A laser-based sensor for selective detection of benzene, acetylene, and carbon dioxide in the fingerprint region

A mid-infrared laser-based sensor is designed and demonstrated for trace detection of benzene, acetylene, and carbon dioxide at ambient conditions. The sensor is based on a distributed feedback quantum cascade laser (DFB-QCL) emitting near 14.84 µm. Tunable diode laser absorption spectroscopy (TDLAS) and a multidimensional linear regression algorithm were employed to enable interference-free measurements of the target species. The laser wavelength was tuned over 673.8–675.1 cm-1 by a sine-wave injection current at 1 kHz repetition rate. Minimum detection limits of 0.22, 5.92, and 8.32 ppm were achieved for benzene, acetylene, and carbon dioxide, respectively. The developed sensor is insensitive to interference from overlapping absorbance spectra, and its performance was demonstrated by measuring the target species in known mixture samples. The sensor can be used to detect tiny leaks of the target species in petrochemical facilities and to monitor air quality in residential and industrial areas.