Compact CW mid-IR Fe:ZnSe coherent source pumped by Er:ZBLAN fiber laser

We report the first-of-its-kind compact and robust coherent source operating in mid-IR based on Fe:ZnSe chalcogenide gain medium optically pumped by Er:ZBLAN fiber laser. In the research, we study the CW operation of cryogenically cooled laser based on Fe:ZnSe single crystals with different doping level grown from the vapor phase on a single-crystal seed by using the concurrent-doping technology. The maximal output power achieved is 2.1 W with 59% slope efficiency with respect to absorbed pump power, which is close to the Stokes shift limit. Measured Fe:ZnSe output spectra indicate a significant influence of re-absorption on generation wavelength. For high doping levels and output powers, spectrum shifts to the red wing, which makes possible continuous tuning from 4012 to 4198 nm. As well, tunability of the laser in a wide range of temperature is investigated.