Study On Device Of Ring Resonator Optical Waveguide Based On Lithium Niobate Film

With the development of the new generation of 5G networks and cloud computing,higher requirements are placed on the flexibility and scalability of optical communication networks.Therefore,photonic devices based on different material platforms are proposed to achieve close interconnection of different functional devices,in order to meet the development needs of high-speed optical communication networks.In recent years,due to the excellent comprehensive characteristics and mature processing technology of LNOI,the huge application potential of lithium niobite(LN)in integrated photonics has been explored,and various types of optical communications devices based on LNOI have been developed.The ring resonator,a basic optical device structure,has many advantages for compact structure,high wavelength selectivity,and strong stability.It is widely used in optical communication systems and regarded as an ideal module for achieving miniaturization and high integration.In this paper,combining the excellent performance of LN materials,the new LN optical waveguide device and its performance and application are studied based on the LNOI platform,and the core structure is ring resonator.The research work in this paper provides ideas for the integration of more optical waveguide devices on the LNOI platform,which can promote the development of the LNOI integrated platform.The specific research content and results are as follows:Firstly,the mode loss characteristics of the bend LN waveguide are analyzed,and further study the loss difference between different polarization states,which gives a conclusion that the loss is polarization-dependent.A method of discretizing the non-uniform region into uniform sub-regions is proposed to analyze the coupling characteristics of the pulley waveguide and the ring structure,and the polarization dependence of the coupling and transmission coefficient on the coupling length is calculated.The above research provides theoretical support for the design of polarization selective devices.Secondly,the tunable polarization selective filter device based on the buried waveguide of LNOI is proposed.The device uses the pulley waveguide and resonant cavity structure,combined with the loss of the pulley waveguide and the polarization sensitivity of the coupling coefficient,to achieve the TE and TM polarization separation function.The structural parameters of the LN pulley waveguide and resonant cavity are calculated,and the geometric parameters of the coupling region are optimized.The arc-shaped electrode structure was designed and optimized to realize the tunable function of the filter.The results show that the use of the ring/elliptical ring resonator structure can achieve the TE/TM polarization-sensitive filters,which meet the frequency selection requirements and have the wavelength-polarization dual filter function.At the same time,the filters have excellent performance of the high polarization extinction ratio of 23 d B(TE)and 24 d B(TM),and the high tuning efficiency of 3.6 pm/V(TE)and2.8 pm/V(TM).Thirdly,an optical switching device,assisted by a phase change material GST,based on an LNOI ridge waveguide is proposed.By using the auxiliary structure of the GST layer,which has the huge difference of properties in the amorphous state and the crystalline state loaded on the LN arc waveguide,the resonance state of the light in the ring can be indirectly regulated to realize the off/on function.In this paper,the optimal structural parameters of LN and GST layers are given and the optical properties of GST materials are discussed,and the mode field distribution and mode loss characteristics of the LN waveguide loaded with crystalline and amorphous GST layers are further analyzed,and then the influence of the introduction of GST layer to the operating characteristics of the switch was discussed.The results show that with the aid of GST,an ultra-compact device with a size of 24×23μm~2 can be realized,which has an extinction ratio of 14.2 d B and a free spectral range of 16 nm,and the switch only need low-power when it works because of the self-retaining characteristics of GST materials.