Quantum fluctuations and soliton formation in stimulated Raman scattering

Abstract

We used the Stokes output from an H2 Raman generator at 10 atm to seed a Raman amplifier. Before entering the amplifier a phase shift was electrooptically placed in the Stokes seed. Although a solitonlike pulse was regularly produced in the pump beam, its amplitude varied greatly. Subsequent studies of the Stokes seed’s power spectrum revealed large shot-to-shot fluctuations. The power spectrum normally consisted of a single near-transform-limited spike whose location jumped from shot to shot and for some shots consisted of two well-resolved spikes. Druhl found theoretically that shifting the Stokes seed slightly off resonance caused the soliton pulse to decay. These frequency fluctuations may thus explain soliton decay. It has also been predicted that solitons will be produced in the output of the Raman generator due to phase shifts resulting from the quantum noise which initiates the Stokes pulse.