Simple method for reducing the depolarization loss resulting from thermally induced birefringence in solid-state lasers

A simple technique for reducing the loss that is due to depolarization resulting from thermally induced stress birefringence in solid-state lasers is reported. The technique uses a single intracavity quarter-wave plate with its fast or slow axis aligned parallel to the preferred plane of polarization, defined by an intracavity polarizer. This technique has been applied to a diode-bar-pumped Nd:YAG laser operating at 946 nm, resulting in a measured reduction in depolarization loss from $\sim 1.7\%$ to $\sim 0.0006\%$ and yielding a diffraction-limited, ${\mathrm{TEM}}_{00}$, linearly polarized output power of 2.9 W for an incident pump power of 14.3 W.