[Application of correlation spectroscopy method to fiber gas sensor].

In this paper, we employ correlation spectroscopy method to detect gases and gas mixtures which have multi-line absorption in near infrared. The theories of correlation spectroscopy are discussed and a new modulation measure is proposed, which inherits the excellence of the correlation spectroscopy and makes the modulation easy. Then we compare this method with the traditional correlation spectroscopy method. Experimental results for the selective detection of methane by this method are also presented. The change in signal from interference gas is only equal to 7.4% of that from methane absorption. It has been proven that the proposed method is practicable for both theory and experiment. This method can reach a high accuracy for mixed gas detection.