Showing papers on "Chirped pulse amplification published in 2009"

Generation of sub-three-cycle, 16 TW light pulses by using noncollinear optical parametric chirped-pulse amplification

Abstract: We present a two-stage noncollinear optical parametric chirped-pulse amplification system that generates 7.9 fs pulses containing 130 mJ of energy at an 805 nm central wavelength and 10 Hz repetition rate. These 16 TW light pulses are compressed to within 5% of their Fourier limit and are carefully characterized by the use of home-built pulse diagnostics. The contrast ratio before the main pulse has been measured as 10(-4), 10(-8), and 10(-11) at t=-3.3 ps, t=-5 ps, and t=-30 ps, respectively. This source allows for experiments in a regime of relativistic light-matter interactions and attosecond science.

High-repetition-rate chirped-pulse-amplification thin-disk laser system with joule-level pulse energy

Abstract: We are reporting on the development of a diode-pumped chirped-pulse-amplification (CPA) laser system based on Yb:YAG thin-disk technology with a repetition rate of 100 Hz and output pulse energy in the joule range. The focus lies with the first results of the preamplifier--a regenerative amplifier (RA) and a multipass amplifier (MP). The system consists of a front end including the CPA stretcher followed by an amplifier chain based on Yb:YAG thin-disk amplifiers and the CPA compressor. It is developed in the frame of our x-ray laser (XRL) program and fulfills all requirements for pumping a plasma-based XRL in grazing incidence pumping geometry. Of course it can also be used for other interesting applications. With the RA pulse energies of more than 165 mJ can be realized. At a repetition rate of 100 Hz a stability of 0.8% (1σ) over a period of more than 45 min has been measured. The optical-to-optical efficiency is 14%. The following MP amplifier can increase the pulse energy to more than 300 mJ. A nearly bandwidth-limited recompression to less than 2 ps could be demonstrated.

Mid-IR short-pulse OPCPA with micro-Joule energy at 100kHz

Abstract: We present a novel mid-IR source based on optical parametric chirped pulse amplification (OPCPA) generating 96 fs pulses (9.0 cycles) at 3.2 μm with an energy of 1.2 μJ, at a repetition rate of 100 kHz. The amplified spectrum supports a minimum Fourier transform limited pulse duration of 45 fs, or 4.2 cycles. Our use of OPCPA allows the direct amplification of few-cycle pulses at this mid-IR wavelength, and is inherently scalable to higher energies. The seed source for the system is based on difference frequency generation (DFG) between two outputs of the same fibre laser: this source is expected to be intrinsically CEP stable.

High-order harmonic generation at a megahertz-level repetition rate directly driven by an ytterbium-doped-fiber chirped-pulse amplification system

Abstract: We report the first experimental demonstration (to our knowledge) of high-order harmonic generation in rare gases driven by a state-of-the-art high-power Yb-doped-fiber chirped-pulse amplification system. The fiber laser delivers 270 fs pulses in the 30-100 μJ energy range at repetition rates varying from 100 kHz to 1 MHz. A proper focalization allows reaching several 1013 W/cm2 in a gas jet. We have been able to produce and detect harmonics up to order 31 (33.2 nm) in Ar at a 100 kHz repetition rate. High-order harmonic generation at 1 MHz is also demonstrated in Xe up to harmonic 15. The demonstrated extreme UV (XUV) source will bring ultrashort XUV coincidence experiments from synchrotron facilities to tabletop laboratories.

Self-compression of millijoule 1.5 microm pulses.

Abstract: We demonstrate a four-stage optical parametric chirped-pulse amplification system that delivers carrier-envelope phase-stable approximately 1.5 microm pulses with energies up to 12.5 mJ before recompression. The system is based on a fusion of femtosecond diode-pumped solid-state Yb technology and a picosecond 100 mJ Nd:YAG pump laser. Pulses with 62 nm bandwidth are recompressed to a 74.4 fs duration close to the transform limit. To show the way toward a terawatt-peak-power single-cycle IR source, we demonstrate self-compression of 2.2 mJ pulses down to 19.8 fs duration in a single filament in argon with a 1.5 mJ output energy and 66% energy throughput.

