Carbon Monoxide Gas Sensor Based on Cavity Enhanced Absorption Spectroscopy and Harmonic Detection

A fiber carbon monoxide gas sensor was reported in this paper. Due to CO has a much weaker absorption in near infrared region, the harmonic detection technique is combined with cavity enhanced absorption spectroscopy (CEAS). The basic principle of harmonic detection technique and cavity enhanced absorption spectroscopy are expatiated at first. We designed the experiment scheme and analyzed the key problem in the experiment. The second harmonic signals were extracted at different CO concentration and we fit the amplitude of the second harmonic and corresponding CO concentration. The experiment results indicated that the amplitude of second harmonic and CO concentration have a good linearity relationship. A sensitivity of about 10 ppm has been achieved with this measurement.