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 nearinfrared (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 hollowcore fibers which supports sub-cycle pulse duration.

Ultra-broadband near-infrared pulse generation by noncollinear OPA with angular dispersion compensation

“…In order to theoretically assess the feasibility of the idler beam generated in a NOPA as our ultra-broadband seed, and to estimate the achievable energy and bandwidth from the available PFS front end, we used a simple 1D model to calculate the three-wave mixing process of the OPA for our laser parameters [20,24]. The OPA is pumped with the second harmonic of the Ti:sapphire source, which is centered at 395 nm, and the seed beam is assumed to be of Gaussian shape in frequency space resulting in a bandwidth ranging from 500 to 900 nm.…”

“…Since the final goal of our experiment is to produce an ultra-broadband, high-energy, high-contrast seed pulse for the short-pulse-pumped OPCPA chain of PFS, we used its already available front end, a modified Femtopower Compact Pro system (Femtolasers GmbH). This consists of a Ti:sapphire oscillator and multipass amplifier with a sub- sequent hybrid pulse compressor [20], delivering up to 1.4-mJ pulses with a duration of around 30 fs centered around 800 nm at a repetition rate of 1 kHz.…”

“…For optimum contrast of the output beam, the OPA stages should be seeded with a high-contrast pulse at an energy level as high as possible. As a common front end for the pump-laser chain and the main OPCPA chain a modified version of a commercially available Ti:sapphire source is used (for full details see [1,20]). State-of-the art supercontinuum generation in a filament or hollow-core fiber can in principle generate a sufficiently broad spectrum, albeit in the range between 400 nm and 900 nm, while a spectral shift towards the near infrared is hard to achieve when starting from an 800-nm pump source [21].…”

“…Moreover, the temporal contrast that can be achieved through these schemes has not been quantified so far and remains a reason for concern. The feasibility of generating the PFS seed pulse using plasma filaments, hollow-core fibers or a combination of both is detailed in [20].…”

Generation and Parametric Amplification of Few‐Cycle Light Pulses at Relativistic Intensities

“…The initial approach to generate the OPCPA seed pulses in the spectral range from 700 nm to 1400 nm using the output of the Femtopower was developed by Izhar Ahmad and Sergei Trushin and is described in [53]. It consists of two cascaded hollow core fibers (HCF) and applies the widespread HCF compression technique to produce fewcycle or even sub-cycle pulses from a multi-cycle input [14,[120][121][122][123][124].…”