Polarisation dynamics of single-longitudinal-mode Nd:YAG lasers with a weakly anisotropic cavity

The polarisation dynamics of a single-mode bipolarisation chip Nd:YAG laser with a weak phase anisotropy of the cavity is studied experimentally and theoretically. It is shown that the three types of relaxation oscillations exist in the bipolarisation lasing regime, the two of which are responsible for the antiphase dynamics of orthogonally polarised modes. It is demonstrated that pumping by linearly polarised radiation induces the gain anisotropy. It is found that the main properties of the low-frequency polarisation dynamics and the induced gain anisotropy are almost independent of the orientation of crystallographic axes of the active element. The model of a single-mode bipolarisation solid-state laser, which was developed earlier and takes into account the phase-sensitive interaction between orthogonally polarised modes, well describes the main properties of the low-frequency polarisation dynamics observed in experiments.