Nonlinear model of thermal effects in YAG:Nd laser crystals

A nonlinear (steady-state) model of thermal effects in YAG:Nd is proposed: it takes into account the real temperature dependence of the thermal conductivity of the active medium. Equations are derived for the stresses, the maximum theoretical heat release, and the optical power of the thermal lens for an active element in the form of a long circular rod. It is shown that these equations contain new dependences and describe the experiments considerably more accurately than the relationships of the linear model. When the cooling rate is increased, the nonlinear equations yield the familiar relationships of the linear approximation.