11.7 mW green InGaAs-laser-pumped erbium fibre laser

A room-temperature erbium-doped fluoride glass upconversion fibre laser generated 11.7 mW of 544 nm continuous-wave laser light when pumped by a 150 mW, 971 nm InGaAs semiconductor laser. A similar laser system, enclosed in a compact (432cm3) package produced 4 mW of green laser light. A long time-constant hysteresis effect in the excitation mechanism, as well as active electronic noise reduction are discussed.