660 nm and 974 nm Dual-Wavelength Pumped Er3+/Dy3+ Codoped ZBLAN Fiber Laser

In this work, we experimentally report a wavelength -tunable Er3+/Dy3+ codoped ZBLAN fiber laser via employing the strategy of 660 nm and 974 nm dual-wavelength pumping, for the first time, to our knowledge. Based on the combined effects of the ${}^{4}\mathrm{F}_{\mathrm {9/2}}\to {}^{4} \mathrm{I}_{\mathrm {9/2}}$ and ${}^{6}\mathrm{H}_{\mathrm {13/2}}\to {}^{6} \mathrm{H}_{\mathrm {15/2}}$ transitions from Er3+ and Dy3+ ions, respectively, the tunable spectral range of $2930\sim 3681$ nm (751 nm) was obtained, representing the broadest level of rare-earth-doped mid-infrared fiber lasers. More importantly, the gain distribution of the laser could be managed by controlling the ratio of the dual-wavelength pump powers, hence yielding an ultraflat subrange of $3.2\sim 3.4~\mu $ m, with a low power fluctuation of <3% around 700 mW. This dual-wavelength pumped architecture provides an optional mid-infrared photonics platform for designing broadband tunable oscillators and amplifiers.