Generation of extreme ultraviolet laser by single-photon process

TL;DR

This paper demonstrates a novel single-photon excitation method to generate a 58.4 nm EUV laser with higher efficiency than traditional multi-photon processes, using stimulated anti-Stokes Raman scattering in helium.

Contribution

It introduces a new single-photon process for EUV laser generation, surpassing the efficiency of high harmonic generation and demonstrating coherent, stimulated emission at 58.4 nm.

Findings

Achieved 58.4 nm laser with higher efficiency than HHG.

Demonstrated stimulated anti-Stokes Raman scattering in helium.

Produced pulsed EUV laser with 426 ps decay time.

Abstract

To generate laser with short wavelength is a bottle-neck problem in laser technology. The extreme ultraviolet (EUV) lasers are usually produced with low efficiency by nonlinear multi-photon process. Here we show the generation of 58.4 nm laser by a single-photon-excitation related stimulated anti-Stokes Raman scattering (ASRS) with an efficiency higher than that of high harmonic generation (HHG). Utilizing microwave excited helium in the metastable 1s2s state irradiated by a resonant femto-second 2058 nm laser, we obtain pulsed 58.4 nm laser with a divergence of 1.9 mrad, suggesting its coherent character. The pulse decay time of 426 ps shorter than the lifetime of spontaneous emission also shows its stimulated property. Our results show an applicable path towards up-conversion by single-photon process to generate intense laser with wavelength shorter than 58.4 nm.