Analysis of Stimulated Raman Scattering of a Giant Laser Pulse

Abstract

When a Raman active material is placed inside the optical Fabry-Perot cavity resonator of a giant pulse (“Q-switched”) laser, the high-power laser light pulse induces gain in the Raman material at frequencies shifted from the giant pulse frequency by well-known Raman frequencies. If this gain is large enough to overcome cavity losses, a strong buildup of coherent light at the shifted frequency(s) may ensue; the process is analogous to stimulated fluorescence and is an example of stimulated Raman scattering. We calculate here the Raman output power as a function of time and its spectral content when the Raman material is in the laser cavity. From the resulting expressions (which contain no undetermined parameters) we calculate the properties of the light generated by nitrobenzene inside a giant pulse ruby laser and find that the results agree with (as yet incomplete) observations that have been made on that system.