High-energy kHz mid-IR tunable PPSLT-based OPO pumped at 1064 nm

We report a single-frequency sub-nanosecond optical parametric oscillator (OPO) based on periodically poled stoichiometric lithium tantalate (PPSLT), pumped by a 1064-nm amplified microchip laser at a repetition rate of 0.5 kHz. Using a 11-mm-long PPSLT crystal polled with three different domain periods (30.2, 30.3, 30.4 um) and changing the temperature of the crystal from 20 degC to 265 degC, we have achieved wavelength tuning between 2990 nm and 3500 nm. The high nonlinearity of the used medium and the large aperture (2 mm) ensure the maximum idler output energy of [?]0.5 mJ in the whole tuning range, corresponding to average [?]10.5 % idler conversion efficiency and [?]250 mW of average power. Sub-nanosecond pulse durations have been obtained for the idler at 0.88-ns pulse duration of the pump.