Research On SOI Microring Resonator Filters

Recently, optical devices based on silicon-on-insulator(SOI) has been regarded as an ideal platform for the optical large-scale integrated circuits as its compacted structure, superior performance and its fabrication compatibility with CMOS process. Micro-ring resonator based on SOI as one of the optical devices are considered as critical building blocks for photonic integrated circuit due to its high Q factor and compacted structure. Now, the MRR(micro-ring resonator) has been widely used in optical filters, switches, modulator, detector and many other integrated devices. In order to improve the performance of MRR,this thesis designed a new kind of concentric microring resonator with diffrent waveguide width.The main research work and innovation are as below.1. Mechanism and main performance parameter of microring resonator was investigated. The coupling ratio between straight waveguide and bending waveguide was derived, also the coupling ratio between two bending waveguides by the method of mode-coupling theory. The expression of main performance parameter was deduced. Transfer function of single-ring structure, cascade-ring structure and especially concentric-ring structure was worked out through tranfer matrix method and mode-coupling method.2. A new kind of concentric microring resonator with diffrent waveguide width was proposed. The structure included one input waveguide and two concentric ring waveguide with diffrent waveguide width. The concentric microring resonator structure was analyzed theoretically and the expression of new structure’s transfer function and the critical mutual coupling coefficient was derived. Then the simulation result of new structure was analyzed and found that the new structure can improve the resonance depth, also eliminate the side-mode suppression at the same time. Compared the simulation result of new strucure with single ring structure, the resonace depeth was improved by35dB, and FWHM(Full Width at Half Maximum) is reduced to0.5nm. In addition, a new concentric micro-ring structure with30m FSR (Free Spectrum Range) and30dB resonance depth was proposed.3. A new filter structure with multi-concentric microring waveguides was proposed. The new structure was composed of one input waveguide and four concentric microring with same waveguide width. When analyzing the simulation result of new structure’s transfer spectrum, the spectrum was box-like at the1565nm. Compared with former series micro-ring structure, the new multi concentric microring resonator filter has smaller size and much compacted.4. The new concentric microring resonator structure was designed and its performance was tested with the experimental test platform. The experimental result which was in agreement with the result of theory and simulation proved the correctness of the theoretical design.