Phase instability in a four-frequency anisotropic-ring cavity gas laser

The nonlinear dynamics of a class A four-frequency ring gas laser with elliptic nonorthogonal states of counterpropagating waves is studied based on a developed and experimentally tested model taking explicitly into account the dependence of the backscattering coefficient of counterpropagating waves on polarisation characteristics. It is shown that the instability of phase characteristics of the generated field cause the switching of the intensities, polarisation states, and phase differences of counterpropagating waves in the self-oscillation regime, the shift of the intensity switching over detuning caused by the phase shift of the wave due to nonzero ellipticity, the spontaneous phase symmetry breaking accompanied by the appearance of deterministic and noise-induced chaos, the multistability of attractors with different topologies, and symmetric and asymmetric chaotic, as well as stochastic oscillations.