Inhibition of stimulated Raman side-scattering with one-dimensional smoothing by spectral dispersion

Smoothing by spectral dispersion (SSD) is a beam smoothing technology aiming at improving irradiance uniformity in laser inertial confinement fusion, which has the potential to suppress many kinds of laser-plasma instabilities. Different effectivenesses of SSD on the suppression of instabilities were reported in previous works, suggesting SSD has different effects on different instabilities under various laser and plasma conditions. In this paper, inhibition of stimulated Raman side-scattering, deduced from the decrease in side-scattered light and hot electrons, in plastic plasmas at moderate laser intensity is observed in experiments with the application of one-dimensional SSD, the reason for which is deduced to be related to the suppression of filamentation. In contrast, two-plasmon decay and backward Raman scattering were not effectively suppressed by SSD in the experiments, the reason for which could be attributed to the limited modulation frequency and the directions of growth with respect to SSD induced rapid motion of laser spots. (C) 2021 Optical Society of America