Efficient diode pumped Tm 3+ -doped fluoridefibre laser forhydrocarbon gas sensing

Abstract
The operation of a 2.31 µm CW thulium-doped fibre laser, pumped by a low power 785 nm diode-laser is reported. A 2 mW output power combined with a high slope efficiency make this fibre laser ideal for sensing hydrocarbon gases, which absorb at 2.3 µm. A limit of detection of ~1000 ppm metres for methane is demonstrated using an unoptimised system.