Design And Research On Silicon Photonic Input And Output Devices

The explosion of information is driving the demand on communication capacity in the infrastructure like data centers and supercomputers.As the electrical interconnect technologies are approaching their performance limits,optical interconnects have become a disruptive choice for continuing Moore's Law.Under such background,silicon photonic technologies have attracted the great interests as they would leverage the microelectronic industry by fully utilizing the mature microelectronic processing technology and optical interconnect with the virtues of high bandwidth,low power consumption and electromagnetic immunity.The silicon photonics have been viewed as a key platform for the next generation integrated optical interconnect.The industrialization of silicon photonics have encountered the various challenges including the lasering and coupling.The material properties of silicon determine its ultralow efficiency of lasering,therefore it is necessary to introduce the external III-V light source to the silicon optical chip.By doing so,the performance of coupling directly determines the power budget for the system-on-chip,and the cost of the coupling also affects the economic feasibility of the proposed solution.Besides,the design methodology of silicon photonic devices would have great impact on the progress of large-scale integration on silicon optical chips.Therefore,another research topic is inverse design based silicon photonic devices.The research work in this paper will mainly include two parts,one is to study on input and output devices for silicon photonics chip,and the other is to optimize the inverse design method of the device.The corresponding research contents and innovative outcomes are as follows:1)Theoretic research on the grating coupler and fiber connector,and design a 24-channel coupling scheme for the multi-channel input and output requirements,and finally realize the multi-channel coupling chip with substantial testing results.2)Propose two polarization independent coupling schemes,aiming to eliminate the polarization controller for fiber-chip coupling and realize a low-cost,high-density fiber-waveguide coupler.Both designs are verified by simulation.A fully-vertical polarization-independent grating coupler is proposed to achieve a coupling loss and flatness of-4.56 ± 0.15 dB,and a coupler with a incidence angle is also proposed to achieve a coupling loss and flatness of-5.7 ± 0.53 dB.3)Propose an elliptical multimode interferometer for the edge and vertical dual-incident coupler.The elliptical multimode interferometer with primary and secondary dual-channel is designed to achieve a transmission loss of-0.139 dB for the main waveguide and a transmission loss of-1.126 dB for the primary waveguide at 1550 nm.Another symmetric coupler is realized with the transmission loss of both channels is below-0.22 dB.Besides,the device also allows arbitrary proportional coupling with low insertion loss for both channels.The 2D grating coupler is combined with the multimode interferometer to realize a polarization insensitive coupler and ±0.05 dB flatness with arbitrary incident polarization angle is achieved.4)Optimize the inverse design method by Gaussian fuzzy algorithm,extract the feature of the inverse design of ultra-small waveguide bend,and use the form of grating to realize the 180° waveguide bend with ultra-small bending radius.0.6 ?m U-turn is designed,and the transmission spectral bandwidth is much higher than the corresponding inverse design result.The 80% transmission efficiency is achieved in the entire C+L band.