Repetitive Q-Switching of a CW Nd:YAG laser using Cr4+:YAG saturable absorbers

Repetitive Q-switching of a CW pumped Nd:YAG laser using a Cr4+:YAG saturable absorber was achieved for the first time, providing pulses 80-300 ns wide (FWHM) with repetition rates ranging between 2 and 29 kHz. Different ranges of repetition rates and pulse widths are obtained by using absorbers of different optical densities. Satisfactory quantitative description of the experimental results is obtained by a full numerical solution of the system rate equations according to the theory of Powell and Wolga. These equations involve the dynamics of the laser population inversion, the absorber state population, and the photon density in the laser cavity.