Suppression of power losses during laser pulse propagation in underdense plasma slab

For current state-of-the-art terawatt lasers, the primary laser scattering mechanisms in plasma include forward Raman scattering (FRS), excitation of plasma waves, and the filamentation instability. Using 2D particle-in-cell (PIC) simulations, we demonstrate that FRS dominates in the regime with medium-to-low density plasma and non-relativistic laser fields. We numerically show that FRS can be suppressed using a two-color laser with frequency detuning exceeding the plasma frequency, Delta omega > omega pe, leading to a more efficient laser energy transmission. An optimal laser pulse energy redistribution ratio is predicted analytically and verified by PIC simulations.