Study Of The Method For Multiplexing Fiber Optic Fabry-perot Sensors Based On Frequency-shifted Interferometry

Fiber Fabry-Perot (F-P) sensor is a kind of commonly used and extremelyimportant Phase modulation sensors, which uses the principle of dual-beaminterferometry to detect the measured quantities. Because of its production of simple,small sensing area, high sensitivity, F-P sensors have been widely used in the fieldsof construction, aerospace, biomedicine, composites and other fields, especially in thefield of smart structures. The multiplexing of fiber F-P sensors is an obstacle inrealizing its large-scale application and has become one of current research focuses.Firstly, the principle and demodulation techniques of F-P sensors are brieflyintroduced, and a new Multiplexing method based on Frequency-Shifted are proposed.This thesis analyzed detailedly the principles of Frequency-Shifted techniques and itsapplication on F–P sensors multiplexing. A theory model of sensors multiplexing waspresented according to theoretical analysis. With the existing conditions in thelaboratory, we designed a multiplexing system to demodulate a fiber F-P sensor array.A Labview program was developed to control the hardware and process theacquisition data. In the experiments, we obtained the reflectance spectrum and thelocation of all fiber F-P sensors within a certain spectral width in differentstructures. Multiplexing system for temperature and strain sensing characteristics ofF-P sensors were studied experimentally with bimodal demodulation method, whichfurther confirmed the effectiveness of the new multiplexing method in this paper.Finally, the problems and improvements of the demodulation systems were analyzed.