Non-collinear Optical Parametric Chirped Pulse Amplification Research Articles

Efficient noncollinear optical parametric chirped-pulse amplification in oversaturation region

Optical parametric chirped pulse amplification (OPCPA) is the workhorse to generate intense ultrashort pulses across a broad wavelength range. Typically, OPCPA operates in the saturation region, but barely in the oversaturation region due to efficiency drop caused by back conversion. Through numerical simulations, we reveal the potential of noncollinear OPCPA to achieve significantly higher conversion efficiency in the oversaturation regime compared to the recognized saturation efficiency. This enhancement stems from the suppression of back conversion facilitated by noncollinearity-induced idler dissipation. Besides offering high efficiency and robustness, the oversaturated noncollinear OPCPA also exhibits acceptable spatial and temporal properties, as well as spatiotemporal coupling properties. These findings hold promise for enhancing the final stage of a noncollinear OPCPA system, where a high conversion efficiency is essential.

Evolution of orbital angular momentum spectrum of broadband Laguerre–Gaussian beam in OPCPA process

In this study, we numerically simulate the evolution of the orbital angular momentum (OAM) spectrum of a vortex laser beam in the optical parametric chirped pulse amplification (OPCPA) process, which is an effective technical method to realize ultra-intense and ultra-short vortex laser amplification. The results show that the proportion of the vortex laser beam with 100% topological charge (TC) of 1 decreases to 97.44% with the enhancement of the saturation amplification after amplification by a 15 mm length LBO pumped by a 526.5 nm laser with a pump intensity of 1.74 GW/cm2. Conversely, the beams with other topological charges generate and increase with the amplification. The simulation results are consistent with our previous experimental results. Meanwhile, compared with non-collinear OPCPA, collinear OPCPA can maintain well the proportion of TC l = 1.

Optical parametric amplification at critical wavelength degeneracy—a proposed approach for 100-PW class femtosecond laser development

At signal critical wavelength degeneracy (CWD), super-broad parametric gain bandwidths (SBGBs) can be obtained in nonlinear crystals. A 280 nm SBGB, for ∼60 small signal peak gain, has been calculated considering a collinear optical parametric chirped pulse amplification (OPCPA) at CWD in a 40 mm long, 58.3% partially deuterated KDP (P-DKDP) crystal, pumped by a frequency doubled nanosecond Nd:glass laser at 1 GW/cm2 pump intensity. This gain bandwidth in the 1 µm spectral range is significantly broader compared to the 150 nm gain bandwidth, calculated under similar conditions, for the broad-band non-collinear (NC) OPCPA in DKDP crystals in the 900 nm spectral range. It can support the amplification of significantly shorter femtosecond pulses, giving rise to a higher peak power at the same amplified pulse energy. The spectral profile of the gain bandwidth can be shaped by slightly adjusting the deuteration ratio (DR) of the P-DKDP crystals. A small-angle non-collinear OPCPA near the CWD can be used for the spatial separation of the signal and idler beams with the same polarization, keeping at the same time an ultra-broad gain bandwidth. A SBGB of 255 nm FWHM has been calculated for a non-collinear OPCPA stage with a 40 mm long P-DKDP crystal, 10.3 mrad signal-pump wavevectors internal angle, 57.8% DR, pumped by a few-ns 527 nm wavelength laser at 1 GW/cm2 pump intensity. The half-meter size P-DKDP crystals, pumped by frequency doubled few-ns multi-kJ Nd:glass lasers, are able to amplify super broad-band nanosecond stretched pulses up to the kJ energy level. They might be appropriate amplifying media for the development of single-beam 100-PW class femtosecond laser systems based on OPCPA at CWD.

