Polarization dynamics of intracavity frequency-doubled Nd:YAG laser

Abstract

UDC 621.373Experimental study of low-frequency dynamics of an intracavity frequency-doubled Nd:YAG laser demonstrates the influence of the interaction of orthogonally polarized modes, participating in frequency doubling (type II phase matching), on the stability of the laser output. At a sufficiently low pump rate and low conversion efficiency, the laser shows stable operation with a low noise level at the frequencies of relaxation oscillations. At a high pump power and/or a high conversion efficiency, the laser emission becomes unstable as a result of Hopf bifurcation at the frequencies of relaxation oscillations that are responsible for the anti-phase polarization dynamics of the laser.

Polarisation analysis of optimal conditions for stationary second-harmonic generation in a solid-state laser

“…When polarisations of the laser modes coincide with the directions of the birefringence axes of a nonlinear element (NE), sum-frequency generation of orthogonally polarised modes occurs, resulting in unsteadystate generation if the nonlinear conversion efficiency exceeds a certain critical value [5]. The discrepancy between the laser eigenpolarisations and the directions of the NE axes leads to the appearance of frequency-doubling, which enhances the stability of the steady-state generation process.…”