Intense emission at ∼3.3 μm from Er³⁺-doped fluoroindate glass fiber

Fluoroindate glass fibers with an Er³⁺ doping concentration of ∼0.5 mol% were fabricated by using a rod-in-tube method. Pumped by a 976 nm laser diode, intense emission at ∼3.3 µm was obtained from a 40 cm long Er³⁺doped fiber, which could be attributed to the transition ⁴S₃/₂ → ⁴F₉/₂ of Er³⁺ ions. The calculated emission cross section at ∼3.3 µm was ∼3 × 10⁻²⁶ m², which was ∼1.5 times larger than that of transitions Er³⁺ : ⁴F₉/₂ → ⁴I₉/2 and Dy³⁺ : ⁶H₁₃/₂ → ⁶H₁₅/2. In addition, broad emissions ranging from 3.1 µm to 3.85 µm were obtained in the Er³⁺doped fiber under a 976 nm/1973 nm dual-wavelength pumping scheme. Our results indicated that Er³⁺-doped fluoroindate glass fibers had the potential for constructing efficient ∼3.3 µm fiber lasers.