Fbg Strain Sensor Demodulation Techniques

With the rapid development of technology in the field of optical fiber communication and optical fiber sensor (OFS), more and more researches and applications with optical fiber sensors are applied in recent years, as one of novel interrogation systems. Compared to traditional electric transducers, the optical fiber sensor takes optical signals as vehicle for modify and transportation, with advantages of small size, light weight, and anti-electromagnetic interference; meanwhile, OFS can adapt to work under special situations like flammable and combustible medium. Not only these advantages which common OFS has, does fiber Bragg grating (FBG) sensor have, but also fiber grating sensor will not be influenced by the fluctuation of the laser source, the loss of fiber bending and connection for its wavelength encoding. Furthermore, FBG sensor can be monitored for its structural integrity, security, and injury severity in real-time, because of its self-reference, without the need of inherent fiducial point. It is possible for FBG to make the fiber grating sensor array distributed come true as well, by the usage of dense wavelength division multiplexing (DWDM). Generally, FBG will have large worth in the fields of civil engineering, space flight and aviation, and chemical engineering.This research paper focuses on the theory and application of FBG. It introduced the structure of FBG and researched for the characteristic of strain sensitivity as well. Further, theoretical simulation on the shift of reflective spectrum of FBG under strain had been conducted after the reflective expression of FBG had been formulated according to the coupled-mode theory.Moreover, this research discusses both the advantages and disadvantages of different types of package, and introduces the operation process in details, which is selected. We demonstrated varieties of FBG static strain sensor devices and calculation formulas, forming the experimental system of structure. We collected data with spectrum, given by optical sensing analyzer (OSA). Two sets of cantilever beam were set up and analyzed for the sensitivity of the strain under the current conditions. In conclusion, strain detected by cantilever beam setup with FBG is in good statement of relatively linear.FBG strain sensing, which is based on intensity-demodulated is figured out through the research of spectrum. By selecting both laser source and FBG decently, the amplitude of dynamic strain is in linear with the intensity of output signal. Then, the observation is conducted after setting up the experimental system according to the theoretical analysis. Last but not least, the research also involved Mach Zehnder interference system of the transportation through optical fiber. The principal and fundamental structure of Mach-Zehnder interference system was presented as well. The discussion of result is holden after setting up the experimental system and conducting observations.