BACKWARD STIMULATED RAMAN SCATTERING

This paper describes in detail the initiation and growth of backward-traveling stimulated Raman-Stokes pulses. The radiation-transfer equations for the pulse development are derived, and a general analytic solution is given in the rate-equation approximation. Special solutions are given for a variety of pulse-initiation conditions. It is shown that in the presence of residual linear absorption, a steady-state Stokes pulse is expected, and its characteristics are described. Extensive experimental observations in CS2 of the properties of the backward pulse and the forward emission are reported, including measurements of the pulse energy as a function of position in the cell, the pulse duration as measured by the intensity-autocorrelation technique, and the time sequence of the emission of the forward and backward pulses. Various experimental results indicate the dominant role played by self-focusing in the initiation of the backward pulse and the role of competing processes. The growth of the pulse energy is found to be consistent with the theory; a minimum pulse duration of 30 psec and a peak pulse power 20 times the instantaneous laser pump power are reported, indicating substantial depletion of the incident laser pump light. © 1969 The American Physical Society.