UBC Theses and Dissertations
Investigation of optical mixing Albach, Gary George
The effect of mixing two intense ruby laser beams in a plasma and in a gas has been investigated by means of light scattering. In both media, large density modulations are shown to exist in the field of the two mixed beams. With plasma, light scattered coherently from a third beam has been observed with intensities of over 100 times that scattered by incoherent thermal fluctuations. Similar enhanced scattering is observed in gases over the normal Rayleigh value. As indicated by the wavevector distribution, the mixed electromagnetic waves produce a stationary density wave in the medium. For gases the dependence of density amplitude on power in the mixed beams and on the gas pressure has been investigated and the results compared to a simple theoretical model. The results indicate that the magnitude of the density modulations saturates with both increasing gas pressure and increasing laser power. A threshold for observation of the density modulations with increasing laser power is also noted in carbon dioxide.
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