Implementation of fluorophoshate laser glass for short length active fiber at 1.5 μm

•The fluorophosphate laser glass was implemented as short length active glass fiber.•The rod-in-tube technique was used for the fabrication of glass fiber.•The Tg and refractive index of glasses were optimized to make the glass fiber.•The spectroscopic properties of fluorophosphate laser glasses were evaluated.•The gain characteristics were demonstrated for fiber amplifier at 1.5 μm. We successfully fabricated a short-length active fiber based on fluorophosphate (FP) laser glass by the rod-in-tube technique and fiber drawing process. The base FP laser glass composition, 20Al(PO3)3-40BaF2-40SrF2 was used for making glass fiber with appropriate core and clad profiles. The physical, thermal, optical, and spectroscopic properties of core and clad materials were optimized in order to implement FP laser glass for active glass fiber fabrication. The difference of refractive index and the glass transition temperature between core and clad glass ingots was obtained to be close to 0.004 and 6 °C, respectively. The spectroscopic properties of FP laser glasses were also derived. The gain and gain coefficient of the indigenously fabricated glass fiber were measured to be 10.29 dB and 0.60 dB/cm at 1550 nm from a 17 cm bare fiber, respectively. The results direct that the short length active fiber based on FP laser glass could be useful for compact all-optical fiber amplifier at 1.5 μm.