Pulse shapes and spatial modes in Raman lasers

The steady-state performance of a Raman laser oscillator can be described by a simple standing-wave theory. This theory has been extended to take into account the time variation of the exciting laser pulse. The resulting differential equation is nonlinear, but analytic expressions can be obtained in the limiting cases of small-signal amplification and saturation. Experimental results in H2gas are compared with theory and show good agreement. The phase-matching conditions appropriate to the Raman oscillator are derived and verified experimentally.