Laser-diode side-pumped actively Q-switched eye-safe intracavity optical parametric oscillator

Eye-safe laser of 1573 nm wavelength from a laser-diode (LD) side-pumped actively Q-switched Nd:YAG/KTP intracavity optical parametric oscillator (IOPO) with acousto-optic (AO) modulator is presented. The dependences of the average output power, the pulse width, pulse energy, and the peak power on incident pump current for the generated-signal-light pulses are obtained. By considering the Gaussian spatial distributions of the pump light in laser medium, the photon densities of the fundamental, the signal, and the idle waves as well as the initial population-inversion density and the coupled rate equations of this IOPO are described, in which 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 been also taken into account. These coupled equations are solved numerically, and the theoretical calculations are consistent with the experimental results.