Research On Signal Source Of Dual-loop Multi-point Optical Fiber Methane Gas Sensor

With the advantages of high sensitivity, wide bandwidth, easy integration, optical fiber gas sensor can work in the bad environment and has been drawing more and more researchers' attention. Placing gas chamber (measuring point) in DLOB, an optical fiber methane gas sensing system is designed which based on spectrum absorption methods to detect multi-point methane gas concentration by dual-wavelength in single optical path. In terms of system flow-process, the mathematical relationship is deduced by analogy with two measuring point, which shows the connection between fiber length and data width of signal source, and the relationship between control optical pulse width and signal optical pulse width. Considering optical fiber length, structural system is built on the basis of the principle. In this paper, driver circuit of DFB LD is designed to achieve the direct current (DC) driving and temperature monitoring. Furthermore, according to frame format of signal source, the alternating current (AC) signal is modulated by programming with CPLD.