Polarization Beam Splitter Based On Silicon-based Photonics Waveguides

In recent years,with the booming development of the Internet,the wide application of artificial intelligence and cloud computing and other technologies,the amount of data in the network has shown explosive growth,and the data traffic will continue to grow at a high speed in the next few years,which has higher requirements for communication bandwidth and rate.Optical communication has become a research hotspot because of its superior characteristics and development potential,and people have given high hopes for optical communication technology.Among them,silicon-based nano-dielectric waveguides are valued by scientists due to their advantages such as high refractive index difference,high integration,compatibility with CMOS process and low cost.Everything has advantages and disadvantages.The high refractive index difference has a high limit on the light,which can reduce the size of the device,but also bring the polarization problem.The polarizati on beam splitter can regulate the polarization state and effectively solve the polarization problem,which is not only a key device in the polarization diversity scheme,but also plays a key role in the polarization reuse communication system.In this pape r,some theoretical research on the design of silicon-based optical waveguide polarization beam splitter,investigated the main implementation scheme of polarization beam splitter,conducted the pattern analysis of silicon-based waveguide.Finally,two new polarization beam splitters are proposed.The main work of this thesis is as follows:(1)This paper analyzes the bottleneck of optical communication,gives the polarization problem of silicon-based optical waveguide,and introduces the workflow of each scheme.We investigated the currently reported polarization beam splitter and classified them to summarize their advantages and disadvantages.Based on the current research results,the published performance of the polarization beam splitter to be improved is analyzed,and the research direction of this paper is determined for the problems to be improved.(2)This paper introduces the basic theory of silicon-based subwavelength grating waveguide,analyzes the structure,and uses the equivalent medium theory.T wo common numerical methods,finite element method and finite difference in time domain,are elaborated.Then,the polarization characteristics of silicon nanowire waveguide and subwavelength grating are analyzed for the performance of the device.(3)We analyze the principle of directional coupler,based on the phase matching method,introduce the grating waveguide into the polarization beam splitter,and propose an asymmetric directional coupling polarization beam splitter based on subwavelength grating.Simulation analyzes the performance of the device,which has a high extinction ratio and a low transmission loss.The device is insensitive to manufacturing errors and still maintains good performance within the process error range of ± 20 nm.(4)Based on the hybrid surface plasma theory,a polarization beam separator with small size and excellent performance is designed.The coupling length of the device is only 4.9 μ m,and its operating bandwidth is 129 nm.The beam splitter is simple in structure,easy to process,and has a high extinction ratio.