Research On Optical Fiber Grating Sensor

It has been 30 years from the appearance of optical fiber grating, the fiber grating is made up on the fiber's photosensitivity, using ultraviolet light to exposure on the fiber result that the refractive index in the fiber core is changed, thus, a new type of fiber passive device come up. Fiber grating is similar with a narrowband filter or a reflector. When the outside circumstance changes, the Bragg center wavelength will produce a shift because of the thermo-optic effect, elasto-optic effect, and Faraday effect etc. We can get the change of outside temperature, stress and magnetic field by measuring the wavelength's shift. By this way, many physical parameters can be measured, such as acceleration, libration, concentration, liquid level, current, voltage etc. According to this speciality, the fiber sensor and fiber sensor network for multi-parameter measuring are produced continuously. Along with the continuous perfection of fiber grating read-in and packaging techniques, some fiber grating sensors have been produced on a wide scale.Apart from the fiber's natural advantages, such as lightweight, small diameter, flexible, chemical stability, high temperature, anti-electromagnetic interference etc, fiber grating sensor also has many unique advantages, such as small size, easy-buried in structure, multi-using, easy-formed networks, quasi-distributed measurement, high sensitivity, fast response, long transmission distance, and because the measurement information is encoded at the absolute wavelength measurement, it escape from the influence of the light intensity fluctuations, fiber connection loss and coupling loss, and changes of light polarization state, therefore, fiber grating sensor has stronger anti-interference capability. All these advantages make fiber grating sensor an ideal sensor, which has been widely applied in aerospace, navigation and other military areas, large civil engineering, electric power, medical care, and other civilian areas. More and more increasing application shows that the fiber grating has become the most promising and representative one of the optical passive devices.In this paper, for the purpose of studying the fiber grating theory and its sensing applications, I've done the following work. First, outlining the history of fiber grating sensing technology and the actuality of its research and application; introducing fiber photosensitivity and fiber grating read-in methods, studying fiber grating model theory. Second, introducing fiber grating packaging and photosensitivity technology, on this basis, giving a new packaging structure of temperature sensor. Next, working on fiber Bragg grating sensing technology for the theoretical research and experimental analysis, theoretically and experimentally, proving that fiber Bragg grating has good temperature sensing characteristics. Finally, introducing several fiber grating sensing demodulation methods, and presenting a new demodulation method with sensor selection and circuit design.Through the theoretical study and experimental analysis, we can find that fiber grating sensor has many unique advantages compared with traditional mechanical and electrical sensors. At present, most research focus on the technology of fiber grating's packaging, photosensitivity and signal demodulation, it has great significance to design fiber grating sensor with high-performance and long-life, and signal demodulator with high sensitivity and multi-channel. With practical applications, to make the fiber grating sensor be applied widely from laboratory to practical engineering, the major work is to speed up the theoretical research and laboratory development.