The Research Of Wavelength Interrogation Method About Distributed Feedback Fiber Lasers (DFB-FL)

Since the 1990s, as one of important development in the field of fiber lasers, the Distributed feedback fiber laser (DFB-FL) has been widely used in optical fiber communication and fiber sensing, especially in fiber-optic hydrophone, because of its obvious characteristics, such as ultra-narrow line width, high sensitivity, large dynamic range, easily multiplexing capability, and so on. More and more researchers began to study and explore DFB-FL, at the same time the DFB-FL wavelength interrogation has become a research hotspot.This article introduces the fiber laser, especially the development process and prospects of the DFB-FL. The analysis of DFB-FL sensor working principle and the wavelength interrogation were presented in the paper. A phase generated carrier (PGC) interrogation system based on unbalance M-Z fiber interferometer was constructed, and a new interrogation method, which was based on the gas absorption peak wavelength interrogation, was offered in this paper, its feasibility was verified from theory to experiment. Main work and innovations of the paper is summarized as follows:1. Reviewed the production, development, and application prospects of the fiber laser, especially in DFB-FL, in particular the application as fiber-optic hydrophone,; introduced several common wavelength interrogation methods, and presented some wavelength interrogation methods suited to DFB-FL.2. Briefly introduced the basic theory of optical fiber lasers; specific analysis of the DFB-FL work principle and its every components characteristics and working principle, included phase-shift grating, pump circuit design and debugging, selection of optical devices; then analyzed the DFB-FL strain sensing characteristics theoretically.3. Presented the DFB-FL sensor interrogation principle, highlighted the phase generated carrier interrogation method based on the unbalanced M-Z interferometer, and designed an unbalanced M-Z fiber interferometer interrogation system, a series of experiments were made using speakers as a sound sources; then analyzed the experimental results; at last build voice recording system with this system, and got good results.4. Proposed a new wavelength interrogation method, which is based on the gas absorption peak, it is the first time presenting this wavelength interrogation method, and design a simple interrogation system taking the acetylene gas for example, carried out related theories and experiments to verify the feasibility of the method, and discusses some ideas about the extensions to the dynamic range, improving the sensitivity...