| Optical fiber grating is a kind of optical fiber passive device, it has been developed quickly and widely used in recent years. It has great application prospective in optical fiber communication and optical sensor field and so on for it's many unique merits. Optical fiber grating sensors based on optical fiber grating technology have become the focus in sensors study field. It's predominant merits in sensors is multiplexing use. A sensor net can be composed by using many optical fiber gratings. It can be applied in detecting many sensor points especially in intelligent and smart structure. Our main research work is as follows: 1 Theory analysis of fiber Bragg gratings(FBG) are presented including the coupled-mode theory used in fiber grating, the propagation characteristics of light wave in FBG, the physics characteristics of FBG, optical fiber grating sensor mechanism. the developments and application of fiber grating sensors are presented. 2 Several typical demodulation filter methods using in optical fiber sensor have been developed are presented and discussed, and we studied the matched-grating demodulation technology theoretically and experimentally, wavelength resolution of 2.33pm is obtained. 3 A novel combined wavelength-and-time-division multiplexing operation by using a tunable fiber laser was demonstrated successfully at first in the reported document about multiplexing sensor system. The system has high signal-to-noise ratio and can multiplex a large number of FBGs, which can be economical and practical in sensor array system. Our main research work is as follows, (1) We designed a tunable fiber laser used as the source of optical sensor system whose tunable wavelength is 10nm, and analyzed it's operating principle. (2) We modulated the fiber laser output to light-pulse used for time multiplexing by using a chip microcomputer and a optical intensity modulator, compared to the common BBS, which has a high peak power and high signal-to-noise ratio after using in sensor net.
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