Thermal modeling of the continuous-wave end-pumped Q-switched lasers

The transient temperature profiles in continuous-wave (cw) end-pumped Q-switched lasers are investigated by solving a numerical model coupling the transient heat conduction equation and the rate equations, in which the influences of the thermal time constant, the fluorescence lifetime and the repetition rate on the temperature variation are considered. Furthermore, the buildup dynamics of thermal equilibrium in several laser crystals are presented and compared with each other. The numerical simulation results reveal that the buildup time of thermal equilibrium mainly depends on the thermal time constant, however, the temperature rise is primarily influenced by the absorption cross section. Compared with the influences of the other parameters, fluorescence lifetime principally determines the thermal oscillation contrast. In addition, it is also found that the repetition rate and the pump power have significant effects on the thermal characteristics in Q-switched lasers.