Research On Coupling Technology Of Integrated Optical Waveguide

With the development of integrated optical waveguide devices that achieve specific functions in recent decades,it has become the main driving force for the rapid development of the optical communication industry.However,there are many technical branches of optical waveguide devices with different structures and forms.Inconsistent technical standards lead to bottlenecks such as huge mode field mismatch and poor compatibility when optically interconnecting heterogeneous optical waveguide devices.The key to solving this problem is high-efficiency integrated optical waveguide coupling technology.The theoretical basis of the integrated optical waveguide coupling technology is mainly strictly coupled wave theory.The initial design of the coupling grating in this paper is based on this theory.After the preliminary design is completed,the FDTD numerical analysis method is used to simulate and optimize it.Waveguide coupling device substrate materials mainly include indium phosphide,silicon nitride,silicon-based,etc.At present,the mainstream is based on silicon-based,typical coupling devices are grating couplers,optical filters,optical beam splitters and so on.The work of this paper is mainly dedicated to the research of integrated optical waveguide coupling technology to solve the technical problems of low coupling efficiency and difficult coupling of optical waveguide devices.The research method is:Based on the optical waveguide coupling theory,the coupling conditions of grating coupling devices are studied and the coupling model is established.Based on the model,the relationship between the typical structural parameters of the optical waveguide coupling device and the coupling efficiency transfer is analyzed,and the simulation calculation is used to optimize and design the output.In this paper,the grating-coupler based on the SOI?Silicon-On-Insulator?structure is selected as the main research object.The main tasks include:?1?Relevant derivations and coupling models were established based on the Bragg condition and strict coupled wave theory in design theory,providing theoretical model basis for subsequent parameter analysis;the principles and performance of the beam propagation methods BMP and FDTD algorithms based on numerical calculation The comparative analysis is carried out,and the FDTD numerical calculation method is used as a technical tool for subsequent simulation experiments.The technical characteristics of the particle swarm optimization algorithm and the accompanying optimization algorithm used in the design of this paper in the optimization design are discussed.?2?Based on the key parameter analysis and related derivation in the coupling model,the transfer relationship of coupling grating waveguide layer height,grating period,SiO₂ layer thickness,incident angle,reflection layer thickness and position on coupling efficiency were obtained;The correlation between the core parameters and the coupling efficiency and the range of values were verified.Based on the correlation results,the optimal design parameter values in each structure were obtained.?3?A large bandwidth and high efficiency grating coupler is designed.Based on the previous theoretical research results,the three-layer structure of the Bragg reflector layer?Si/SiO₂/Si?is designed on the SiO₂ layer to achieve efficient coupling.Through the optimization of structural position and simulation of the accompanying optimization algorithm,a large bandwidth and high efficiency grating is completed Detailed design and parameter optimization of the coupler.The device performance is:for TE0polarized light with an incident wavelength of 1550nm,its coupling efficiency is 61%,and the-3dB bandwidth is 81nm.After the optimization model is completed,the silicon material in the waveguide layer of the model is replaced with silicon nitride?Si₃N₄?and indium phosphide?InP?materials.After optimization,the coupling efficiency curve is extracted,proving that silicon nitride is used as the waveguide layer material feasibility.?4?Introduce the manufacturing process of Si-based devices and analyze the influence of the grating error brought by the main processing technology in the lithography process on the coupling efficiency,simulate and analyze the coupling efficiency degradation caused by process errors;simultaneously,the relationship between fiber alignment error and coupling efficiency is simulated and the principle of priority in coupling is obtained.