TUNABLE NEAR-INFRARED AND VISIBLE ALL-SOLID-STATE OPTICAL PARAMETRIC OSCILLATOR AMPLIFIER SYSTEM BASED ON POTASSIUM TITANYL PHOSPHATE CRYSTAL

We present the design details and performance characteristics of a low -energy all-solid-state near-infrared optical parametric oscillator am plifier (OPOA). The pump source is a laser diode (LD) pumped frequency -doubled Nd:YAG laser with a single mode energy of 4 mJ in 8 ns, 50 Hz pulses. The OPOA system, based on potassium titanyl phosphate (KTP) c rystal, features a low pump energy threshold at 532 nm of less than 0. 4 mJ, broad tunability from 750 to 1040 nm for the signal and a conver sion efficiency of 27% at 920 nm. External cavity second harmonic conv ersion of the idler to visible green-red light in a type II KTP crysta l and of the signal to visible blue-green light in a type I BBO crysta l was performed with efficiencies up to 10%. We have used the near-inf rared output for wavelength-dependent fluorescence lifetime studies in ytterbium-doped laser materials. We have also used the second harmoni c wavelengths between 565-600 nm to measure the transmission of Nd:YAG in a preliminary experiment to demonstrate the utility of the system.