Simulation And Experimental Research On The Properties Of Waveguide With Periodic Structures

With the continuous development of technology,optical molding technology,laser processing,optical detection,optical fiber sensor and other optical technology used in the mechanical field more and more widespread.On the other hand,with the maturity of micro structure processing technology,preparation of the periodic structure is also developing rapidly.Recently,the optical properties of the periodic structure has aroused great interest to researcher.Theoretical and experimental results showed that if the structure and function of the dielectric constant of the periodic structure material changes in optical wavelength scale,photonic bandgap was existed because of the interaction between the photon and the periodic structure,which has great significance for the fundamental research and practical application.Several kinds of period structure waveguide was in research in sections.Firstly,the typical periodic structure waveguide,fiber grating,was researched.Based on the coupled-mode theory,the parameters affecting the reflection spectrum of FBG,such as the refractive index change induced by UV,the apodization function and the phase shift,were analyzed in detail.Then our research extended to the case that the refractive index gradient along the fiber axis,the properties of the spliced FBG was studied.Based on the properties of the spliced FBG,a novel method to retrieve the parameters of the optical fiber fusion splice was proposed.The effective refractive index profile neff(z),the refractive index change induced by UV ?n0(z),the randam phase shift ?? and the length of the fusion region L0 were retrieved based on an experimental spliced FBG sample,which prove our method is feasible and effective.Secondly,the multimode fiber grating was studied.The coupling coefficient between each mode with different distribution of the refractive index induced by UV were studied,and the corresponding coupled-mode equations are given to analyze the reflection and transmission spectra of the multimode fiber gratings spectrum.A FBG-in-SMS was proposed and researched in detail.The transmission and reflection spectra of FBG-in-SMS are the mixed effects of the interference and FBG,and they were asymmetry.The reflection spectrum of FBG-in-SMS is related to the length of the fiber grating,LFBG,and the location of written-in FBG,L0,and regardless of the length of multimode fiber,LMMF,However,the transmission spectrum is related to the length of the fiber grating,LFBG,and the length of the multimode fiber,LMMF,and regardless of the location of written-in FBG.The temperature responses are similar,even though their spectra are asymmetric.The SMS transmission spectrum shift during FBG written-in process was also presented and explained,a method to tuning the SMS transmission spectrum was proposed.Finally,we also do some research on typical two dimensional periodic structure waveguide-photonic/phononic crystals.Based on the plane wave expansion(PWE)method,a detailed analysis of the structure factor was studied.As the structure factor is related to the geometry only,we presented an efficiency calculating method to impove the PWE method.The efficiency calculating method for the structure factor made the simulation that the structure factor without resolution function possible.Two kinds of low symmetry two dimensional periodic structure waveguide-sector photonic/phononic crystals and "L" shape photonic/phononic crystals were designed and in simulation,and the properties of them were analyzed in detail.