with chirped-pulse amplification capable of generating pulses with a duration of 1.5 ps and a power up to 30 TW at the wavelength of 1053 nm was investigated. The facility consists of a initial laser system, producing a chirped pulse with an energy up to ~1 J, a main three-stage rod amplifying channel with a 85-mm aperture of the output stage, a pulse compressor based on 210 mm × 420 mm diffraction gratings, and a focusing axial parabolic mirror (with an aperture ratio of 1:11). Optimisation of the parameters of the laser facility allowed us to generate an output laser beam with an angular divergence close to the diffraction limit and an intensity up to ~1019 W cm-2 . Laser radiation with such parameters can be employed in experiments on the interaction of superstrong laser fields with matter.

High-repetition rate 1-J green laser system.

Abstract: A laser-diode-pumped high-repetition-rate zigzag slab Nd:YAG oscillator-amplifier system is developed as the pumping source of a high-average-power and terawatt Ti:sapphire chirped pulse amplification laser system. This system can produce a greater than 2-J high-energy fundamental laser pulse at a repetition rate of 100 Hz. The frequency-doubled energy with a diffusion-bonded KTP crystal is 1 J at a repetition rate of 100 Hz.

Suppression of amplified spontaneous emission in a femtosecond chirped-pulse amplifier

Abstract: The suppression of amplified spontaneous emission (ASE) that arises during the femtosecond chirped-pulse amplification is presented. On the basis of the distinct differences in the spatial, temporal and spectral region between ASE and the amplified laser signal, the noise arising from ASE was effectively filtered out. The ratio between the amplified femtosecond pulse and the ASE peak power was higher than 10 7 . Pulses as short as 38 fs were amplified to peak power of 1.4 TW.

Study on Design of 10TW Class 10fs Ti: sapphire Laser

Abstract: In this paper, we report the design considerations for a 10 TW, 10 fs class Ti: sapphire chirped-pulse amplification system and technically describe a gain narrowing compensator, a pulse stretcher and compressor with a wide spectral range, and high-energy mirrors also with a wide spectral range. These devices are key optical components for generating 10 TW, 10 fs class laser pulses.

Pulsed x-ray laser amplifier

Abstract: Two techniques for producing plasma x-ray laser amplifiers, encompassing laser generated high density, micron-sized plasma columns, and microwave driven low density, large plasma volumes which provide the population inversions necessary for x-ray lasing to occur in the plasmas. The laser driven plasma is created by short-pulse, high power laser beams produced by chirped pulse amplification techniques, which are confined to micron-sized cylindrical channels by self-focusing effects and electron density conditioning means. The extremely high powers provide for complete stripping of medium to high Z atoms, which allows for recombination cascading to produce population inversions on the higher energy x-ray transition levels. The very short plasma creation times allow a laser produced "seed" x-ray pulse to be properly timed for injection into the plasma when population inversions reach maximum levels. The microwave driven low density plasma laser produces the population inversion required for laser amplification by use of cyclotron resonance heating of electrons, which affects the fractional ionization and the electron induced de-excitation processes responsible for output power determination. Due to the ability to create large volume plasmas and rapidly change the electron temperature, optimal power levels are achieved. This type of laser may also operate in other, longer wavelength regions of the electromagnetic spectrum.

Pseudo phase matching parametric chirped pulse amplification system

Abstract: PROBLEM TO BE SOLVED: To provide a compact amplifier of a high energy and super short light pulse. SOLUTION: This system is achieved by a light pulse amplification and emission system consisting of a pump light source 100 which generates a light pump pulse having a preliminarily dertermined wide, a signal light source 130 generating a light signal pulse, a combining optical system 160 which receives the light pump pulse and the light signal pulse to combine them and is for supply the combined light pulses, a parametric amplifier 170 which is consisting of a quasi-phase-matched crystal amplifying the light signal pulse by using the energy of the light pump pulse while receiving the combined light pulses and an application unit which receives the amplified output of the amplifier and applies it to a clearly expressed position. Preferably, this system is composed of a chirped pulse amplification and emission system consisting of the light pulse amplification and emission system and a compressor 180 which receives the light signal pulse amplified in the parametric amplifier and compresses it. COPYRIGHT: (C)2000,JPO

Effect of self-phase modulation in chirped-pulse-amplification-like schemes

Abstract: A detailed analytical investigation is made of the effect of nonlinear self-phase modulation in chirped-pulse-amplification-like schemes. It is demonstrated that self-phase modulation in the amplifier between the stretcher and the compressor breaks the dispersive sign symmetry of the configuration. This implies that, although self-phase modulation is usually considered a deleterious effect, different situations are possible, depending on the parameter regimes considered. In particular, the influence of self-phase modulation on the low-intensity wings of the compressed pulse may be more or less deleterious, depending on the dispersive sign combination of the stretcher and the compressor; in certain parameter regimes, it may in fact even enhance the pulse compression.