Simulating an ultra-broadband concept for Exawatt-class lasers

The rapid development of the optical-cycle-level ultra-fast laser technologies may break through the bottleneck of the traditional ultra-intense laser [i.e., Petawatt (PW, 1015 W) laser currently] and enable the generation of even higher peak-power/intensity lasers. Herein, we simulate an ultra-broadband concept for the realization of an Exawatt-class (EW, 1018 W) high peak-power laser, where the wide-angle non-collinear optical parametric chirped-pulse amplification (WNOPCPA) is combined with the thin-plate post-compression. A frequency-chirped carrier-envelope-phase stable super-continuum laser is amplified to high-energy in WNOPCPA by pumping with two pump-beamlets and injected into the thin-plate post-compression to generate a sub-optical-cycle high-energy laser pulse. The numerical simulation shows this hybrid concept significantly enhances the gain bandwidth in the high-energy amplifier and the spectral broadening in the post-compression. By using this concept, a study of a prototype design of a 0.5 EW system is presented, and several key challenges are also examined.

Generation of Terawatt-Scale Vortex Pulses Based on Optical Parametric Chirped-Pulse Amplification

In this letter, we report the demonstration of terawatt (TW)-scale femtosecond vortex laser pulses based on noncollinear optical parametric chirped-pulse amplification (OPCPA) centered at 800 nm. To the best of our knowledge, this is the first experimental study of amplification for OPCPA-based vortex pulses to achieve a powerful ultrafast (TW-scale) vortex pulse output. In this experiment, a 0.5-mJ broadband chirped vortex pulse was amplified to 47 mJ with a 15-mm-long LiB3O5 crystal. The double-pass grating pair compressor with an efficiency of 65% maintained the beam vortex, and a pulse of width 30.1 fs was obtained, corresponding to a peak power of 1.02 TW. This laser can be used in studies on nonlinear optics and relativistic laser-plasma interactions, compact plasma-based accelerators, and light sources.

Ultra-broadband all-OPCPA petawatt facility fully based on LBO

Abstract A petawatt facility fully based on noncollinear optical parametric chirped pulse amplification (NOPCPA) technology, Vulcan OPPEL (Vulcan OPCPA PEtawatt Laser), is presented. This system will be coupled with the existing hybrid-CPA/OPCPA VULCAN laser system (500 J, 500 fs beamline; 250 J, ns regime beamline) based on Nd:glass amplification. Its pulse duration (20 times shorter) combined with the system design will allow the auxiliary beamline and its secondary sources to be used as probe beams for longer pulses and their interactions with targets. The newly designed system will be mainly dedicated to electron beam generation, but could also be used to perform a variety of particle acceleration and optical radiation detection experimental campaigns. In this communication, we present the entire beamline design discussing the technology choices and the design supported by extensive simulations for each system section. Finally, we present experimental results and details of our commissioned NOPCPA picosecond front end, delivering 1.5 mJ, ~180 nm (1/e2) of bandwidth compressed to sub-15 fs.

Ultra-broadband near-infrared NOPAs based on the nonlinear crystals BiBO and YCOB

AbstractWe evaluate and demonstrate ultra-broadband near-infrared noncollinear optical parametric amplification in two nonlinear crystals, bismuth borate (BiBO) and yttrium calcium oxyborate (YCOB), which are not commonly used for this application. The spectral bandwidth is of the microjoule level; the amplified signal is ≥ 200 nm, capable of supporting sub-10 fs pulses. These results, supported by numerical simulations, show that these crystals have a great potential as nonlinear media in both low-energy, few-cycle systems and high peak power amplifiers for terawatt to petawatt systems based on noncollinear optical parametric chirped pulse amplification (NOPCPA) or a hybrid.

Possible method for a single-cycle 100 petawatt laser with wide-angle non-collinear optical parametric chirped pulse amplification

A single-cycle (3 fs) 100 petawatt laser pulse is obtained theoretically by dramatically increasing the spectrum, accordingly reducing the pulse duration, of the optical parametric chirped pulse amplification (OPCPA) with a new designed wide-angle non-collinear OPCPA (WNOPCPA). While comparing with two other recent popular methods of the energy-further-increased single-beam femtosecond petawatt laser and the spatiotemporally coherent combination of multiple-beam femtosecond petawatt lasers, we believe that the proposed method is another choice for sub-exawatt lasers.

