Widely Wavelength-Tunable High Power Single-Longitudinal-Mode Fiber Laser in Mid-Infrared Waveband

We demonstrate a mid-infrared (MIR) wavelength-tunable high-power single-longitudinal-mode (SLM) fiber laser using a compound cavity structure. The compound cavity consists of an Er-doped ZBLAN fiber perpendicularly cleaved at two-ends and an external cavity formed by a fiber end-face and a narrow bandwidth ruled reflective diffraction grating. SLM operation is achieved through the combined effects of the narrow bandwidth grating and the compound cavity. By rotating the grating, the laser wavelength can be continuously tuned over 100 nm from 2705 nm to 2806 nm with the SLM operation maintained. High output power up to 450 mW is achieved under the SLM regime.