Reconfigurable Filter Array On Silicon Nitride Waveguide And Its Application

With the rapid development of modern communication networks,computer networks and its related industries,the next-generation network will focus on the optical-communication network in order to meet the increasing communication capacity.Due to the integration and microminiaturization of the information processing system in the optical communication network,integrated photonic devices have also been developed rapidly.The optical micro-ring resonator is one of the basic integrated photonic devices because of its low cost,compact size versatility and other advantages.Compared to polymer,silicon nitride has the advantages of large refractive index difference,compact size for high density integration and stable performance.Also,compared to silicon-on-insulator,the silicon nitride waveguide has the advantage of easy fabrication and low cost Silicon nitride micro-ring resonator has a wide range of applications,such as microwave photonic filters,optical modulators,delay lines and so on.In this thesis,the design,fabrication and testing of reconfigurable micro-ring resonator filter array based on silicon nitride waveguide was studied.introduced the theory of reconfigurable filter based on the micro-ring resonator coupled with the Mach-Zehnder interferometer by using the transfer matrix method;Then the single-mode silicon nitride waveguide,bending radius and coupling region of the ring resonator were designed and optimized;And the thermo-optic tuning characteristics of the silicon nitride waveguide were explored accordingly;Based on the above theories,a kind of silicon nitride reconfigurable filter array was designed.Then the optical waveguide and electrode mask were designed and fabricated,and the single micro-ring resonator filter unit and the six-ring cascaded reconfigurable filter array were successfully fabricated by optimizing the micro-fabrication process,such as the photolithography and the reactive ion etching.The static response of the fabricated single micro-ring resonator filter was measured and the results show that its free spectral range is 0.1389nm,the full width at half-maximum is 0.039nm,the extinction ratio is 25dB and the quality factor Q is 40000.Then the tuning characteristics of the reconfigurable filter array composed of six cascade micro-ring resonators were measured and the results show that the resonant wavelength and extinction ratio of each micro-ring can be tuned by applying voltage to the electrodes on the MZI and the ring.Finally,in order to overcome the polarization dependence of the silicon nitride waveguides in the device,a polarization splitter-rotator based on silicon nitride optical waveguide was designed and optimized.