Green, holmium-doped upconversion fibre laser pumped by red semiconductor laser

Abstract

Pumping of a green (λ ≃ 549 nm) Ho-doped fluorozirconate glass fibre laser with a high power (~30 mW) singlemode red diode laser is demonstrated. CW output powers exceeding 1.2 mW have been generated from a 22 cm long Ho:ZBLAN fibre for ~24 mW of incident pump power (10.5 mW launched) at 643 nm and a cavity output coupling of 24%. The threshold pump power, 3.5 mW launched (2.1 mW absorbed), is the lowest reported for any upconversion fibre laser. The maximum slope and optical conversion efficiencies measured to date are 18.5 and 12%, respectively, with respect to launched pump power. These results represent the first demonstration of a fibre laser driven by a red semiconductor diode laser.