High-sensitivity two-dimensional thermal- and mechanical-stress-induced birefringence measurements in a Nd:YAG rod

A novel polarimeter for measuring the two-dimensional (2D) thermal- and mechanical-stress-induced birefringence in solid-state laser materials such as Nd:YAG is proposed. Using this device, we could sensitively measure the direction of the principal birefringence axis as well as the phase shift δ with sign when δ < π/4. The 2D thermal- and mechanical-stress-induced birefringence in a laser-diode-pumped Nd:YAG rod was successfully measured with the proposed polarimeter. We also found an active quarter-wave Nd:YAG phase retarder.