Frontend light source for short-pulse pumped OPCPA system

Abstract: We present the development of a light source for generating optically synchronized seed pulses both for the parametric amplifier chain and the pump-laser chain of the Petawatt Field Synthesizer (PFS), which is currently under construction at MPQ. The PFS system aims at delivering waveform-controlled few-cycle laser pulses with PW-scale peak power using optical parametric chirped pulse amplification (OPCPA). Methods of generating the broadband near-infrared (NIR) seed pulses for the OPCPA chain by spectral broadening using few-cycle pulses are presented. We also demonstrate the generation of a supercontinuum spanning up to three octaves (270–1500 nm) using cascaded hollow-core fibers which supports sub-cycle pulse duration.

High energy ultrashort pulses via hollow fiber compression of a fiber chirped pulse amplification system

Abstract: A simple, robust and compact pulse compressor for high-repetition rate high-peak power fiber chirped pulse amplification systems is presented. We use noble-gas-filled hollow fibers for spectral broadening of the optical pulses via self-phase modulation. Subsequent compression with chirped mirrors shortens the pulses by more than a factor 10. Pulses shorter than 70 fs with pulse energies of the order of 100μJ have been obtained resulting in a peak power up to 1 GW at 30.3 kHz. Additionally, nonlinear polarization rotation has been used for temporal pulse cleaning during the nonlinear compression at 30.3 kHz and 100 kHz, respectively.

Femtosecond Yb-fiber chirped-pulse-amplification system based on chirped-volume Bragg gratings

Abstract: A 100 W amplified (75 W compressed) femtosecond (650 fs) Yb-fiber chirped-pulse-amplification system is demonstrated using broadband chirped-volume Bragg gratings (CVBGs) for the stretcher and compressor. With a 75% compression efficiency, the CVBG-based compressor exhibits an excellent average power handling capability and indicates the potential for further power scaling with this compact and robust technology.

Adaptive acousto-optic technique for femtosecond laser pulse shaping

Abstract: We discuss the theoretical and experimental investigation of acousto-optic dispersive tunable filters, based on quasi-collinear geometry of light-sound interaction in a tellurium dioxide single crystal. The geometry uses the effect of strong acoustic anisotropy in the paratellurite as well as peculiarities of acoustic wave reflections at the free boundary of the crystal. A mathematical concept for determination of optical, electrical, and constructional parameters of the filters is developed. Different experimental acousto-optic filters intended for femtosecond pulse shaping are designed and tested. Preliminary experiments are performed in a subpetawatt optical parametric chirped pulse amplification laser system. The experimental data conform completely with the predicted data.

Measurements of fast electron scaling generated by petawatt laser systems

Abstract: Fast electron energy spectra have been measured for a range of intensities between 1018 and 1021Wcm−2 and for different target materials using electron spectrometers. Several experimental campaigns were conducted on petawatt laser facilities at the Rutherford Appleton Laboratory and Osaka University, where the pulse duration was varied from 0.5to5ps relevant to upcoming fast ignition integral experiments. The incident angle was also changed from normal incidence to 40° in p-polarized. The results confirm a reduction from the ponderomotive potential energy on fast electrons at the higher intensities under the wide range of different irradiation conditions.

Chirped-pulse amplification of laser pulses with dispersive mirrors

Abstract: We report a novel implementation of chirped-pulse amplification (CPA) by dominantly using dispersive multilayer mirrors for chirp control. Our prototyp dispersive-mirror (DMC) compressor has been designed for a kHz Ti:sapphire amplifier and yielded--in a proof-of-concept study--millijoule-energy, sub-20-fs, 790-nm laser pulses with an overall throughput of approximately 90% and unprecedented spatio-temporal quality. Dispersive-mirror-based CPA permits a dramatic simplification of high-power lasers and affords promise for their advancement to shorter pulse durations, higher peak powers, and higher average powers with user-friendly systems.

