Suppressing small-scale self-focusing at post-compression by filtering spatial noise in a diffraction-grating compressor

Abstract The results of numerical simulation of spatial noise filtering prior to the stage of nonlinear temporal compression of PW laser pulses are presented. It is shown that small-scale self-focusing (filamentation instability) can be substantially suppressed in a diffraction-grating optical compressor, since the spatial frequencies in the instability region lag behind or overtake the main pulse. This effect in an asymmetric compressor is weaker than in a symmetric one, despite a more efficient smoothing of spatial fluence fluctuations.