Hydrogen Chloride Gas Monitoring at 1.74 µm with InGaAs/InGaAsP Strained Quantum Well Laser

Abstract
A distributed feedback laser with 1.9% compressive strain in the InGaAs/InGaAsP quantum wells is demonstrated at 1.74 µm. The characteristic temperature was 66 K, and the wavelength tuning rate was 0.016 nm/mA. A laser monitoring system of hydrogen chloride gas and the laser shows a good linear calibration curve from 10 ppm to 1% concentration of hydrogen chloride gas diluted in nitrogen. The detection limit of HCl/N2 was 0.7 ppm for the present experimental setup.