Single-shot real-time characterization using spectral phase interferometry for direct electric-field reconstruction

Abstract: Summary form only given. Ultra-short optical pulses have set huge problems of characterization because their duration is far below the response time of all the electronic detectors. Various methods have been demonstrated. Recently, spectral shearing interferometry was implemented as spectral phase interferometry for direct electric-field reconstruction (SPIDER). This method bears many advantages, like easy single-shot implementation because the measured spectrum contains all the information on the spectral phase of the fundamental pulse, algebraic inversion from the experimental trace to the spectral phase to characterize. (i.e. non-iterative, and thus fast and accurate as long as the experimental trace is accurate). These advantages, which are of prior interest for the characterization and optimization of femtosecond sources, have not been clearly demonstrated up to now. We present results on the single-shot, real-time characterization of a laser chirped pulse amplification system using SPIDER.

Chirp compensation in a femtosecond direct space-to-time optical pulse shaper

Abstract: Summary form only given. We report the first demonstration of dispersion control using the direct space-to-time (DST) pulse shaper. It is well known that dispersion can be controlled in the FT pulse shaper by varying the longitudinal position of one of the gratings; this is the basis of the pulse stretcher commonly used for chirped pulse amplification. As we show a different recipe is needed for dispersion control in the DST shaper.

Multiterawatt laser-linac facility

Abstract: Summary form only given. Recent progress in the generation and amplification of femtosecond pulses has made it possible to achieve peak powers of the order of tens of terawatts with relatively modest laser energy (<10 J). As a result, compact, multiterawatt lasers can be built at modest expense. Such lasers are of great interest for relativistic laser-plasma interaction research, for production of ultrafast X-rays, hard X-rays and /spl gamma/-rays for radiography, and for advanced electron acceleration research. We are currently developing a Ti:sapphire chirped pulse amplification laser, called Falcon. This laser is being constructed near the LLNL 100 MeV electron linear accelerator and, ultimately, is synchronized with this linac with sub-picosecond temporal accuracy, Such a facility permits a range of advanced experiments in which intense laser pulses interact with high peak current bunches of relativistic electrons. To achieve this synchronization part of the Falcon laser pulse is used to produce the electron beam in a photoinjector electron gun which injects electrons into the main accelerator. Furthermore, the RF of the S-band linac is slaved to the laser oscillator.

Fiber lasers in ultrafast optics

Abstract: The current status of ultrafast fiber lasers is discussed. Recent advances in optical fiber designs as well as improved saturable absorbers have greatly improved the performance and the reliability of ultrafast fiber oscillators. Equally significant have been improvements in ultrafast fiber amplifier designs and compact chirped pulse amplification systems in conjunction with chirped periodically-poled LiNbO 3 , which now allow the manufacture of compact ultrafast fiber laser systems that can exceed the performance of conventional ultrafast lasers based on bulk optics. The unique size advantage of fiber lasers opens up the field of ultrafast optics to novel OEM-type applications. For example ultrafast fiber lasers have been successfully employed as subsystems in all-optical time delay scanning, for two-photon microscopy as well as for THz pulse generation.

Focused intensities of 1020 Wcm-2 with the upgraded Vulcan CPA interaction facility

Abstract: There has been considerable interest in the last 10 years in the physics of ultra-high power laser interactions. With all high power lasers such as Vulcan there is a limit to the energy that can be extracted from laser amplifiers at short pulse-lengths due to the intensity dependent non-linear refractive index. The technique of Chirped Pulse Amplification has overcome the classic limit and has resulted in massive increases in focused intensity. The large increase in on target intensity is achieved by a substantial, usually orders of magnitude, reduction in pulse duration while at the same time maintaining comparable pulse energy and focusability.