Abstract: A diode pumped optical parametric oscillator is disclosed. The apparatus includes a MOPA laser positioned to pump a photorefractive BaTiO3 crystal placed within a ring resonator formed by four mirrors. The interaction of the MOPA laser light incident on the BaTiO3 crystal and with the light reflected within the cavity efficiently converts the MOPA pump beam to a single frequency beam of high beam quality. Once the pump beam exceeds a threshold power level, it interacts with a nonlinear periodically poled lithium niobate crystal received within the ring cavity. The lithium niobate crystal efficiently converts the pump beam to signal and idler beams of different wavelengths, providing an efficient, tunable laser.