Highly efficient, cascaded extraction optical parametric amplifier

The scheme of cascaded extraction optical parametric amplifier (CE-OPA) has been proposed as a final amplifier for high peak power laser systems. 4D numerical simulations show that conversion efficiency of a CE-OPA system pumped with a temporal Gaussian pump pulse is as close to the theoretical limit of quantum efficiency as a conventional OPA pumped with temporal flat-top pump pulse. The CE-OPA system is also similar to the conventional scheme in output energy stability and alignment sensitivity of the phase-matching angles, too. However, with the use of the CE-OPA scheme, the requirement of pump pulse shaping can be relaxed, leading to an overall higher plug in efficiency as well as compact design. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Design of a thin disk amplifier with extraction during pumping for high peak and average power Ti:Sa systems (EDP-TD)

Combination of the scheme of extraction during pumping (EDP) and the Thin Disk (TD) technology is presented to overcome the limitations associated with thermal cooling of crystal and transverse amplified spontaneous emission in high average power laser systems based on Ti: Sa amplifiers. The optimized design of high repetition rate 1-10 PW Ti: Sapphire EDP-TD power amplifiers are discussed, including their thermal dynamic behavior. (C) 2016 Optical Society of Americ

High peak and average power Ti:sapphire thin disk amplifier with extraction during pumping

The combination of the extraction during pumping (EDP) amplification scheme and the thin disk (TD) technology has been successfully applied to the Ti:sapphire (Ti:sa) laser medium for the first time, to the best of our knowledge. In a proof-of-principle experiment, we demonstrate high energy broadband amplification in a room temperature water cooled EDP-TD head of stretched femtosecond pulses at a 10 Hz repetition rate, instead of performing a cryogenically cooled traditional multi-pass scheme. Hence, the EDP-TD combination can overcome the limits associated with thermal effects and transverse amplified spontaneous emission, enabling Ti:sa laser systems to have a petawatt peak and hundreds of watts of average power. (C) 2016 Optical Society of Americ

Broadband spectral characterization of the phase shift induced by population inversion in Ti:Sapphire

The spectral phase shift of broadband amplified pulses, induced by population inversion, was measured in Ti:Sapphire at different pump fluence values. The measurement was performed for two orthogonal polarization directions and at two different crystal temperatures of 296 K and 30 K. Zero shifts and sign changes were observed in the spectral phase, which are connected to the gain spectrum of the crystal. The electronic refractive index changes were also numerically calculated by the Kramers-Kronig theory. The results are highly important for achieving sub-10 fs pulse duration and phase stability in the next generation of Ti:Sapphire-based laser systems. © 2019 Optical Society of America

Generation of subcycle isolated attosecond pulses by pumping ionizing gating

We present a novel approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a pre-existing gas grating, creating a fast-extending plasma grating(FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a sub-cycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency up-conversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs fromlong picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6-ps, 1-{\mu}m pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%.These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity.Comment: It provides a new way to generate isolated attosecond pulse(IAP) by a picosecond pump, which has a protential to boost the IAP energy to joule leve

Polarization-encoded chirped pulse amplification in Ti:sapphire: a way toward few-cycle petawatt lasers

The bandwidth of titanium sapphire (Ti:Sa) laser amplifiers can be greatly broadened with shaping the spectral gain via engineering the spectral polarization of amplified pulses and using both pi- and sigma-cross-sections. In a proof-of- principle experiment, an amplification bandwidth exceeding 85 nm at a gain of 200 was demonstrated. The accompanying computer modeling revealed that a polarization-encoded chirped pulse amplification scheme can be scaled to higher energies and thus can produce multijoule pulses with bandwidth close to 200 nm, making few-cycle petawatt Ti: Sa systems feasible. (C) 2015 Optical Society of Americ

Suppression of Pulse Intensity Dependent Dispersion during Nonlinear Spectral Broadening with Intermediate Compression for Passive CEP Stable Pulse Generation

The intensity fluctuation induced spectral phase-change of the laser pulse during nonlinear spectral broadening is theoretically investigated. The oscillation of the phase-change curves at the central part of the spectra is explained by the two-wave interference model, while the bending of the phase-change curves at the wings is considered to originate from the intensity dependent dispersion caused by the self-steepening (SST) effect. Both of them can degrade carrier envelop phase (CEP) stability after an intra-pulse difference frequency generation (IP-DFG) setup. We propose an effective approach to suppress the intensity dependent dispersion with intermediate compression. Verified by numerically simulations, well-phased spectral components at the wings can be obtained, which is highly beneficial for CEP stable pulse generation with noisy input