Monitoring of molecular species using near-infrared extended cavity diode lasers

Near infrared diode lasers are attractive for spectroscopic applications due to their good spectral purity and low amplitude noise. They operate at room temperature with single-mode output power of milliwatts, and are adapted to fibre optic technology. Wavelength tunability is achieved using an extended cavity configuration. We report on a system based on high resolution infrared spectrometry in the 1.5-1.6 /spl mu/m region where several gases have overtone or combination absorption bands. In monitoring applications toxic and flammable gases like CO and H/sub 2/S are of particular interest. CO detection is aimed at detecting fires with special reference to smouldering combustion within the insulating layers of equipment, whereas H/sub 2/S is a major health hazard on oil rigs producing sour oil.