Design Of Microring Filters

In the era of rapid development of society information, the capacity and speed of communication network are constantly improving, high-speed and high-capacity communication network allows integrated optics emerged. Optical microring resonator due to its low cost, versatile, compact structure, etc., has become essential components of integrated optics. Optical filters composed of microring play an important role in fiber communication. In this paper, based on the microring filters as the subject, the basic principle of microring resonator, the analysis method, the design method and transmission characteristics of microring filters were deeply researched.Firstly, the development history and the research status at home and abroad of microring resonator were summarized. The basic principle, basic parameters, topology, applications, and preparation technology of microring were described in detail, which provided a good research foundation for the following.Secondly, the analysis method and the design method of microring filters were researched. Based on the coupled mode theory method and transfer matrix method, the transmission models of microring resonator and series-coupled microring filters were built. In order to design microring filters better, the method based on coupled mode theory and recursive nature of the coupling matrix was introduced. Using this method, microring filters with Butterworth and Bessel response were designed. Next, the method based on the circuit was proposed, series-coupled microring resonator filters were equivalent to a baseband LC ladder network. By solving the element parameters of LC ladder network, the coupling coefficients of microring filters can be obtained. Using this method, microring filters with Chebyshev response were design. To prove the reliability of this method, it was compared with the traditional coupled mode theory method and the ideal Chebyshev response.Finally, based on the return-to-zero(RZ) code and non return-to-zero(NRZ) code, the transmission characteristics of microring filters with different bandwidth B and different ring number N were separately analyzed. Only by selecting the appropriate bandwidth B and ring number N, the better waveform of return-to-zero(RZ) code and non return-to-zero(NRZ) code can be obtained. Based on the complexity of the manufacturing process of higher-order microring filters, dual-mode microring filters composed of three microring were introduced, which could achieve4-oredr filter response by three microring.