Abstract

We describe stimulated Raman amplification of a train of pulses of alternating sign in conditions in which multiple pulse effects are important. We previously demonstrated experimentally and theoretically that for a train of nonalternating pulses the Raman gain can grow to be several orders of magnitude greater than that of a single pulse. When the sign of the pulses in either the pump or the incident Stokes train (but not both) alternates, the amplified Stokes pulse train, after an initial transient involving high gain, evolves to a dynamic steady state with an amplitude that can be many orders of magnitude below the corresponding level achieved with a nonalternating train. At its dynamic equilibrium the Stokes amplitude within a pulse oscillates or changes sign depending on the specific conditions. The dependence of the equilibrium Stokes intensity on parameters such as pulse separation and single pulse gain is described. The relationship of the behavior observed here to stationary solutions of the transient Raman equations is explored, and comparisons to effects due to phase oscillations in longer pulses is made.

© 1987 Optical Society of America