Pump-enhanced, Continuous-Wave, Narrow Linewidth Optical Parametric Oscillator at 2.9-3.6 Μm Based on a Fan-out PPLN

Based on a fan-out grating periodically poled lithium niobate (PPLN), a high efficiency, continuous-wave, narrow linewidth, pump-enhanced optical parametric oscillator (OPO) was demonstrated. This OPO exhibited a broad tuning range of 2890-3574 nm, attributable to the unique properties of the fan-out grating PPLN crystal. The OPO achieved over 3 W output power across 2956-3525 nm, due to pump-enhancement technology and an optimized input coupler, whose transmissivity was optimized based on the efficiency on the tuning range. The maximum output power was 4.06 W at 3014 nm. The signal light was employed for locking, resulting in a standard deviation of idler output power of 0.8% over a duration of 30 min. The linewidth of the idler was measured and estimated to be less than 665 kHz. At the maximum output power at 3238 nm, the M2 factors were determined to be 1.25 and 1.33 in the x and y directions, respectively.