The Design And Fabrication Of SOI Microring Resonator

The microring resonator based on SOI (Silicon on Insulator) with variety functions is the key component for integrated optics due to its advantage of high integration and is compatible with the COMS processing technology, as well as is suitable for large-scale photoelectric integrated system. It plays an important role of research and application potential in areas of optical filters, optical delay lines, optical buffers, optical switches, optical modulators, wavelength converters, sensors, optical logic gates, lasers and so on. After investigating the research status of microring resonators at home and abroad, this paper designs, fabricates and tests the microring resonators based on SOI by means of combining theoretical analyses, simulation and experiments. This paper mainly focuses on the following aspects:(1)Started from the optical waveguide device based on SOI, the mode and loss feature of light transmission in waveguide were investigated. Simulation analyses and comparison the mode feature variation of optical field by changing the parameters of the waveguide structure, whose impact on the transmission characteristics were discussed. Therefore, based on analyses and optimization the reasonable design structure of the microring resonator was given. Two basic straight-ring resonator transmission models were described, and the coupling parameters and transmission characteristics of each situation were derived in detail by using the coupled mode theory at the same time.(2)The relationship between microring width and the transmission performance as well as the quality factor based on the all-pass microring structure is theoretically analyzed and simulated with the algorithm of the FDTD (Finite Difference Time Domain) method. It shows that the smaller microring width will be greatly increased the radiation loss and the wider the waveguide, the smaller the radiation loss, the higher the quality factor will be. But it will cause a multi-mode waveguide when the waveguide is wide enough. So the microring width should be as larger within the single mode regime, thus can reduce the radiation loss and improve the quality factor of the microring resonator. When the radius of the microring is lOum and the microring width is 600nm, the extinction ratio around the wavelength 1.55um is about 18.2dB, and the quality factor can reach as high as 2.2×105. In this process, the single mode regime and quality factor were realized under the most ideal device performance. The effect of the gap between the ring and the bus waveguide and the pedestal thickness on quality factor was also investigated. The larger the gap, the weaker the coupling, and the higher the quality factor will be. The quality factor will increase sharply with the pedestal thickness decreases, as for the decreases of the radiation loss. The works provide some valuable results for further design and optimization of the SOI microring resonator.(3)Combining with the simulation and analyses results, the layout geometrical parameters of the microring resonators was designed, included the waveguide dimensions, radius, gap and vertical coupling grating and so on. The microring resonator structure draw by L-Edit layout software and then the layout was fabricated based on SOI micromachining. What’s more, the various parameters of production process for the waveguide were discussed and analyzed. The microring resonator test system and the processing were introduced in detail and then the structures were tested and analyzed. Thus, the microring resonator based on SOI was finally accomplished from both the theoretical and the experimental aspects.