Abstract

We previously reported both experimental and theoretical results for transient Raman amplification by a train of pulses with identical phase. In that case the Raman amplification can be several orders of magnitude greater than for a single pulse. The increased Raman amplification is due to the phase memory of the Raman medium. When the pulses in either the pump or the seed-Stokes pulse train are given alternating reversed phases, however, the Raman amplification in the train can be reduced dramatically and, in some conditions, even driven below the single-pulse amplification level. Early experiments using eight pulses with a single phase reversal after the fourth pulse confirm a reduction in pulse train amplification. We report results for the Raman amplification obtained by using a train of eight pulses with alternating phase. The alternating phases are created by passing the train of pulses through an electrooptic modulator set for phase modulation and driven by an rf signal of sufficient intensity to achieve a complete phase reversal for adjacent pulses.

© 1988 Optical Society of America