Research On Board-level Optoelectronic Interconnection Technology Based On Optical Waveguide

In the trend of the information technology revolution in the 21st century,the development of electronic information technology can be a byword.The electronic system seems to continue to break through the limits of high speed,high density,and miniaturization,but the physical characteristics of the electrical interconnection wire are difficult to change.As the speed and frequency increase,the parasitic effects in electrical interconnects become more severe.Even though the placement and routing can be optimized and the transmission path can be shortened to improve its performance,it cannot fundamentally lift the restrictions on the development of high-speed communications systems.As a promising alternative to electrical interconnects,optoelectronic interconnect technology has attracted the attention of more and more researchers.Photovoltaic PCBs with light guide layers implanted on substrates will be an inevitable trend for PCB development in the future.In this thesis,the key components and technologies involved in the waveguide-embedded board-level optoelectronic interconnects are studied,and the following work is mainly completed:?1?For the transmission layer,optical waveguide,simulation analysis for process defects and preparation on FR4 substrate are conducted.Firstly,based on the ray and electromagnetic theory of the optical waveguide,the effects of process defects such as sidewall roughness and steepness on the distribution of the light field are simulated and analyzed.Then,a multi-channel polymer optical waveguide was fabricated on the FR4substrate by developing and etching technology,and the process and parameters were described in detail.After the preparation,the top surface and side surfaces of the optical waveguide were tested for roughness using a 3D measuring laser microscope.The top surface roughness was 12 nm and the side roughness was 58 nm.The results were within the process tolerance range.Finally,a pass light test was conducted.When the laser wavelength was 850 nm,the transmission loss of the optical waveguide was 0.24 dB/cm,which reached a mature silicon-based waveguide loss level.Comprehensive experimental results and various test data show that through continuous optimization of process flow and parameters,the preparation plan of the polymeric optical waveguide can not only produce arbitrary multiple optical waveguides on the PCB,but also has good repeatability and stability.?2?For the optical transceiver components,coupling analysis and structural design are implemented for high-precision coupling requirements during SMT process.First,using the ray optics theory,analyze the optical path and conditions of the laser's vertical exit light coupled into the horizontal optical waveguide through the 45°total reflection mirror.Then,through the numerical simulation,the relationship between the optical coupling efficiency and the angle deviation of the total reflection mirror and the alignment deviation was obtained.The results show that the alignment tolerance of 3 dB loss is about 30?m,the angle tolerance is 2.5³°which reduces the alignment difficulty when the optical transceiver component is mounted.Finally,on the basis of compatibility with SMT technology,a new type of laminated photovoltaic panel structure in which an optical transceiver module is embedded integrally is proposed,and the traditional problem of localized excessive temperature rise due to active devices buried in the panel is effectively solved with finite element analysis to optimize the thermal conductivity of the optical waveguide clad and the core material.?3?For board-level communication systems,system-level modeling and simulation are performed based on computer software.The composition of communication links and the basis for modeling are described in detail.In particular,the optical transmission channel modeling is independently conducted,which is based on the analysis of the optical waveguide's transmission characteristics,the process and performance parameters.Finally,the system's overall simulation results show that when the communication rate is up to10Gbps,the eye diagram's quality of the output signal is fine and the minimum bit error rate is 2×10^-8.