Title :
The stimulated Raman scattering threshold for a nondiffraction-limited pump beam
Author :
van den Heuvel, J.C. ; van Putten, F.J.M. ; Lerou, R.J.L.
Author_Institution :
TNO Phys. & Electron. Lab., The Hague, Netherlands
fDate :
9/1/1992 12:00:00 AM
Abstract :
The threshold power of stimulated Raman scattering (SRS) has been calculated for various nondiffraction-limited pump beams using a numerical model. These calculations were performed for the following pump beam profiles: Gaussian-Hermite, Gaussian-Laguerre, Gaussian-Schell-model (GSM), and several superpositions of Gaussian-Hermite modes. It is shown that the threshold power, for a tightly focused beam, depends on the M2 factor, which is a dimensionless factor that compares the divergence of a given beam with the divergence of a (diffraction-limited) Gaussian beam, related to the pump beam quality. The influence of the exact pump beam profile on the threshold is small. It is shown that the measured SRS thresholds in methane for two pump beams, one with an M2 of 1.12 and the other with M2=8.7, correspond with the calculated thresholds for two GSM beams with the same M2
Keywords :
laser beams; optical pumping; organic compounds; stimulated Raman scattering; Gaussian Laguerre model; Gaussian-Hermite modes; Gaussian-Schell-model; dimensionless factor; divergence; methane; nondiffraction-limited pump beam; numerical model; pump beam profiles; pump beam quality; stimulated Raman scattering threshold; threshold power; tightly focused beam; GSM; Gaussian processes; Laser beams; Laser excitation; Laser theory; Lenses; Numerical models; Pump lasers; Raman scattering; Stimulated emission;
Journal_Title :
Quantum Electronics, IEEE Journal of
