Abstract

Self-phase modulation (SPM) in a Kerrlike medium has been widely used to produce the chirp with following pulse compression.¹ To compress a high energy laser pulse it is necessary to use large aperture bulk material because of damage limitations. The phase shift and the degree of compression is proportional to the so-called breakup integral B which is also a measure of small-scale self-focusing. It has been known that the spatial quality of the beams is quickly degraded in B 2-3² so that a large degree of SPM and compression in a single sample of nonlinear medium is impossible.^3,4 SPM in a bulk medium can be obtained through multiple passes in optical resonators⁵ but the compression may be limited by a large-scale self-focusing, nonuniform infensify distribution and a bandwidth of the amplifier medium.

© 1993 Optical Society of America