Fiber optic methane sensing system based on temperature-tunable distributed feedback laser

A fiber optic methane sensing system based on the temperature-tunable distributed feedback (DFB) laser is experimentally demonstrated. Two laser diodes (LDs) with different wavelengths are used in the system. One LD operates in the wavelength scanning mode, and the other LD is used as the reference beam to eliminate the fluctuation of light intensity. By comparing the intensities of the two wavelengths during wavelength scanning, we can determine methane content. Experimental results show that a measurement resolution of 0.038% can be reached. The obtained measuring system has good properties of high precision, low cost, and high reliability.