Widely Tunable Narrow-Linewidth Continuous-Wave MIR Laser at 2.2-5.1 μm

A widely tunable narrow-linewidth continuous-wave (CW) mid-infrared (MIR) laser was realized with a PPMgO:LN-based optical parametric oscillator (OPO) pumped by a 1060 nm single-frequency fiber laser. The MIR laser tuning with a range from 2250.7 to 5092.7 nm was obtained using the two multi-period PPMgO:LN crystals. The output power was larger than 520 mW@2250.7-4000 nm, 160 mW@4000-4300 nm, and 15 mW@4300-5095.4 nm, where the maximum output power of 4.64 W@2500 nm was obtained with an optical-to-optical conversion efficiency of 15.5%. The linewidth was measured to be ~0.41 MHz at 3300 nm using the delayed self-homodyne method. The output power stability was measured to be RMS = 1.43% for 8 h. The beam quality factors at 2786, 3360, and 4453 nm were 1.18, 1.19, and 1.26, measured using the knife-edge method. Finally, an engineering prototype was developed using high-reliability engineering design and system integration. Our results will play a significant role in the development of widely tunable narrow-linewidth MIR lasers.