Research Of Thermo-optical Tuning Characteristics Of Integrated Silicon Optical Waveguides

The thermo-optic effect is one of the main tuning means for tunable integrated photonic devices,and can realize tunable devices such as optical switches and tunable micro-ring resonators.In this thesis,the thermo-optic tuning characteristics of silicon on inulator(SOI)optical waveguides are studied theoretically and experimentally.And 2×2 SOI thermo-optical switches and tunable micro-ring filter are fabricated,tested and analyzed.In the first part of the thesis,the effects of waveguide structure,electrode size,cladding thickness,and air adiabatic trench on the thermo-optic tuning characteristics of SOI optical waveguides were studied by two-dimensional modeling and simulation.The results show that the thermo-optic tuning efficiency of rectangular SOI optical waveguides is more than double that of ridge SOI optical waveguides.For rectangular SOI optical waveguide,the electrode length does not affect the power consumption required for ? phase shift,but the average waveguide temperature and response speed decrease as the electrode length increases.The electrode width does not affect the average waveguide temperature required for ? phase shift,but the power consumption and response time increase as the electrode width becomes wider.Reducing the thickness of the cladding can significantly reduce the power consumption and improve the response speed.However,if too thin,the light absorption by the metal electrode is increased.After adding the air insulation trench,the power consumption of the ? phase shift of the rectangular SOI optical waveguide is reduced by 21.4%,and the response speed is slowed down.The power consumption of the ridge SOI optical waveguide is only reduced by 6.8%,but the response speed is slightly faster.Simulation results on thermal crosstalk characteristics show that the range of thermal crosstalk increases with increasing the electrode size.The safe distance between the ridge SOI optical waveguide and electrode with neglectable thermal crosstalk is larger than that of the rectangular SOI optical waveguide.The air adiabatic trench can effectively reduce the thermal crosstalk range of the rectangular SOI optical waveguide,but has no effect on the ridge SOI optical waveguide.In the second part of the thesis,five kinds of thermo-optical tuning devices are designed and tested.In the thermal crosstalk test,when the distance between the electrode and the tuned waveguide is 30?m,the relative phase shift is reduced to 1%,which is consistent with the simulation results.The crosstalk of the 2×2 symmetrical MZI thermo-optic switch can reach 47.5dB,the insertion loss is about 2dB,the response time is about 33.7?s,and the switching power consumption is about 19.3mW.The two-stage heating electrodes of the cascaded MZI thermo-optic switch are respectively loaded with a power of 6.1mW and 9.3mW,and the splitting ratio is optimal and the extinction ratio can reach 47.3dB.The MZI-coupled micro-ring tunable filter has an extinction ratio of 35.8dB when the loading power of tuning arm is 11.0mW,and wavelength tuning of one FSR(~0.293nm)is achieved when the loading power of the ring is 26.6mW.Finally,the MZI thermo-optic switch with embedded spiral waveguide coved by heating single-electrode is designed.The simulation results show that the power required to achieve ? phase shift is only 12.7mW,which is 40.9% lower than that of straight waveguide with the same length.