Design considerations for a compact grism stretcher for non-collinear optical parametric chirped-pulse amplification

Abstract: The dispersion management of a non-collinear optical parametric chirped-pulse amplifier is presented. A stretcher based on a combination of a grating and a prism pair (grism) is given and analyzed in detail. This combination can provide up to 300 nm acceptance bandwidth and is suitable for parametric amplification of few-cycle pulses. The amplified pulses can be compressed by the dispersion of optical glasses such as SF57 and the residual high-order dispersion may be compensated by adaptive optical filters and chirped mirrors.

Pulse compression of submillijoule few-optical-cycle infrared laser pulses using chirped mirrors

Abstract: We report generation of 400 microJ, 13.1 fs, 1425 nm optical parametric amplifier laser pulses. Spectral broadening of a 100 Hz optical parametric amplifier laser source is achieved by self-phase modulation in an argon-filled hollow-core fiber, and dispersion compensation is performed using chirped mirrors. This laser source will be useful for ultrafast time-resolved molecular orbital tomography.

Ultra-high power parametric amplifier system at high repetition rates

Abstract: Embodiments of parametric chirped pulse amplifiers seeded with a single pulse source which is subsequently split into a signal arm and a pump arm with appropriate signal and pump conditioning stages are disclosed, which advantageously improve the utility of high average power and/or high energy ultrafast amplification systems. In various embodiments, at least one of the signal or the pump conditioning stages is non-linear, allowing for a great range of seed sources to be utilized. Chirped pulse amplification in the pump conditioning stage may be used to simplify the parametric amplification of pulses with pulse widths of the order of 10 fs. The parametric pump can include coherently combined fiber arrays, hybrid fiber solid-state amplifiers, and/or cryogenically cooled solid-state amplifiers to increase or optimize the energy extraction of high average powers.

Demonstration of SubmicroJoule, Spatially Coherent Soft-X-ray Laser Pumped by 0.1 Hertz, 10 Joule, Picosecond Laser

Abstract: We have demonstrated a spatially coherent 13.9 nm laser with submicroJoule output energy using a double-target geometry with a new driver system. The new driver was a chirped-pulse amplification laser with zigzag slab Nd:glass power amplifiers providing two beams with an energy of 10 J and picosecond duration at a shot rate of 0.1 Hz. The obtained 13.9 nm laser pulse with 1010 coherent photons will enable us to carry out single-shot pump-probe observation of nonperiodic ultrafast phenomena.

Non-collinear optical parametric chirped-pulse amplifier for few-cycle pulses

Abstract: Modified parametric coupled equations for three-wave interaction in non-collinear optical parametric chirped-pulse amplification (OPCPA) are presented, in which the effects from the non-collinear configuration have been taken into account. By utilizing this new model, a two-stage OPCPA system based on a BBO crystal is numerically calculated with a split-step Fourier transform algorithm. Tracing the dynamics of the signal wave in the crystal reveals that in the first stage spectral gain narrowing occurs due to the weak input signal intensity and the non-uniform temporal distribution of the pump light. However, in the saturation regime the spectrum of the signal will be broadened as a consequence of back conversion. The simulation shows that it is crucial to correctly control the experimental parameters to balance both processes. For maximizing the energy-bandwidth product (EBP), an optimized configuration is sought by examining several parameters such as pump intensity, seed energy and crystal length. With a pump intensity of 7.75 GW/cm2 and a crystal length between 3.75 and 4.25 mm pulses with a sub-10 fs duration can be amplified with a total gain of up to 1.7×106.

Nonlinear compression in a rod-type fiber for high energy ultrashort pulse generation.

