EFFICIENT LOW-ENERGY NEAR-INFRARED KTIOPO4 OPTICAL PARAMETRIC CONVERTER

We report a widely tunable near-infrared holosteric KTiOPO4 optical pa rametric converter featuring a low pump energy threshold and high conv ersion efficiency. The converter uses two 10-mm-long crystals in a sim ple optical parametric oscillator amplifier configuration and is tunab le from 750 to 1040 nm for the signal. The pump energy threshold at 92 0 nm is 0.44 mJ for the 532-nm 8-ns 50-Hz input. The system produces a s much as 0.45 mJ of energy at 920 nm with an external pump-to-signal energy conversion efficiency of 27% for pump inputs from just two time s the threshold value. The internal pump-to-signal and idler energy co nversion efficiency is estimated to be 58%. The low pump energy requir ement of this system makes it compatible with small laser-diode-pumped solid-state lasers.