High average power 88 W OPCPA system for high-repetition-rate experiments at the LCLS x-ray free-electron laser.

We present a 100kHz, sub-20fs optical parametric chirped-pulse amplifier (OPCPA) system delivering 88.6W average power at a center wavelength of 800nm. The seed pulses are derived from the pump laser via white-light continuum generation and are amplified in three non-collinear OPCPA stages. The final two high-power stages are pumped with a 661W Yb:YAG InnoSlab amplifier. A simple and robust design is used for the OPCPA system to avoid thermal effects and enhance long-term stability, resulting in excellent beam quality and high conversion efficiency. To the best of our knowledge, this is the highest average power OPCPA system reported to date.

Scanning broadband optical parametric chirped pulse amplification based on optical beam deflection

One of the goals pursued in laser pulse is to achieve a laser with a shorter duration and higher intensity. In the past two decades, the laser pulse duration has been shortened by more than 7 orders of magnitude due to the development of Q-switched, Mode-locked and pulse compression technology. The peak power of laser pulse has been increased to PW, even EW and ZW from initial MW with the development of pulse amplification technology, whose focused intensity can reach to 10<sup>23</sup> W/cm<sup>2</sup>. Thus, it provides unprecedented extreme conditions, and speeds up the laser applications in ultrafast nonlinear optics, strong field physics, fast ignition of laser nuclear fusion, optic communication, etc. The optical parametric chirped pulse amplification (OPCPA) is one of the important technologies in ultra-short laser pulse field. It is of great significance to increase the gain bandwidth for improving the conversion efficiency of OPCPA and achieving broadband optical parametric amplification. Combining the optical beam deflection and non-collinear OPCPA, a novel scanning broadband OPCPA model is proposed based on the optical beam deflection. The basic principle of increasing the gain bandwidth for the scanning broadband OPCPA is analyzed theoretically, which ensures the phase matching of each frequency component of signal by optical beam deflecting to change the non-collinear angle constantly. Namely, the non-collinear angles of incident frequency components of signal are different from each other, which, however, makes the whole phase matching of signal, i.e. momentum conservation in optics. The optical parametric amplification of signal pulse with 800 nm central wavelength and almost 100 nm bandwidth is simulated numerically by the proposed scanning broadband OPCPA. The results show that the bandwidth after being amplified is almost the same as before and there is no spectral narrowing, and the scanning broadband OPCPA increases the gain bandwidth and conversion efficiency greatly compared with the amplification with a constant given non-collinear angle, which leads to broadband optical parametric amplification. Finally, it is necessary to make sure that the on-load voltage to the KTN crystal matches with the frequency of signal pulse in time and reduces the unfavorable voltage deviation and time-delay for the maximizing gain bandwidth and conversion efficiency and ensuring the phase matching of each signal frequency component. The results of this paper not only provide an approach to increasing the gain bandwidth of OPCPA, but also supply some theoretical references and the basis for the experimental work of OPCPA in ultra-short laser pulse system.

Sub-4 fs laser pulses at high average power and high repetition rate from an all-solid-state setup.

The generation of high average power, carrier-envelope phase (CEP) stable, near-single-cycle pulses at a repetition rate of 100 kHz is demonstrated using an all solid-state setup. By exploiting self-phase modulation in thin quartz plates and air, the spectrum of intense pulses from a high-power, high repetition rate non-collinear optical parametric chirped pulse amplifier (NOPCPA) is extended to beyond one octave, and pulse compression down to 3.7 fs is achieved. The octave-spanning spectrum furthermore allows performing straightforward f-to-2f interferometry by frequency-doubling the long-wavelength part of the spectrum. Excellent CEP-stability is demonstrated for extended periods of time. A full spatio-spectral characterization of the compressed pulses shows only minor asymmetries between the two perpendicular beam axes. We believe that the completed system represents the first laser system satisfying all requirements for performing high repetition rate attosecond pump-probe experiments with fully correlated detection of all ions and electrons produced in the experiment.

