Amplification of Supercontinuum Seed Pulses at 1.1–1.4 m by Cascade Rotational SRS in Compressed Hydrogen

Abstract

Multiple higher-order Stokes of stimulated rotational Raman scattering (SRRS) in compressed hydrogen covered the wavelength range from ~1078 nm to ~1355 nm using ~1.2 ps pump pulses from a Yb:YAG laser. The use of a supercontinuum seed, as well as circular polarization of pump pulses at high hydrogen pressure, made it possible to significantly reduce the threshold for SRRS and suppress vibrational Stokes modes. Cascade excitation of SRRS, corresponding to a shift of 587 cm-1, ensured a spectrum spanning four Stokes orders and a conversion efficiency of 52% with an output energy exceeding 3 mJ. The synthesized spectrum corresponded to ~14 fs transform-limited pulses.