Abstract: We report the use of nonlinear compression in a very large mode-area rod-type photonic crystal fiber. This fiber allows the use of high energy pulses in the few microjoule range. We demonstrate the compression of 4 µJ, 338 fs pulses from a fiber chirped pulse amplification (FCPA) system down to 49 fs, 41 MW peak power pulses at a repetition rate of 200 kHz with an average power of 400 mW. The nonlinear compression setup is composed of a 5-cm-long rod-type fiber and a pair of SF10 prisms. The system was optimized to obtain good temporal quality, with a temporal Strehl ration of 86 % for the compressed 49 fs pulses.

Supersonic Micro-Jets And Their Application to Few-Cycle Laser-Driven Electron Acceleration

Abstract: This thesis covers the few-cycle laser-driven acceleration of electrons in a laser-generated plasma. The so-called \emph{laser wakefield acceleration} is a long-known concept that relies on strongly driven plasma waves for the generation of accelerating gradients in the range of several 100 GV/m. This value is approximately four orders of magnitude larger than the one attainably by classic accelerators, which is limited essentially by electrical breakdown in the accelerating structures to approximately 100 MV/m. Since the acceleration length necessary for obtaining a certain electron energy is inversely proportional to the accelerating field, this leads also to a drastic reduction of the size and of the price of the accelerator. Furthermore, the special properties of laser accelerated electron pulses, namely the ultrashort pulse duration, the high brilliance, and the high charge density, open up new possibilities in many applications of these electron beams. The laser system employed in this work is a new development based on optical parametric chirped pulse amplification and is the only multi-TW few-cycle laser in the world. It allows for the amplification of pulses with a duration of 8 fs up to a power of 6.5 TW. In the experiment, the laser beam is focused onto a supersonic helium gas jet which leads to the formation of a plasma channel. The laser pulse, having an intensity of 10^19 W/cm^2 propagates through the plasma with an electron density of 2x10^19 cm^(-3) and forms via a highly nonlinear interaction a strongly anharmonic plasma wave. The amplitude of the wave is so large that the wave breaks, thereby injecting electrons from the background plasma into the accelerating phase. The energy transfer from the laser pulse to the plasma is so strong that the maximum propagation distance is limited to the 0.1 mm range. Therefore, gas jets specifically tuned to these requirements have to be employed. The properties of microscopic supersonic gas jets are thoroughly analyzed in this work. Based on numeric flow simulation, this study encompasses several extensive parameter studies that illuminate all relevant features of supersonic flows in microscopic gas nozzles. This allowed the optimized design of de Laval nozzles with exit diameters ranging from 0.15 to 3 mm. The employment of these nozzles in the experiment greatly improved the electron beam quality. After these optimizations, the laser-driven electron accelerator now yields monoenergetic electron pulses with energies up to 50 MeV and charges between one and ten pC. The electron beam has a typical divergence of 5 mrad and comprises an energy spectrum that is virtually free from low energetic background. The electron pulse duration could not yet be determined experimentally but simulations point towards values in the range of 1 fs. The acceleration gradient is estimated from simulation and experiment to be approximately 0.5 TV/m. The electron accelerator is routinely operated at 10 Hz, which is a unique feature among laser based accelerators. The light amplification technique employed in the laser system in principle allows here improvements by several orders of magnitude.

Compensation of Gain Narrowing by Self-Phase Modulation in High-Energy Ultrafast Fiber Chirped-Pulse Amplifiers

Abstract: We propose a method to compensate gain narrowing by use of the self-phase modulation effect in a femtosecond fiber chirped-pulse amplifier (CPA). An engineering rule is derived to determine the stretched pulse duration that allows this compensation. Simulations are carried out to validate this idea. A tradeoff is found between achievable pulse duration and output energy, but we show that this technique allows the generation of 100 fs pulses even for high-gain systems, with output energies of the order of 100 ? J. An experimental proof of principle demonstrates the generation of 112 fs, 10 ?J pulses, the shortest high-energy pulse, to our knowledge, generated by a fiber CPA system.

Controlling the phase matching conditions of optical parametric chirped-pulse amplification using partially deuterated KDP.

