Towards Terawatt Sub-Cycle Long-Wave Infrared Pulses via Chirped Optical Parametric Amplification and Indirect Pulse Shaping

Abstract

We present an approach for both efficient generation and amplification of 4–12 μm pulses by tailoring the phase matching of the nonlinear crystal Zinc Germanium Phosphide (ZGP) in a narrowband-pumped optical parametric chirped pulse amplifier (OPCPA) and a broadband-pumped dual-chirped optical parametric amplifier (DC-OPA), respectively. Preliminary experimental results are obtained for generating 1.8–4.2 μm super broadband spectra, which can be used to seed both the signal of the OPCPA and the pump of the DC-OPA. The theoretical pump-to-idler conversion efficiency reaches 27% in the DC-OPA pumped by a chirped broadband Cr2+:ZnSe/ZnS laser, enabling the generation of Terawatt-level 4–12 μm pulses with an available large-aperture ZGP. Furthermore, the 4–12 μm idler pulses can be compressed to sub-cycle pulses by compensating the tailored positive chirp of the idler pulses using the bulk compressor NaCl, and by indirectly controlling the higher-order idler phase through tuning the signal (2.4–4.0 μm) phase with a commercially available acousto-optic programmable dispersive filter (AOPDF). A similar approach is also described for generating high-energy 4–12 μm sub-cycle pulses via OPCPA pumped by a 2 μm Ho:YLF laser.

Enhancing keV high harmonic signals generated by long-wave infrared lasers

“…CEP stable few-cycle lasers centered at 800 nm have been the working horse for generating single isolated attosecond pulses [2]. When the seed pulses of the 8 micron laser are generated with the 800 nm laser such as the architecture described in [8], the precision synchronization of the two pulses can be accomplished optically and the CEP of the 8 micron pulse can be stabilized. At a given ionization probability, the intensity of the 800 nm pulse can be chosen by finding an acceptable compromise between the cutoff photon energy and the X-ray signal strength.…”

“…When the intensity of the 800 nm pulse is one fifth of the 8 micron pulse, the cutoff reaches a higher value than that when the intensity ratio is one to three, the enhancement of the X-ray intensity is less (but still more than two orders of magnitude around 4 keV). The requirement of the intensity of the quasi-single-cycle 800 nm pulse can be met with Ti:Sapphire lasers followed by a hollow-core fiber compressor, which seeds the 8 micron laser [8].…”

“…In the last decade, mJ-level driving lasers centered in the 1.3 to 4 µm range have been developed for generating X-ray pulses in the water-window region (282 to 533 eV) and beyond [4][5][6][7]. Long-wave infrared (LWIR) lasers centered at 8 μm are being designed [8] to develop attosecond X-ray sources covering the photon energy range of 1 to 5 keV.…”

Generation of high-energy narrowband 205 μm pulses for seeding a Ho:YLF laser

“…However, the spectral bandwidth has not reached one octave, which limits the pulse duration to multicycle. We have designed a scheme for generation of terawatt subcycle 4-12 μm pulses through OPCPA in ZGeP 2 pumped by an Ho:YLF laser [30]. Because the signal of the OPCPA is from a Ti:sapphire laser and the pump is from an Ho:YLF laser, the Ho:YLF laser should also be derived from the Ti:sapphire laser in order to facilitate synchronization between the signal and the pump.…”

Attosecond Light Sources in the Water Window

“…Simulation results for generating 4-12 μm idler pulses in a 0.4 mm ZGP OPCPA pumped by a 2 μm narrowband laser. Reproduced from[35]. CC BY 3.0.…”