Time-dependent analytical model of thermal effects in continuous-wave end-pumped Tm:YAP lasers

A time-dependent analytical thermal model of temperature and stresses is developed to investigate the transient behavior of thermal effects in continuous-wave (CW) end-pumped laser rods. To validate the model, it is applied to a CW pumped Tm:YAP crystal and found to be in very good agreement with results of solving heat-transfer equation by finite-difference method and experimental results. The temperature contribution coefficient and stress contribution coefficient are derived from the analytical model. The temperature contribution coefficients obtained from analytical and numerical models are 1.29 K/W and 1.14 K/W, respectively. For the stress contribution coefficient of 0.34 MPa/W, the permissible maximum pump power of similar to 471 W is obtained. The focal lengths of the Tm:YAP is measured in the range of 40 similar to 90 mm, when the pump power is between 16 and 34 W.