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

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.