Research On The Improvement Of Silicon-based Optical Waveguide And The Mechanism Of Surface Smoothing

At present,with the development of electronic information technology and the rise of the Internet applications,the traditional semiconductor materials and manufacturing processes are unable to satisfy the integration requirement and the performance indicators of the chip.The generation and development of silicon photonics provide the possibility of the appearance and application of the optoelectronic integrated circuit.The silicon-based optical waveguide is a new kind of waveguide device based on the transmission characteristics of the evanescent field to achieve optical coupling and interconnection in nanometer scale.It is gradually taking the place of the traditional photoelectric components and becoming the good carrier of the integrated optoelectronic devices with high speed,high efficiency and high density because of its quantum size effect,surface effect,quantum tunneling effect,and the compatibility with the CMOS process,which is the foundation of the integrated photovoltaic system with large capacity,high integration and high processing speed.However,the development of the nanometer optical waveguide device isstill being on the groping phase,and there are many basic science issues and key technologies needed to be solved.The intensity of the output signal of the waveguide is one of the important problems to the application of the nanometer optical waveguide technology.The intensity of the waveguide output signal is mainly affected by two factors: the coupling efficiency and the transmission loss of the optical waveguide.Based on above,the nanometer optical waveguide is regarded as the research object in the thesis.On the one hand,the coupling mechanism of the grating was analyzed theoretically to improve the coupling efficiency of the waveguide.The parameters of the incident light and grating structure were analyzed systematically.The grating coupler with high coupling efficiency was designed on the basis of the theoretical analysis and structure optimization.The optimized coupling efficiency was 59.37% and the 3dB bandwidth was up to65 nm.The coupling efficiency of the optical waveguide was improved theoretically,which can effectively enhance the intensity of the output signal of the waveguide.On the other hand,the relationship between the surface roughness and the transmisssion loss was analyzed,in order to reduce the transmisssion loss of the waveguide,which provided the theoretical support for the establishment of the reaction model of the waveguide surface.The micro-mechanism of the silicon-based waveguide surface smoothing in hydrogen annealing is investigated systematically to illuminate the effect of silicon-hydrogen bond onthe surface smoothing in high temperature hydrogen annealing.Furthermore,the experimental validation of hydrogen annealing was conducted,which provided the theoretical and experimental foundation for reducing the transmisssion loss in the surface treatment process of the optical waveguide device.