Abstract

A computer movie illustrating a rigorous multimode calculation of SF, St, Prb buildup in Raman studies is presented. This coherent copropagational study based on Maxwell-Bloch formalism¹ includes phase and transverse variations, nonlinear asymmetric dispersion, pump spatial depletion, and time-dependent variations in population inversion density. Theλ scheme is selected so that the active transitions are optically thick for both the pump (α_pl > 5) and the SF (α_sfl > 35) pulses. This choice of Beer lengths, i.e., of oscillator strengths, insures that the two pulses never cease to overlap and optimizes the SF initially small signal growth. The pump interacts like a self-induced transparency while the SF, St, Prb evolves as a small-area in a two-level emitter which can be described as a nonlinear pendulum in the pane wave. For a given ratio of Beer lengths, distinct Fresnel numbers, atomic density numbers, small signal SF, St, Prb time-integrated energy stabilization or self-focusing may arise, as observed experimentally. For a sufficiently larger propagation distance, an asymptotic evolution of a quasisolitary nonhyperbolic-secant pulse of constant area is reported.

© 1986 Optical Society of America