The thermally induced stress birefringence has been known to affect severely the performance of a solidstate-laser system when the beam is linearly polarized. This study analyzes the birefringence as a function of the YAG :Nd rod-axis orientation; this investigation illustrates the angular dependence of birefringence for directions other than the  crystal direction and describes the losses for various rod-axis and polarizer orientations.
W. KOECHNER and D. K. RICE, "Birefringence of YAG: Nd Laser Rods as a Function of Growth Direction," J. Opt. Soc. Am. 61, 758-766 (1971)