Fiber Grating Sensor Network Technology Research And Applications

Fiber gratings are attracting considerable interests in applications. They are new type of passive optical components, which are based on the periodical distribution of refraction index in fiber core. Fiber gratings have several distinguished advantages over normal fibers. Because of their intrinsic nature and inherent wavelength-encoded operation, fiber gratings are utilized as sensing elements in recent years. The relevant reports have been appealed much attention throughout the world.Encoding the information on the measurand in a wavelength form has been caused extensively focus. The most important advantage is that wavelength is an absolute parameter and thus does not depend on loss of the system or fluctuation of the source power. Most of today's demodulation techniques rely on optical filtering method, such as bulk optical edge filters, scanning fiber Fabry-Perot filters, WDM fiber couplers, acousto-optic tunable filters and Mach-Zehnder filters.In this report, we mainly focus on the research and realization of fiber Bragg grating networks, including the principles and experiments of sensing and demodulation techniques. The contents are listed as follows:1. Generally introduce the sensing technique, especially the present situation and development of fiber and fiber Bragg grating sensor technique. The fundamental theory of fiber grating is also demonstrated. The basic principle of fiber Bragg grating sensor and demodulation and multiplex technique can be found in this dissertation.2. Using the fiber grating as the basic sensor unit, we design several kinds of FBG sensors which are suitable for application. Moreover, the design principle, the system structure as well as the test results are demonstrated in detail.3. We designed and realized a high-speed sensor multiplexing network system based on the F-P tunabled filter. The high-speed wavelength demodulation of fiber Bragg grating sensor has been turned into practice. The system principle is introduced and analyzed in this dissertation. The system is designed as an all-fiber system. It realized the high-speed wavelength-division-multiplexing demodulation of fiber grating sensor. 4. Some theorical works on tilted fiber Brag grating is presented in this paper. And more, we firstly build the demodulation system based on TFBG in the world. The principle and structure are introduced in detail. And the experimental results are also presented.5. In this report, a power-equilibrium tunable C+L band Erbium-doped fiber lasers is proposed and demonstrated. The laser is based on Erbium-doped fiber ring, and a F-P filter incorporated with a tunable bandpass filter in the ring. At the same time, the Auto-Power-Control (APC) technique is used to proportion the output power of the laser. The laser has wide tunable range from 1525nm to 1612nm, and the sidemode suppression ratio is more than 55dB. The output power variation is less than +/-0.1dB over the running range.6. At the end, we discuss the feasible techniques for fiber fence. Using M-Z interferometer, we build and realize a practical fiber fence system. The principle and structure and also the experimental results are presented and discussed.