The influence of thermal lens effect on pulse repetition rate in diode-pumped passively Q-switched Nd:GdVO4/V:YAG laser

The influence of thermal lens effect on pulse repetition rate in diode-pumped Nd:GdVO4 1.34 μm laser has been demonstrated. The repetition rate first increased, then reduced with augment of the pump power, for V:YAG with initial transmission (T0) of 96%. The maximum repetition rate was 70 kHz, obtained at the pump power of 6.78 W. The best output laser characteristics—the pulse width of 39.2 ns, the peak power of 2.5 kW and the single pulse energy of 102 μJ—were obtained by V:YAG of T0=89%. With the Gaussian spatial distribution of intracavity photon density being considered, the rate equations were solved numerically and the theoretical calculations agreed with the experimental results.

► The pulse repetition rate firstly increases then drops as the increment of pump power.
► The saturable absorber bleaching factor has the same trend as the repetition rate.
► The thermal lens effect induces the exceptional variation of pulse repetition rate.
► The theoretical calculations are consistent with the experimental results.