Production of radially or azimuthally polarized beams in solid-state lasers and the elimination of thermally induced birefringence effects

TLDR

Thermally stressed isotropic laser rods cause different focusing for radially and tangentially polarized light. Nd:YAG laser oscillators were engineered to produce low‑loss, stable single‑polarization oscillation. The authors produced and amplified radially and azimuthally polarized Nd:YAG beams up to 150 W, achieving high beam quality (M² = 2–2.5) and polarization purity while completely eliminating thermal‑birefringence‑induced aberrations, thereby enabling superior beam quality in rod‑based high‑power lasers.

Abstract

Production and amplification of radially and azimuthally (tangentially) polarized laser beams are demonstrated. Based on the different focusing between radially and tangentially polarized light in thermally stressed isotropic laser rods, Nd:YAG laser oscillators were developed to produce low-loss stable oscillation in a single polarization. Pure radially polarized light at 70 W with M2=2 and on-axis impure radially polarized light at 150 W with M2=2.5 were achieved. The radially polarized beams were then amplified while good beam quality and polarization purity were retained. Complete elimination of thermal-birefringence-induced aberrations was demonstrated. This should allow much better beam quality from rod-based high-power lasers.