R. C. Swanson

Stimulated Raman scattering in the visible with a multipass cell

In experimental studies of stimulated Raman scattering in a multipass cell (MPC) with a frequency-doubled single-mode Nd:YAG laser at 532 nm, it is found that only forward Stokes generation is observed and that the growth and saturation of the Stokes beam are in agreement with a simple plane wave, transient theory scaled to account for the focusing, and the multiple passes. The absence of second Stokes generation, backward Stokes generation, and anti-Stoke generation is discussed in terms of the low gain per pass in the MPC. It is concluded that the MPC provides an ideal system for studying stimulated Stokes scattering with visible lasers without the four-wave processes usually seen in a single-focus geometry. >

Quantum Fluctuations in the Stimulated Raman Scattering Spectrum

In this talk we will give physical arguments as to why shot-to-shot fluctuations in the Stokes frequency spectrum occur1. We will present the experimental evidence of these fluctuations first, and then argue that most shots will be near transform limited if the Fourier transform of the Stokes temporal envelope has approximately the same frequency spread as the gain narrowed linewidth. Finally we will explain how we modeled this problem numerically and show that the results of these calculations support our conjecture.

Measurement of quantum fluctuations in the single shot Stokes linewidth in stimulated Raman scattering

Measurements on soliton decay in stimulated Raman scattering have led to the study of frequency fluctuations in the single shot Stokes linewidth. These spectral measurements show that the spectrum of a single shot can be considerably narrower than the gain narrowed profile predicted by quantum mechanics for the ensemble average. However when spectra of many shots are averaged together the predicted result is recovered. The fluctuations seen are thought to be related to the quantum fluctuations associated with the initiating spontaneous emission. Theoretical results based on coherent mode theory are shown to be in agreement with the data.