A novel small-scale self-focusing suppression method for the post-compression in high peak power lasers

Abstract

A novel method, combining an asymmetric four-grating compressor (AFGC) with the pulse post-compression, is numerically demonstrated to improve the spatial uniformity of laser beams and hence to suppress the small-scale self-focusing (SSSF) during the beam propagation in nonlinear materials of high peak power lasers. The spatial uniformity of laser beams is an important factor in performing post-compression, due to the spatial intensity modulation or the hot spots will be aggravated during the nonlinear propagation and then seriously damage the subsequent optical components. The three-dimensional numerical simulations of post-compression are implemented based on a femtosecond laser with a standard compressor and an AFGC, respectively. The simulated results indicate that the post-compression with AFGC can efficiently suppress the SSSF and meanwhile shorten the laser pulses from 30 fs to sub-10 fs. This work can provide a promising route to overcome the challenge of SSSF and will be meaningful to promote the practical application of post-compression technique in high peak power lasers.