Aspects of Raman scattering
Abstract
Aspects of stimulated Raman scattering are investigated to better understand the propagation of intense light beams through the atmosphere. In addition, a new unstable resonator cavitie was developed for the long pulse excimer laser used in the Raman beam-cleanup experiments and have made preliminary measurements on an anti-Stokes Raman laser which operates in the vacuum ultra violet region of the spectrum. Experiments demonstrate the Raman gain suppression observed on-axis, or at very small angles, for rotational Raman gain using linearly polarized beams in hydrogen and deuterium. The reduction in vibrational Raman gain at the phase matching angle is noted in hydrogen and deuterium. The normal exponential gain observed in the transient limit was modeled to fit the experiment. The theory had to take account of the actual beam shapes, both spatially and temporally, as well as the self-phase modulation, in order to correctly predict the observed gain functions. Experiments were made on the beam quality and gain dependence of the 2nd Stokes. In particular, a study of the seeding mechanism responsible for generating the 2nd Stokes through the threshold level, has required statistical, spectral, beam profile and gain parameter studies. The far field pattern was then compared with the Fourier transform of the near field pattern to give a measure of the beam quality.
- Publication:
-
Final Report
- Pub Date:
- August 1989
- Bibcode:
- 1989jayc.reptQ....M
- Keywords:
-
- Electron Spin;
- Laser Outputs;
- Near Fields;
- Phase Matching;
- Phase Shift;
- Raman Spectra;
- Cavity Resonators;
- Far Fields;
- Fourier Transformation;
- Pulsed Lasers;
- Raman Spectroscopy;
- Spatial Distribution;
- Stokes Law Of Radiation;
- Ultraviolet Radiation;
- Optics