Research On The Array Technology Of Fiber Grating Sensors

Today, our society has gone into an age of information. Being another information carrier, photon is playing an important role gradually. Optical fiber has been widely used as the most important transmission medium in the telecommunication networks. Various optical fiber devices and systems have been developed, which greatly enhance the flexibility of the network. Fiber gratings are being considered as a landmark and attracting considerable interests in applications, 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 such detection fields as stress﹑temperature﹑pressure﹑electric current﹑voltage﹑vibration and so on. 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 dissertation, we mainly focus on the research and realization of fiber Bragg grating networks, including the principles and experiments of sensing and demodulation techniques. The main contents are listed as follows:1.Generally introduce the present situation and development of fiber sensing technique and fiber grating sensing technique. The fundamental theory of fiber grating and its fabrication method are also analyzed. The basic principle of fiber Bragg grating sensor and demodulation and multiplex technique can be found in this dissertation.2. The characteristics of FBG have been studied by means of the coupled-mode theory. Reflectivity﹑center wavelength and 3dB bandwidth of several types of fiber grating, such as uniform period FBG, long period fiber grating have been deduced. Moreover, the network principle about fiber sensor and fiber grating sensor has been described, in which the limitation of sensing pots in a network has also been given.3.In order to make clear of the key points of FBG sensing technique, the method of...