Ultrabroad infrared luminescences from Bi-doped alkaline earth metal germanate glasses

We report on ultrabroad infrared (IR) luminescences covering the 1000–1700-nm wavelength region, from Bi-doped 75GeO₂–20RO–5Al₂O₃–1Bi₂O₃(R = Sr, Ca, and Mg) glasses. The full width at half-maximum of the IR luminescences excited at 980 nm increases (315 → 440 → 510 nm) with the change of alkaline earth metal (Mg²⁺→ Ca²⁺→ Sr²⁺). The fluorescence lifetime of the glass samples is 1725, 157, and 264 μs when R is Sr, Ca, and Mg, respectively. These materials may be promising candidates for broad-band fiber amplifiers and tunable laser resources.