Temperature dependence of a Cr4+:YAG passively Q-switched single-longitudinal-mode Nd:YVO4 ring cavity laser

A thermally stable four-mirror discrete-component planar ring cavity for a Cr4+:YAG passively Q-switched single-longitudinal-mode Nd:YVO4 laser is designed to investigate the thermal turning of the laser pulse properties. The cavity parameters are insensitive to the thermal focal lengths of Nd:YVO4 and Cr4+:YAG, which are independently temperature controlled. With a pump power of 5 W at 880 nm, when the heat sink temperature of Cr4+:YAG is fixed, the temperature of Nd:YVO4 is changed to adjust its stimulated emission cross section; its peak power and single-pulse energy are improved from 700 W and 28 μJ to 1900 W and 65 μJ, respectively, as the temperature increases from 0 to 115 °C. The wavelength tuning under these conditions is about 0.034 nm. When the heat sink temperature of Nd:YVO4 is fixed and the temperature of Cr4+:YAG is changed to adjust its ground state absorption cross section, the peak power and single-pulse energy are decreased by 50% and 30%, respectively, as the temperature increases from 0 to 170 °C. As the temperature is adjusted, the cavity does not need to be realigned. At each temperature, the output is a fundamental transverse and single longitudinal mode with stable pulse parameters.