Dynamics of emission from a linear gas laser with periodically varying anisotropy directions

A theoretical investigation is made of the operation of an He–Ne laser at λ = 1.15 μm with periodically varying directions of its anisotropy. It is shown that rotation and simultaneous sinusoidal vibration of an anisotropic active modulator results in the generation of laser radiation with spontaneous oscillations of the intensity and ellipticity. The range of control parameters m and Ω₂ (amplitude and frequency of the modulator vibrations), resulting in a parametric resonance characterized by an abrupt change in the velocity of rotation of the polarization ellipse, is found. A diagram of lasing regimes with different dynamics is calculated as a function of the values of m and Ω₂. It is shown that a second Andronov–Hopf bifurcation gives rise to an invariant torus for certain values of m and Ω₂.