Research On Refractive Characteristic Based On Two-dimensional Photonic Crystal And Its Application

In recent years,as a new artificial material,photonic crystal has attracted more and more attention of researchers for its incomparable properties and broad application prospects.The negative refraction materials have many novel properties,so this field has attracted great attention in optics,materials engineering and microelectronics.The negative refraction based on photonic crystal not only has all the advantages of negative refraction materials,but also extends the operating frequency to the light band,when compared to the traditional negative refraction.At present,the negative refraction of photonic crystals is mainly divided into positive-negative refraction effects and dual-negative refraction effects.Although the theory of negative refraction in photonic crystals has been mature,the study of positive-negative refraction and dual-negative refraction is still in the early stage.Thus,this thesis presents two different structure of two-dimensional photonic crystal,on the basis of theoretical analysis,after the simulation with the method of finite-difference time-domain,we can finally realize positive-negative refraction phenomenon and more obvious dual-negative refraction phenomenon,and analyze it.Finally we explore its related applications.The main achievements and conclusions are listed as follows:(1)The structure of a two-dimensional photonic crystal with square lattices is designed,and an anti-reflection layer is introduced on the surface to increase the transmittance,then the positive-negative refraction is realized.The band structure and the equal frequency contour(EFC)are obtained by plane wave expansion(PWE)method.The influence of photonic crystal structure parameters on the normalized frequency and bandwidth of positive-negative refraction effects is studied by photon band structure and equal frequency contour.Finally,the optical beam splitter is realized by the positive-negative refractive characteristics of the structure,and the influence of the incident angle and the incident frequency on its performance is studied.(2)The structure of a two-dimensional photonic crystal with hexagonal lattices is designed,and an anti-reflection layer is introduced on the surface to increase the transmittance,then the dual-negative refraction is realized.The band structure and the equal frequency contour are obtained by plane wave expansion method.Simulation though time domain finite difference method(FDTD)is carried out to verify whether the simulation result agrees with the theoretical value.Next,the performance of the dual-negative refraction is studied.The influence of the incident angle,the radius of the transition column,the incident frequency and the photonic crystal structure parameterson the dual-negative refraction effect is analyzed.Finally,the dual imaging effect is achieved by the dual-negative refraction characteristic of the structure,and the optimum effect is obtained by changing the thickness of the dielectric layer.