Abstract: Using a partially deuterated KDP crystal for an optical parametric amplifier, we demonstrated ultrabroadband optical parametric chirped-pulse amplification of more than 250 nm bandwidth at a center wavelength of 1050 nm. We numerically show how to control the broadband phase matching conditions at different wavelengths to match center wavelengths of suitable broadband seed sources by adjusting the deuteration level in partially deuterated KDP.

Control of the optical Kerr effect in chirped-pulse-amplification systems using model-based phase shaping.

Abstract: Using phase shaping, the impact of the Kerr effect in a fiber-based chirped-pulse amplification (CPA) system is experimentally controlled. The technique is based on an analytical model describing the spectral phase owing to self-phase modulation in CPA systems. The method relies neither on complex phase measurements nor on time-consuming optimization routines. Nearly transform-limited pulses with energies as high as 1 mJ are produced, and a B integral being as high as 8 rad is accumulated in the main amplifier. The value of the B integral is determined by the method itself.

Design of a Femtosecond Ti:sapphire Laser for Generation and Temporal Optimization of 0.5-PW Laser Pulses at a 0.1-Hz Repetition Rate

Abstract: A chirped-pulse amplification Ti:sapphire laser system has been designed using a 10-Hz 100-TW Ti:sapphire laser to generate 0.1-Hz 0.5-PW laser pulses and optimize their temporal qualities such as temporal contrast and pulse duration. A high-energy booster amplifier to be added is expected to produce an energy above 30 J through the parasitic lasing suppression and the efficient amplification. To improve the temporal contrast of the laser pulses, a high-contrast 1-kHz amplifier system is used as a front-end. A grating stretcher which makes the laser pulse have 1-ns duration is used to prevent optical damages due to high pulse energy during amplification. A grating compressor has been designed with group delay analysis to obtain the recompressed pulse duration close to the transform-limited pulse duration. The final laser pulses are expected to have energy above 20 J and duration below 40 fs.

Demonstration of highly efficient broadband amplification in a optical parametric chirped-pulse amplifier system

Abstract: We have demonstrated highly efficient broadband amplification by an optical parametric chirped pulse amplifier (OPCPA) system that uses high energy seed pulses. The OPCPA consists of three type I B-barium borate (BBO) crystals pumped by a Q-switched Nd:YAG laser. We successfully amplified the microjoule level seed pulses to 78 mJ with a pump-to-signal optical conversion efficiency of 26% at a 10 Hz repetition rate. To our knowledge these results represent the most optically efficient OPCPA to date pumped by a typical Q-switched laser.

High Average Power Petawatt Laser Pumped by the Mercury Laser for Fusion Materials Engineering

Abstract: A high average power diode pumped solid state laser is used to pump large aperture Ti:sapphire enabling high average power chirped pulse amplification. After compression, over a petawatt of peak power will be used to generate fusion ions and neutrons for materials testing of first wall and final optics candidates.

Ion acceleration by petawatt class laser pulses and pellet compression in a fast ignition scenario