Optimizing the performance of non-collinear optical parametric chirped pulse amplification via multi-pass structure based on two geometry configurations.

We propose a method for multi-pass non-collinear optical parametric chirped pulse amplification (MNOPCPA) based on two geometries, tangent phase-matching (TPM) and Poynting vector walk-off compensation (PVWC), which optimize the performance of optical parametric chirped pulse amplification (OPCPA). A feasible design scheme is also presented for use in implementing this approach. Employing this design, we construct and perform a numerical simulation, showing that back-conversion from the signal and idler to the pump can be inhibited, and that the conversion efficiency can be boosted dramatically, approaching the theoretical limit of ~64%, when amplification is nearly saturated at full bandwidth. In the MNOPCPA scheme, the output signal has a wider spectrum and a corresponding shorter Fourier-limited pulse duration with the pump being continuously depleted. A barycenter shift of the signal spot results from a spatial walk-off effect due to the pump, which can be offset and corrected well. To the best of our knowledge, this is the first demonstration of a multi-pass non-collinear OPCPA method employed the scheme of regenerative amplification.

Numerical investigation of output beam quality in efficient broadband optical parametric chirped pulse amplification

We theoretically analyzed output beam quality of broad bandwidth non-collinear optical parametric chirped pulse amplification (NOPCPA) in LiB3O5 (LBO) centered at 800nm. With a three-dimensional numerical model, the influence of the pump intensity, pump and signal spatial modulations, and the walk-off effect on the OPCPA output beam quality are presented, together with conversion efficiency and the gain spectrum. The pump modulation is a dominant factor that affects the output beam quality. Comparatively, the influence of signal modulation is insignificant. For a low-energy system with small beam sizes, walk-off effect has to be considered. Pump modulation and walk-off effect lead to asymmetric output beam profile with increased modulation. A special pump modulation type is found to optimize output beam quality and efficiency. For a high-energy system with large beam sizes, the walk-off effect can be neglected, certain back conversion is beneficial to reduce the output modulation. A trade-off must be made between the output beam quality and the conversion efficiency, especially when the pump modulation is large since. A relatively high conversion efficiency and a low output modulation are both achievable by controlling the pump modulation and intensity.

Numerical investigations of non-collinear optical parametric chirped pulse amplification for Laguerre–Gaussian vortex beam

We present for the first time a scheme to amplify a Laguerre–Gaussian vortex beam based on non-collinear optical parametric chirped pulse amplification (OPCPA). In addition, a three-dimensional numerical model of non-collinear optical parametric amplification was deduced in the frequency domain, in which the effects of non-collinear configuration, temporal and spatial walk-off, group-velocity dispersion and diffraction were also taken into account, to trace the dynamics of the Laguerre–Gaussian vortex beam and investigate its critical parameters in the non-collinear OPCPA process. Based on the numerical simulation results, the scheme shows promise for implementation in a relativistic twisted laser pulse system, which will diversify the light–matter interaction field.

Visualization of high-order dispersion for compression of few-cycle pulses

We present a visually intuitive method for higher-order dispersion compensation based on multi-photon interpulse interference pulse scans. The dispersion values obtained from these scans are fed back as a correction to an acousto-optical programmable dispersive filter to compensate residual higher-order dispersions up to fifth order. This method is applied to the dispersion management of a non-collinear optical parametric chirped-pulse amplifier. A grism-pair stretcher is designed based on a global dispersion balance which provides a large stretching factor and supports a spectral bandwidth of up to 320 nm. It is implemented in a two-stage three-pass non-collinear optical parametric chirped-pulse amplifier and stretches 6-fs seed pulses to about 80 ps from 700 to 1,000 nm. The amplified pulses are compressed by material dispersion. Pulses of less than 10-fs duration with a pulse energy of 125 μJ are obtained at 20-kHz repetition rate.

