Abstract

Stimulated Raman Scattering (SRS) is a convenient means to shift coherently the frequency of an incident laser beam. However, with ultrashort laser pulses SRS is complicated by self-phase modulation (SPM) and self-focusing, both of which become stronger as the input pulse width is reduced. Furthermore, in the transient SRS regime, in which the incident pulse width is shorter than the dephasing time of the Raman material, the Stokes radiation depends on the pulse energy, not the peak power. Thus, Stokes gain does not increase with a decrease in the input pulse width. Here, we used 0.8-ps, 1-mJ, 620-nmlaserpulses to investigate the effects of SPM and self-focusing on the SRS gain in high-pressure hydrogen.

© 1992 IQEC