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Physical Review A

Polarization partition noise and intensity fluctuation linewidth in a nearly symmetric vector laser

Sergio Ciuchi, Maxi San Miguel, N. B. Abraham

Published May 1, 1998• 8 citations

Abstract

We consider the statistical properties of the fluctuations in the orientation of the vector laser field for a nearly isotropic laser, addressing the competition between the randomizing influence of noise and the preference for linearly or circularly polarized emission induced by saturation in the laser medium and/or cavity anisotropies. We describe, through a nonperturbative analysis, a crossover regime from diffusion-induced polarization-isotropic emission to emission of nearly fixed polarization characteristics. In this crossover the linewidth of intensity fluctuations associated with one of the circularly polarized components of the vector field amplitude changes from decreasing to increasing with output power. This behavior can be expressed in terms of a single parameter that measures the pump or the total output intensity in terms of the ratio of the noise amplitude to the degree of cross saturation of the amplitudes of the circularly polarized components of the vector field amplitude. Analytical results are given for the linewidth of the intensity fluctuations. When the laser has a preference for linearly polarized emission, there is a weakly non-Lorentzian spectrum in the crossover region. When the laser has a ``preference'' for circularly polarized emission the crossover regime is characterized by a non-Lorentzian spectrum due to fast hopping between two circularly polarized eigenstates. We also describe ellipticity fluctuations induced by the diffusion of the direction of the main axis of the polarization ellipse in the presence of cavity birefringence.

DOI: 10.1103/physreva.57.3843

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