Compact and Tunable Mid-IR Light Source Based on a Dual-Wavelength Fiber Laser

A compact, tunable mid-IR difference-frequency generation (DFG) light source based on a dual-wavelength fiber laser and a 5mol% MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal is developed and evaluated. An output power of 233 μW is achieved with a conversion efficiency of 0.1%/W. The mid-IR wavelength can be tuned between 3308 nm and 3314 nm by changing the temperature of a pair of fiber Bragg grating (FBG) taking as cavity mirrors in the dual-wavelength fiber laser from 26.5°C to 106.5°C.