Widely wavelength tunable Dy³⁺/Er³⁺ co-doped ZBLAN fiber lasers

Wavelength tunable dysprosium-erbium (Dy³⁺/Er³⁺) co-doped ZBLAN (ZrF₄-BaF₂-LaF₃-AlF₃-NaF) fiber lasers pumped at 980 nm were developed with a bulk grating blazed at 3.1 µm in the Littrow configuration and their performances were investigated. A wavelength tunable range of 674.4 nm (2709.2 nm -3373.6 nm) was achieved with a 4.5-m 0.25 mol.% Dy³⁺/ 4 mol.% Er³⁺ co-doped ZBLAN fiber. Our experiments demonstrated that either Er³⁺ or Dy³⁺ can be lasing individually in a Dy³⁺/Er³⁺ co-doped ZBLAN fiber and a fiber laser with wavelength tunable range from 2.7 µm to 3.4 µm or longer wavelengths can be achieved with proper fiber and cavity design.