Research On Slow Light Characteristics Based On Photonic Crystal Waveguide

The all-optical network is a trend of future communication development.Among them,optical buffering is an important link in realizing wireless communication all-optical networks,and the emergence of slow-optical technology provides a new method and idea for the implementation of optical buffering.The best way to obtain slow light is the photonic crystal waveguide structure.As a brand-new optical element,photonic crystals have the advantages of flexible structure,small size,easy integration,and can exhibit various optical properties under different structures.In addition,it has great potential in achieving wide bandwidth,making photonic crystals better adapted to future high-speed communication technologies.In order to obtain a photonic crystal waveguide structure with wide bandwidth,high delay and low group velocity dispersion and slow light characteristics,this thesis has carried out in-depth research:The main contents are as follows:First,the design of the photonic crystal line-defect waveguide is completed,and the wider band gap structure is obtained by rotating the square lattice structure counterclockwise 45 degrees to get the new lattice structure,the slow light characteristic parameters are optimized by introducing an extrinsic defect in the central row and the second row adjacent to it.After determining the lattice structure and introducing the line defect location,the slow light characteristics are enhanced by dynamic adjustment of the structure parameters,and the numerical calculation is carried out by combining the plane wave expansion method with supercell algorithm,the experimental results show that the slow light bandwidth reaches 23.37 nm,the group velocity reaches 26.16,and the NDBP value reaches 0.3944.In order to further optimize the slow-light performance of line-defect waveguide,the influence of the material properties on the slow-light performance is analyzed by changing the index of refraction of the dielectric cylinder where the non-intrinsic defects are introduced.The maximum NDBP is 0.4427,at the same time,the value of group velocity dispersion is within the range of no distortion in the optical transmission.Compared with the best result obtained from the analysis of structure parameters,the slow light characteristic is further improved.Secondly,the slow light characteristics of the coupled-cavity waveguide are analyzed.By rotating the square lattice 45 degrees counterclockwise,a new lattice structure is formed by alternating rows and rows of dielectric cylinders with Radii of and respectively.The structure of photonic crystal coupled-cavity waveguide is formed by introducing a point defect in the central line.The slow light parameters of the waveguide structure are optimized according to the distance between the coupled-cavity.The maximum NDBP is 0.3313,with the increase of the coupling cavity spacing,the bandwidth decreases and the delay increases.It can be concluded that the delay increases at the expense of the bandwidth.Based on this analysis,a new type of coupled-cavity waveguide structure is proposed,and its radius parameters and coupled-cavity translation are analyzed to optimize the slow-light characteristics.