Optical Fiber Gas Correlation Spectroscopy Detection

Fiber optic sensor came up with the development of fiber optic and optic communication, which is a new technology since 1970s. Fiber optic gas sensor is a novel sensor which takes advantage of the attenuation of optic power when transmitting through the medium.In this dissertation we discussed the theories and characteristics of the fiber optic gas sensor, analyzed the developments of various optical fiber gas sensor. We present a novel method with broadband source and comb filter. This method is especially good at detecting gas with comb absorption peak in near-infrared spectrum, such as methane and acetylene. We also adopt the method of correlation spectroscopy in signal process. At last we select optical components and build up this system, then debug it.According our understanding of correlation spectroscopy, we put forward a new modulating measure, which inherits the excellence of the correlation spectroscopy and makes the modulation easy. We have proved our measure practicable both in theory and experiment.We present a comb fiber optic filter by a high-birefringence (Hi-Bi) fiber, which match the multi absorption peak . So the sensitivity of our system has improved.Some favorable results were also got after experiment, which prove our system is in good performance and has a simple framework. The experiment results have great agreements with the theory result. Aiming at the difficulty of cross talking in designing a gas sensor, we have a breakthrough in solving it.