A Review of Polarization Properties and Output Mechanisms in Isotropic Solid-State Lasers

Abstract

In isotropic solid-state lasers, polarization control remains a challenging yet crucial aspect, especially in the absence of intrinsic birefringence. Recent studies have revealed that linearly polarized output can be realized through mechanisms such as pump polarization influence, stress- and symmetry-induced anisotropies, and frequency locking between polarization eigenmodes. This review summarizes key experimental findings and theoretical interpretations, including polarization self-selection originating from dopant site symmetry and the emergence of coherent eigenmode superposition under specific cavity conditions. While significant progress is made, most models remain confined to low-power or single-mode regimes and overlook complex behaviors in multimode, high-power scenarios. Future research should emphasize multi-physics coupling, spatiotemporal polarization diagnostics, and full-field simulation methods to bridge the gap between theoretical mechanisms and practical implementations.