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Gas sensing with lambda = 1.57 micrometer distributed feedback laser diodes using overtone and combination band absorption
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1994
Year
EngineeringDfb Laser DiodesCombination Band AbsorptionGas SensorLaser ApplicationsAbsorption SpectroscopyChemistryChemical EngineeringOptical PropertiesOptical DiagnosticsOptical SensorLaser-based SensorPhotonicsLaser DiodesLaser SpectroscopyGas DetectionDetection LimitOptical SensorsElectrochemical Gas SensorLaser PhotochemistryNatural SciencesSpectroscopyApplied PhysicsTunable LasersOptoelectronics
Spectral measurements of the <i>v</i><sub>1</sub> + <i>v</i><sub>2</sub> + <i>v</i><sub>3</sub> combination absorption band of H<sub>2</sub>S were made over a 10-nm wavelength range around 1.57 m with two tunable distributed feedback (DFB) laser diodes. Targeting the strongest observed H<sub>2</sub>S absorption feature, a detection limit at atmospheric pressure of 50 ppm/m is indicated from the measured detectivity at higher concentration. We also probed the 2<i>v</i><sub>1</sub> + 2<i>v</i><sub>2</sub> + <i>v</i><sub>3</sub> overtone and combination absorption band of CO<sub>2</sub> and investigated the dependence of absorption linewidth on pressure and assessed its implications for expected low-detection limits. These results demonstrate the utility of DFB laser diodes for industrial applications in the area of toxic and trace gas monitoring.