All-fiber tunable ring laser source near 2 μm designed for CO2 sensing

A continuous-wave tunable thulium-doped all-fiber ring laser near 2 μm under in-band pumping at 1.6 μm has been demonstrated in the filterless configuration, specifically to act as a compact and simple laser source for gaseous carbon dioxide detection. The laser parameters suitable for tunable operation have been identified through numerical modelling and subsequent experimentation. A laser power of 8 mW with a tunable range of 36 nm (in between 1968 to 1932 nm) is demonstrated by intracavity loss variation. This laser configuration can be superior to the FBG-based configurations due to the possibility of a wider tuning range as compared to the latter.