Approaches towards cross-beam energy transfer for short laser pulses

Processing ultra-intense laser pulses through stimulated Raman scattering in plasmas has shown promising results. With two counter-propagating pulses, backward Raman amplification can transfer the energy of a long pump pulse to a short and sharp seed pulse. The excited plasma waves mediate rapid energy transfer between laser pulses. We show, through 2D PIC simulations, that the plasma waves can also mediate energy transfer between two crossing beams through near-forward Raman scattering. In that case, as our 2D PIC simulations show, the energy transfer can also be mediated through filamentation instability. However, the extent to which this filamentation usefully combines beams, or disadvantageously destroys focusability, is a key question.