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

Fluoroindate glass fibers with an Er³⁺ doping concentration of ∼0.5mol% were fabricated by using a rod-in-tube method. Pumped by a 976 nm laser diode, intense emission at ∼3.3µm was obtained from a 40 cm long Er³⁺-doped fiber, which could be attributed to the transition ⁴S_3/2→⁴F_9/2 of Er³⁺ ions. The calculated emission cross section at ∼3.3µm was ∼3×10^-26m², which was ∼1.5 times larger than that of transitions Er³⁺:⁴F_9/2→⁴I_9/2 and Dy³⁺:⁶H_13/2→⁶H_15/2. 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 ∼3.3µm fiber lasers.