The Bragg Fiber Transmission Characteristics Of Theoretical Analysis And Simulation

As a one dimension photonic crystal fiber, Bragg fiber is based on the photonic bandgap guiding mechanism. Compared with conventional fiber, Bragg fiber can lead to lower propagation loss and improve the threshold for nonlinear effects. Moreover, Bragg fiber has a number of independent structure parameters, which improve the controlability of the fiber's dispersion properties. Recently, Bragg fiber has been attracting more and more attention of scientists from national and abroad. The application of Bragg fber is extending towards various fields such as communication, surgery and sesor. Especially with the development of computer capacity, finite different time domain method and finite element method are used to deal with more complicated fiber structures, which will deepen and complete the analysis of Bragg fiber.A systematic research is made by using the transfer matrix method and asymptotic matrix method. By discussing the effect of each structure parameter, dispersion and loss properties are analyzed and a comparably complete Bragg fiber theory is established. This theory provides a foundation for the manufacture and application of Bragg fiber. This thesis is composed of four parts:1.Bragg fiber's dispersion and loss properties are discussed using asymptotic matrix method. In a specific wavelength, the cladding index contrast, core radius and core index are altered to optimize the transfer properties.2. Electromagnetic fields for both radiation and guided modes are widely discussed by considering the cladding field. The classification standard of guide mode and radiation mode are analyzed. Furthermore,the problem that how Bragg fiber's structure parameters affect the guide mode area is researched.3.The mode shape and dispersion coefficient of large core single mode Bragg fiber are discussed. the design of a narrow band filter for single wavelength at a single angle of incidence is similar to the design of this single mode Bragg fiber.4.In order to analyze more complicated Bragg fiber structures, three methods, asymptotic matrix method, transfer matrix method and Galerkin method are compared and discussed. The last two methods are proved to be more convenient in studying aperiodic fiber and disturbed periodic fiber.