Theory and Modeling of Stimulated Raman Scattering
FYSISCH EN ELEKTRONISCH LAB TNO THE HAGUE (NETHERLANDS)
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A three-dimensional finite difference method is presented for the propagation through a gain medium of beams focused by an astigmatic lens. The method is used for the modeling of a Raman amplifier that uses astigmatic lenses. With this method, the effect of gain focusing on the amplification is studied. The numerical results show a good correspondence with analytical models in the range where these models are applicable. The threshold power of stimulated Raman scattering SRS has been calculated for various nondiffraction-limited pump beams using the numerical model. It is shown that the threshold power, for a tightly focused beam, depends on the M squared factor that is related to the pump beam quality. Additionally, the influence of the exact pump beam profile on the threshold is small. Therefore, the M squared factor is a useful parameter for analyzing the experimental threshold. We show that the measured SRS thresholds in methane correspond with the calculated thresholds.
- Numerical Mathematics