Study of thermally induced active birefringence in Nd: glass laser rods

A study of active birefringence arising due to the thermal stresses in Nd:glass laser rods under different experimental conditions of pumping is reported. The extent of birefringence was measured in terms of depolarization of a pulsed probe beam from a Q-switched Nd:YAG (yttrium aluminum garnet) laser. The maximum depolarization for a 38-mm-diam rod pumped by 12 xenon flash lamps in a circular diffuse reflector configuration was determined to be 2.3%. This value for the depolarization as well as its radial profiles agree well with those determined from a cylindrically symmetric gain profile. In cases of deviation from the cylindrically symmetric pumping, the observed birefringence was found to be more for a clover leaf reflector as compared to that for a circular diffused reflector.