Study of optical fiber carbon monoxide gas sensor with DFB LD

Based on the near-infrared absorption theory, a new carbon monoxide concentration measurement system is devised. The near-infrared absorption line of carbon monoxide is chosen as the measured spectrum and a distributed feed-back laser diode (DFBLD) is used as the light source. The wavelength of the light source is locked at the carbon monoxide gas absorptive peak which is chosen at 1.567μm by light source modulation technology, and the signals are processed by lock-in amplifier. The ratio of the second-harmonic to fundamental signal is used as the output of the system to eliminate optical interference. Optical fiber is used as transmission medium, instead of traditional complex optical system, so the structure of the system would become miniaturization. Proved by examinations, high measurement sensitivity of carbon monoxide gas can be achieved in this study.