Fiber Grating Spectral Response Characteristics Of The Measurement Of Transient Strain

Because of many excellent features, fiber grating sensors are used in wider areas. More and more people pay attention to them. This paper mainly studied: the theory of the responses of fiber Bragg grating affected by homogeneous strain, non-homogeneous strain and transient strain.1. The transmission theory of the fiber grating is analyzed by using the coupled-mode theory, and the response characteristics of fiber Bragg grating are studied by programming using the transfer matrix method. We analyze the relations between the refractive index modulation depth Aw and the spectrum characteristics of fiber grating with the same length. We can conclude that: the bandwidth, the center wavelength and the reflection rate of the reflection spectrum will be greater with a greater△n.2. We further analyze the response characteristics of fiber Bragg grating affected by homogeneous strain, with the gradual increase of the homogeneous strain, the bandwidth, center wavelength and the reflection rate of the spectrum becomes larger, we can get specific values from the numerical-calculated maps. Then we analyze the non-homogeneous strain which we have assumed as a Gaussian shape, in the reflection spectrum, there are a lot of different center wavelengths, and the bandwidth is broad, the shape of spectrum is not a regular one.3. We go on study the impact of transient strain on the response of FBG. We consider it like this: we divide the whole transient process into several points, and each point represents a moment the transient strain in fiber grating. Then we analyze the corresponding spectrum characteristics of FBG, so we can get the changes of the spectrum in the whole process. The study is particularly important for analyzing the testing result of transient strain, using the non-equilibrium optical M-Z interferometer demodulation system. The content is the basic theory research of testing the transient strain in the barrel.4. We carried testing transient experiments on artillery, using the non-equilibrium M-Z interferometer demodulation system, and obtained the strain of changing amplitude and width. We get very important results from the testing, laying a good foundation for the further testing work of transient in the barrel.