Study And Preparation Of Frequency Selective Filters Based On One-dimensional Photonic Crystals

One-dimensional photonic crystal is a structure composed of two or more dielectric materials with different dielectric constants stacked on top of each other during the space period.When the electromagnetic wave is transmitted,it is modulated periodically to form the energy band.If the defect layer is inserted into the photonic crystal,the periodic structure of the photonic crystal will be destroyed and the defect mode will be formed.By artificially controlling the refractive index and thickness of defect layer,the filter at specific wavelength can be realized.In this paper,one-dimensional photonic crystal is taken as the research object,and the main research contents are summarized as follows:1.The energy band and transmission characteristics of one-dimensional photonic crystals are calculated based on the transfer matrix method,and then the reflection characteristics of periodic photonic crystals are analyzed by changing the number of periods in the one-dimensional photonic crystal structure,the refractive index ratio of dielectric materials and the incidence Angle of electromagnetic waves.In addition,the influence of optical thickness and refractive index of defect layer in periodic one-dimensional photonic crystal on filtering characteristics is also summarized after the insertion of defect layer,and a one-dimensional photonic crystal structure that can accurately control the location of defect mode is designed.2.Preparation method based on the results of simulation by electron beam evaporationSi-Al ₂ O₃ one-dimensional photonic crystals,first discuss the effect of ion source assisted deposition in electron beam evaporation and the film forming mechanism of electron beam evaporation,and the process and principle of elliptic partial instrument measuring film thickness is analyzed,finally prepared three different center wavelength of a one-dimensional photonic crystal structure,the preparation of the samples in line with the simulation calculation results,the position of defect modes as the change of center wavelength and mobile,and using two materials to conduct a film thickness comparison experiment,then we summarized the reasons why electron beam evaporation affects the uniformity in the repeated coating process:the pits caused by the thermal conductivity of the material will cause the uniformity of the coating to decrease sharply,and greater pit depth results in worse uniformity...