3μm watt level Dy: ZBLAN all-fiber high-power lasers

The mid-infrared band fiber lasers are very important for fundamental research and industrial applications. Mid-infrared fiber lasers in the 2 - 3.5 μm spectral region have been widely used in many fields, including gas remote sensing, molecular detection, material processing, and biomedicine. In this letter, by splicing the fluoride fiber and the quartz fiber, the 976 nm pump light was fused to a 6 m, 7 mol.%, Er³⁺:ZBLAN fiber system. With the fluoride fiber grating as the resonator, a 11.7 W continuous light output at 2.8 μm was achieved, realizing a high-power, all-fiber 2.8 μm laser. The laser center wavelength was 2826.6 nm, the maximum slope efficiency was 21.7%, and the beam quality M² < 1.12. Through the research on the direct writing inscription of fluoride fiber gratings, the grating with a Bragg reflection wavelength of 3.2 μm was fabricated on Dy³⁺: ZBLAN fiber. Using the high-power 2.8 μm all-fiber laser as the pump source, it was fused to a 2.7 m, 0.2 mol.%, Dy³⁺:ZBLAN fiber system through a single-mode ZBLAN fiber. Two self-inscribed fiber Bragg gratings (FBGs) with reflectivities of 99.68% and 30.5% respectively were used to construct an all-fiber Fabry-Perot laser cavity. A 3.8 W continuous light output at 3.2 μm was achieved under a pump power of 7.7 W, realizing a high-power, all-fiber 3.2 μm laser. The laser center wavelength was 3198.97 nm, the measured slope efficiency was 53.0%, the maximum optical-to-optical efficiency was 49.4%, and the beam quality M² < 1.12.