Pulse Compression in Laser-Diode-Pumped Doubly Q-Switched Intracavity Optical Parametric Oscillator Considering Gaussian Distribution of Intracavity Photon Densities

Abstract

By considering the Gaussian spatial distribution of the initial population-inversion density and the intracavity photon densities of the fundamental, the signal and the idler lights, the rate equations of a laser-diode (LD) end-pumped doubly Q-switched intracavity optical parametric oscillator (IOPO) with both acousto-optic (AO) modulator and Cr4+:YAG saturable absorber are derived. By numerically solving these coupled equations, the dependences of pulse width, pulse energy and peak power on incident pump power for the generated-signal light, whose wavelength is 1.57 µm, are obtained. In the experiment, a LD-pumped doubly Q-switched Nd:GdVO4/KTP (KTiOPO4) IOPO with AO and Cr4+:YAG saturable absorber is realized. The experimental results are compared with those of the AO singly Q-switched IOPO. The doubly Q-switched IOPO can generate the shorter pulse width and higher peak power than that of the AO singly switched one when the input diode power is about from 5.2 to 6 W. The experimental results agree with the theoretical values well.