SNR improvement based on non-collinear OPCPA with angular spectral dispersion in BBO crystal

The characteristics of the signal-to-noise ratio (SNR) improvement based on non-collinear optical parametric chirped pulse amplification (OPCPA) with angular spectral dispersion (ASD) was revealed and investigated. The angular dispersion formula was derived theoretically and the effects of crystal length, pump peak intensity, noise characteristics and angular dispersion on the SNR improvement and conversion efficiency were discussed. Furthermore, by optimizing the critical parameters, 35% conversion efficiency and more than 3 orders of magnitude of SNR improvement were achieved for the chirped signal pulse with a central wavelength of 800nm, pumped by 532nm in presented amplification scheme with BBO crystal.

Mismatch characteristics of optical parametric chirped pulse amplification

The stability of an optical parametric chirped pulse amplifier (OPCPA) is influenced by time and the angular matching of the input beams. We derived the Gaussian dependence of the monochromatic signal gain on the small mismatch between the signal and pump beams. Gain characteristics were also calculated for polychromatic amplification and the impact of different beam mismatches and interaction geometries was explained. The asymmetry of the energy gain, and the square root dependence of the phase matched wavelength on beam angles were found. The predicted dependences were verified in a noncollinear OPCPA system with LBO and KDP crystal amplifying pulses of a Ti:sapphire laser around a central wavelength of 800 nm, pumped by the third harmonic frequency of an iodine gas laser at a wavelength of 438 nm. The widths of the gain curves in the dependence on both the pump–signal or the phase matching angles varied from several tenths to a few milliradians. The gain curve widths dependent on the pump–signal pulse delay were about two thirds of the pump pulse width for moderate pumping and about a half of the pump pulse width for pumping on the order of GW cm−2. A stable gain output is achieved if angular and temporal fluctuations are fractions of the measured gain curve widths, and when the signal direction is between the pump and the crystal principal axis (i.e. in the psz geometry).

Generation of 120 GW mid-infrared pulses from a widely tunable noncollinear optical parametric amplifier

We demonstrate a noncollinear optical parametric chirped-pulse amplification scheme for generating high-peak-power tunable mid-infrared (IR) pulses. The high-gain LiNbO(3)-based noncollinear parametric amplifier, seeded by a tunable femtosecond optical parametric amplifier, provides a wide wavelength tuning range from 3.3 to 3.95 μm and a large saturated gain of over 4000 in a single-stage amplifier. The compressed mid-IR pulse has a pulse energy of 13.3 mJ and pulse duration of 111 fs, with a peak power as high as 120 GW. To the best of our knowledge, this is the highest peak power ever reported for 3-5 μm tunable mid-IR lasers.

Design Considerations for Dispersion Control with a Compact Bonded Grism Stretcher for Broadband Pulse Amplification

We report on the design of a compact grism-pair stretcher for a near-infrared noncollinear optical parametric chirped-pulse amplification (OPCPA) system. The grisms are produced by bonding a grating to a prism using a resin. The stretcher is capable of controlling a bandwidth of over 300 nm, which is suitable for parametric amplification of few-cycle pulses. After amplification, pulses can be compressed by the dispersion of optical glass, and the residual group-delay can be compensated with an acousto-optic programmable dispersive filter (AOPDF).

Experimental demonstration of joule-level non-collinear optical parametric chirped-pulse amplification in yttrium calcium oxyborate

In this Letter, we report on what is, to our knowledge, the first experimental demonstration of yttrium calcium oxyborate (YCOB) for joule-level and broadband non-collinear optical parametric chirped-pulse amplification centered at 800 nm. Based on a Ti:sapphire chirped-pulse amplification front end, an amplified signal energy of 3.36 J was generated with a pump of 35 J in the crystal. Compressed pulse duration of 44.3 fs, with a bandwidth of 49 nm, was achieved. The results confirm that YCOB crystal is another potential alternative as a final amplifier besides Ti:sapphire in a petawatt laser at 800 nm.