Study On Fiber Grating Sensor Based On OFDR Multiplex Technique

Fiber Bragg grating(FBG) is a new type of passive optical components which has been developed quickly in recently years. It has been greatly applied in optical fiber communication and optical sensors for its unique merit. As a sensing element, Fiber grating's distinguished advantage is that it can realize distributed sensing by the multiplex techniques, therefore, lots of researchers are interested in fiber grating sensing demodulation and multiplex techniques.In this dissertation, we analyze the strain and temperature sensing principle of FBG, generally introduce several demodulation and multiplex techniques of fiber grating, a distributed FBG sensing network system that combines tunable F-P filter and optical frequency domain reflectometry (OFDR) is put forward.We construct a demodulator using fiber tunable F-P filter as a core element, make-up a OFDR multiplex system which is consist of triangle generator, voltage controlled oscillator(VCO), light intensity modulator, multiplier and frequency analyzer. Micro-active instrument and electric-heated thermostatic tanker are used to simulate external signal of strain and temperature, though FBG strain and temperature demodulation experiment, we inquiry the address of 3×3sensing matrix, realize the distributed FBG sensing network, due to the effect of external temperature, a temperature compensation is designed. In order to be more accuracy and smarter, a improved system is put forward.