Q switching of a diode-pumped Nd:YAG laser with GaAs

We investigated the properties of a diode-pumped Nd:YAG laser that is passively Q switched by a thin, singlecrystal GaAs wafer. At 3 W of incident pump power, the laser produced stable 7-ns pulses with 20 microJ of energy at a 6-kHz repetition rate. For pump powers up to 2.2 W, which resulted in 13.2-microJ pulses, the output mode was TEM(00). The shortest pulses that we observed were 3 ns in duration. In addition to saturable absorption, we find that two-photon absorption and free-carrier effects determine pulse formation.