Abstract: Ion drivers based on standard acceleration techniques have faced up to now several difficulties. We consider here a conceptual alternative to more standard schemes, such as HIDIF (Heavy Ion Driven Inertial Fusion), which are still beyond the present state of the art of particle accelerators, even though the requirements on the total beam energy are lowered by fast ignition scenarios. The new generation of petawatt class lasers open new possibilities: acceleration of electrons or protons for the fast ignition and eventually light or heavy ions acceleration for compression. The pulses of chirped pulse amplification (CPA) lasers allow ions acceleration with very high efficiency at reachable intensities ( I ∼ 10 21 W / cm 2 ), if circularly polarized light is used since we enter in the radiation pressure acceleration (RPA) regime. We analyze the possibility of accelerating carbon ion bunches by interaction of a circularly polarized pulses with an ultra-thin target. The advantage would be compactness and modularity, due to identical accelerating units. The laser efficiency required to have an acceptable net gain in the inertial fusion process is still far from the presently achievable values both for CPA short pulses and for long pulses used for direct illumination. Conversely the energy conversion efficiency from the laser pulse to the ion bunch is high and grows with the intensity. As a consequence the energy loss is not the major concern. For a preliminary investigation of the ions bunch production we have used the PIC code ALaDyn developed to analyze the results of the INFN-CNR PLASMONX experiment at Frascati National Laboratories (Rome, Italy) where the 0.3 PW laser FLAME will accelerate electrons and protons. We present the results of some 1D simulations and parametric scan concerning the acceleration of carbon ions that we suppose to be fully ionized. Circularly polarized laser pulses of 50 J and 50–100 fs duration, illuminating a 100 μ m 2 area of a 20 nm thick carbon target, produce 2 × 10 11 monoenergetic ions of 0.5 GeV with 30% efficiency. Fully 3D simulations show a non-dramatic degradation of the beam properties. In order to reach regimes interesting for the inertial fusion, 1–2 kJ lasers with pulse duration in the 100–500 fs range should be considered with an illuminated surface of few hundreds squared microns, which would insure ∼ 10 12 ions per shot to be produced. The efficiencies would range from 30% to 70% so that the energy of ions would vary from 0.3 to 1.5 kJ. With a few hundreds of such lasers a total energy of ∼ 0.2 – 0.6 MJ , required in the fast ignition scenario, would be reached. By tailoring the space distribution of the beams and their time sequence an adiabatic compression may be reached avoiding the issues related to the charge neutralization in the final focus.

High repetition-rate, all laser diode-pumped extreme ultraviolet/soft x-ray laser and pump system

Abstract: An extreme ultraviolet/soft x-ray laser driven by a compact solid-state chirped pulse amplification laser system entirely pumped by laser diodes is described. The solid-state pump laser generates compressed pulses of sub-10 ps duration with energy greater than 1 J at a chosen repetition rate in a cryogenically cooled Yb:YAG system. Lasing in the 18.9 nm line of Ni-like Mo was observed. The diode-pumped laser has the potential to greatly increase the repetition rate and average power of lasers having a variety of EUV/SXR wavelengths on a significantly smaller footprint.

Implementation of the direct locking method for long-term carrier-envelope-phase stabilization of a grating-based kHz femtosecond laser

Abstract: We have stabilized the carrier-envelope phase (CEP) of amplified femtosecond laser pulses from a grating-based chirped-pulse amplification femtosecond laser by the direct locking method. Long-term CEP stabilization in the oscillator was achieved by employing a double-feedback loop to control both the pumping power and the cavity dispersion. Large CEP drift, induced during amplification, was compensated by adjusting the grating separation in the pulse compressor, and the CEP stabilization was maintained for four hours with a phase jitter of about 180 mrad. After pulse compression to 5.5-fs pulses in a filamentation pulse compressor, CEP-stabilized laser pulses were applied for high-harmonic generation to confirm the CEP stabilization.

Method for generating ultraviolet optical frequency comb drive source

Abstract: The invention relates to a method for generating a drive source of an ultraviolet optical frequency comb. The method comprises the steps of synchronous control of laser and chirped pulse amplification of optical parameters, wherein ultrashort pulses outputted by a laser with stable carrier phase are divided into two beams; one beam is used as signal light to be amplified for chirped pulse amplification of the optical parameters, and the other beam is used for generating synchronous pumping signals through crossed phase modulation or gain selective amplification; picosecond and nanosecond intense pulse laser is taken as a pumping source for chirped pulse amplification of the optical parameters; and ultrashort and ultra-intense laser output is obtained by utilization of compression of grating pairs at an output end for chirped pulse amplification of the optical parameters. The method has the advantages that the method does not need a complex circuit system, can greatly reduce the requirement on the environment and particularly on temperature and vibration, and can obtain the ultraviolet optical frequency comb which has a wider application scope, relatively high power and high repetition frequency and shorter wavelength.