Research On Polarization-Independent Microring Resonators And Its Application

Microring resonators which have the advantages of compact structure and easy phase matching,are widely used in the design and preparation of wavelength division multiplexers/demultiplexers.However,most of the microring resonators are polarization-dependent,which is difficult to meet the requirements in practical applications.Therefore,the research on polarization-independent microring resonators has import application value.Based on the mode coupling principie and resonance equation two different polarization-independent microring resonators are designed and applied to wavelength division multiplexing/demultiplexing in this paper.The specific research contents and innovations are as follows.(1)A polarization-independent microring resonator based on sub-wavelength grating and sandwiched structure is proposed.The sub-wavelength grating is designed and optimized rationally to realize the polarization independence of the coupling region.The refractive index of Si N_x in the sandwiched structure is adjusted to realize the polarization independence of the resonance wavelengths.The results show that the radiu of the ring is only 10?m;and the insertion loss of different polarization states is less than 0.8dB and the 3-dB bandwidth is lower than 0.8nm.(2)A polarization-independent dual-microring resonator based on sub-wavelength grating is proposed.The sub-wavelength grating is designed and optimized rationally to realize the polarization independence of the coupling region.A racetrack microring waveguide is embedded in the microring waveguide to realize the polarization independence of the resonance wavelengths.The results show that the radiu of the ring is only 10?m;and the insertion loss of different polarization states is less than 1dB and the 3-dB bandwidth is less than 0.8nm.(3)The two proposed polarization-independent microring resonators are applied to the design of wavelength division multiplexer/demultiplexer.Two different design schemes for polarization-independent wavelength division multiplexer/demultiplexer are proposed respectively.In addition,by connecting two microring resonators in series,the performance of the wavelength division multiplexer/demultiplexer unit is optimized.In summary,two kinds of microring resonators based on different structures are designed in this paper,which not only realize the polarization-independent function,but also have the advantages of small size and easy integration.In addition,they are applied to the design of two different polarization-independent four-channel wavelength division multiplexing/demultiplexing,which have potential application value in future optical networks.