| The rapid development of optical information technology plays an increasingly important strategic role in the modern information transmission.At present,the development of optical information technology is based on There are many kinds of photoelectric elements made of crystal materials.The photonic crystal filter studied in this paper is one of them.Although the current optical devices can meet people’s general daily needs,people’s desire for rapid transmission of optical information does not stop,so it is the current research direction to prepare filters with higher transmission efficiency and smaller size.Photonic crystal materials have their own characteristics,such as photonic band Gap,PBG,when the electromagnetic wave falls within the band gap frequency range,the electromagnetic wave with the same frequency range as the band gap will not be transmitted smoothly,so we can introduce line defects to form waveguides.At the same time,the photonic crystal also has the characteristics of photon localization.The introduction of microcavity can localize the optical signal with a specific frequency to achieve the ideal frequency selection function.Using these characteristics of the photonic crystal,we can To achieve efficient filtering.In this paper,the silicon photonic crystal is taken as the research object,and the circular Si dielectric column is periodically arranged in the air background to form a two-dimensional square lattice photonic crystal filter,which is mainly carried out from the following aspects:1.Based on the research background,the concept,characteristics,common preparation technology,application and research trends at home and abroad of photonic crystals are briefly introduced.2.The basic principles of several research methods of photonic crystal are described.Through comparison,the finite element method is selected for the numerical simulation and analysis design of two-dimensional photonic crystal devices.The band gap characteristics of photonic crystal are analyzed by analogy with electronic band.3.Using COMSOL multiphysics finite element software,the three port download filter of photonic crystal is studied.The radius of microcavity is calculated to be r = 0.068ɑ,and the supported mode is 0.3567 c/ɑ,It is found that the filtering effect without reflection heterojunction can only achieve 34% of the filtering effect,while the filtering effect with reflection heterojunction can achieve more than 90% of the filtering function.4.A multichannel photonic crystal filter is designed,which is composed of four microcavity,one main waveguide,four download waveguides and a large radius Si circular dielectric column embedded at the end(as a reflection heterojunction,100% reflection).The radius of the four coupled microcavity is Ra1=0.0645ɑ,Ra2=0.068ɑ,Ra3=0.0535ɑ,and Ra4=0.059ɑ.The corresponding modes are in the mode range supported by the PC1 line defect waveguide and the forbidden band range of the PC2 line defect waveguide.COMSOL multiphysics finite element software is used for simulation calculation,and the simulation results are plotted by Origin software.The results show that the transmissivity can reach more than 90%,so as to achieve the effect of efficient filtering.At the same time,the influence of heterojunction parameters on filtering performance is analyzed.The results of this paper can provide useful reference for the preparation of PCF and the design of other micro and nano photonic devices,such as optical switch,optical waveguide and so on. |
