Laser-diode-pumped, doubly Q-switched, intracavity optical parametric oscillator considering Gaussian distribution of intracavity photon densities

By considering the Gaussian spatial distribution of the initial population-inversion density and the intracavity photon densities of the fundamental, the signal, and the idle lights, the rate equations of a laser-diode-pumped, doubly Q-switched, intracavity optical parametric oscillator (IOPO) with both acousto-optic modulator (AO) and Cr4+:YAG saturable absorber are derived. The influence of the pump rate, the thermal effect in the gain medium, and the change of the photon density along the cavity axis have also been taken into account the equations. In the experiment, a laser-diode-pumped, doubly Q-switched, Nd:YVO4/KTP IOPO with an acousto-optic (AO) modulator and a Cr:YAG saturable absorber is realized. The shortest pulse width of 6.7 ns has been obtained at the maximum pump power of 6.3 W. The experimental results agree well with the theoretical calculations. (C) 2007 Society of Photo-Optical Instrumentation Engineers.