Tunable, Dual-Wavelength, Single-Crystal, Continuous-Wave Optical Parametric Oscillator

We demonstrated tunable, dual-wavelength (DW), continuous-wave mid-infrared generation in single-PPLN-based optical parametric oscillator (OPO) which was pumped by a DW Raman fiber laser located at 1060 and 1110 nm. Based on a singly resonant oscillator design, this device permits access to arbitrary signal and idler wavelength combinations within the parametric gain bandwidth and reflectivity of the OPO cavity mirrors. By tuning PPLN temperature, two pairs of signal and idler beams were obtained with arbitrary tuning across 1607-1626 nm and 3081-3583 nm. The frequency separation in the resonant signal waves was down to 5.7 THz. Moreover, near wavelength-matched condition, energy coupling between the resonant signal waves, resulted in reduced operation threshold and increased output power. A total DW output power (>6.8 W) is obtained. The experiment results exhibited great potential in mid-infrared generation using low-power pump beam with special characteristics.