Research On The Principle And Application Of Silicon Based Grating-assisted Contra-directional Coupler

As technology advances, the data produced per day all around the world will be a huge amount. We will need high-performance computing systems to complete the efficient processing of these data, which makes high demands to interconnect technology. Conventional electrical interconnect can further improve the performance of the chip by reducing chip size, increasing integration density and reducing the feature size of the wire, but it will gradually encounter a bottleneck. Replacing electrical interconnection with optical interconnection has been recognized as an effective solution.For the high-speed optical interconnection on-chip and between chips, a variety of multiplexing technology can be utilized to further enhance the communication capacity in addition to only substituting photons for electrons. Wavelength division multiplexing and code division multiplexing have been widely used in optical fiber communication, which still possess reference significance in integrated optical waveguides. In recent years, a variety of multiplexing technology have been realized on chip. In the context of this trend, grating-assisted contra-directional coupling is studied in the thesis. We also proposed new devices to realize a variety of multiplexing technology based on this structure. Details are as follows:(1) The significance of optical interconnection and silicon photonics have been analyzed. In addition, optical waveguide theory, coupled-mode theory and computational methods are also introduced.(2) Coupled-mode theory is used for theoretical analysis of grating-assisted contra-directional coupling structure. And the factors that will affect the spectral characteristics are also studied.(3) Four structure parameters which influence spectral characteristics are analyzed and discussed, including the width of grating, the gap between waveguides, the number of grating periods and the grating structure. Their impact on bandwidth, wavelength, transmission and other characteristics are also summarized.(4) A novel polarization beam splitter based on grating-assisted contra-directional coupler has been proposed, and the design method is also described in detail. Meanwhile, we also proposed a structure that can simultaneously realize mode-division multiplexing and wavelength division multiplexing. Apart from the design of new devices, numerical simulation has also been carried out to verify the feasibility of these devices. Schemes that can improve the grating-assisted contra-directional coupling have also been proposed.(5) Grating-assisted contra-directional couplers have been fabricated in the lab. By the variation of the four structure parameters, their impact on spectrum characteristics has been measured. We have compared and analyzed the measured results and the simulation results. In addition, we have also analyzed and demonstrated the reason that caused the distortion in the measured spectrum.