ALL-SOLID-STATE CW MODE-LOCKED PICOSECOND KTIOASO4 (KTA) OPTICAL PARAMETRIC OSCILLATOR

We report on an experimental investigation and numerical analysis of a noncritically phase-matched KTiOAsO4 (KTA) optical parametric oscilla tor (OPO) synchronously pumped by a cw diode-pumped mode-locked Nd:YVO 4 oscillator-amplifier system. The laser system (pumped by 84 W of cw 808-nm diode radiation) generates 7-ps-long pulses at 1.064 mu m with a repetition rate of 83.4 MHz and an average power of 29 W. The OPO, s ynchronously pumped by the 1.064-mu m laser pulses, consists of a 15-m m-long KTA crystal (cut for type TI noncritical phase-matching) in a f olded signal resonant linear resonator. The average powers of the 1.54 -mu m signal radiation and the 3.47-mu m idler radiation are 14.6 W an d 6.4 W, respectively. The total OPO output of 21 W corresponds to an internal efficiency of 75%. The experimental investigations include me asurements of the OPO output power (and its dependence on the pump pow er, the transmission of the output coupler, and the resonator length) and of the pulse properties (such as pulse duration and spectral width ). The measured results are in good agreement with the predictions of a numerical analysis based on a split-step Fourier method.