Application Characteristic Research Of Sampled Fiber Grating In Sensor And Comb Filter

At present the theory and fabrication of fiber gratings is growing, its application is more and more widely, more and more attract people’s attention. Sampled grating is a new kind of optical fiber grating, it has many advantages, such as low insertion loss, passive, weak polarization dependent, flexible and other advantages, excited great interest and enthusiasm of people in many fields.This paper introduced the basic theory of sampling grating and the fabrication technology at first, and analyzed the reflection spectrum by transfer matrix method, and through simulation experiment to get the effect of the sampling grating parameters changes to reflecting spectrum of the fiber grating.Changes of temperature and strain impacted on the sampling grating reflection spectrum at the same time, reflectivity and wavelength of the reflection spectrum will change at the same time when temperature and strain changed. Using this characteristic of sampling grating, we can measure the temperature and strain. This paper constructed a suitable sampled gratings, obtained its sensing characteristics data through simulation experiment, and got4parameters (A, B, C, D) of its sensing characteristics matrix, arrived at the functional relationship about reflectivity and wavelength drift with temperature and strain changes of sampled grating. Achieved at using a single fiber grating to measure the temperature and strain at the same time.Then through the method of changing parameters of sampling grating to simulate the reflection spectrum, and debuged several optical comb filter based on sampled grating. At the same time, proposed using empirical mode decomposition (EMD) method for filtering analysis and noise reduction to optimize the reflection spectrum and time delay spectrum of the optical comb filter. The principle of empirical mode decomposition method is decomposing the original signal into several intrinsic mode functions, and divided this intrinsic mode functions into two types, they are the modes dominated by signal components and the modes dominated by noise components, and then removed the modes which noise component plays a dominant role in, to reconstruct the signal by the mode reflected main structure of the signal, thus to achieve denoising.