Thermally Induced Nonlinear Refraction in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te

Self-focusing of laser beams is observed in Cd$\text{}_{0.5}$Mn$\text{}_{0.5}$Te at room temperature. The far-field patterns of laser beam after passing through the cadmium manganese telluride crystal are investigated. The values of focal length as well as the absorption coefficient were measured as a function of intensity of laser radiation. From these measurements the values of nonlinear refractive index for Cd$\text{}_{0.5}$Mn$\text{}_{0.5}$Te are determined. The results indicate that the self-focusing observed in Cd$\text{}_{1-x}$Mn$\text{}_{x}$Te is due to a thermally induced change in refractive index.