Gudelev V.G., Svirina L.P., Zhurik Yu.P., and Yasinskii V.M.

Polarization dynamical phenomena in gas lasers
with anisotropic cavities
V.G. Gudelev, L.P. Svirina, Yu.P. Zhurik, and V.M. Yasinskii
Institute of Physics, Academy of Sciences of Belarus,
Minsk, Belarus

We presented the results of the theoretical and experimental study of polarization dynamical phenomena in single-mode standing-wave and ring gas lasers with anisotropic cavities.

It is shown that polarization instability and multistability phenomena in single-mode gas lasers with weakly anisotropic cavities both at and transitions result from spontaneous pulsations of the first or the second kind.

Polarization instability at elliptical orthogonally polarized eigenstates of the empty cavity has been observed experimentally in He-Ne laser [2]. Periodic oscillations of two qualitatively different forms (distorted sinusoids and large spikes), the transition between two stationary orthogonal elliptically polarized waves in the vicinity of the line center tuning, as well as switches of the orthogonally polarized components when the output is nonstationary, have been found. The results of the theory are in perfect agreement with the experiment.

Antiphase stochastic switches and stochastic oscillations of linear orthogonally polarized eigenstates, influenced by spontaneous emission noise have been observed experimentally in a single-mode standing-wave He-Ne ( laser with linear phase and amplitude anisotropy in the cavity and explained theoretically within the vectorial extension of the Lamb's equations written in the form of Langevin [3]. Both of these effects occur in the laser driven by sinusoidal gain modulation across the bifurcation point, which corresponds to the laser first threshold.

Polarization hysteresis and switchings as well as automodulation of intensities of two running orthogonally polarized waves in each direction of propagation have been found experimentally [4] and explained theoretically in a single-mode He-Ne ring laser with anisotropic cavity. The cases of linearly and circularly polarized laser eigenstates have been considered. Mathematical modelling has been carried out in the framework of the matrix approach with the backreflection phenomenon taken into account.

1. L.P. Svirina, Opt. Commun., 111 (1994) 370.
2. V.G. Gudelev, L.P. Svirina, and Yu.P. Zhurik, (submitted to Phys. Rev. A.).
3. V.G. Gudelev, L.P. Svirina, and Yu.P. Zhurik, submitted to Proceedings SPIE "Nonlinear Dynamics in Laser Systems", NDLS'95 International Workshop, St. Peterburg.
4. V.M. Yasinskii, submitted to Proceedings SPIE "Nonlinear Dynamics in Laser Systems", NDLS'95 International Workshop, St. Peterburg.