Design And Research Of SOI Based Optical Waveguide Related Devices

With the improvement of the speed of information communication and optical communication in modern society,waveguide related devices used in optical communication have been paid attention to because their sizes are small and their costs are low.Because waveguide devices are connected by waveguides,they are more conducive to integration than traditional optoelectronic devices.The integrated Mach Zehnder Modulator(MZM)is a waveguide device system,mainly including optical waveguide,grating coupler and Mach Zehnder Interferometer(MZI).It has the advantages of fast modulation speed and simpler process compared with other modulators.In order to realize the optical modulator with small size and high modulation efficiency,this thesis designs the components of MZM include waveguide,grating coupler and MZI based on silicon on insulators,optimizes the parameters through simulation design,and makes and experiment the waveguide and grating coupler chips.The work completed in this thesis includes:Firstly,the silicon waveguide coated with silicon dioxide was selected and Lumerical simulation software was used to simulate the waveguide,grating coupler and MZI.The single-mode condition of the waveguide is solved,and it is confirmed that the strip waveguide and rib waveguide can realize single-mode transmission at 220 nm high and 500 nm wide.The size parameters of the grating coupler were optimized,and the coupling efficiency of the optimized grating was 62%,the alignment tolerance of-3dB was 7.3 ?m,and the spectral characteristics were obtained.The modulation efficiency of MZI is calculated.At 5 V voltage,the phase difference ? between MZI arm and MZI arm can be caused by 4.47 mm length,and how process doping and voltage affect the modulation efficiency of MZI is analyzed.Then,according to the simulation design layout,two flow sheets are carried out.The first one is for the fabrication of waveguide,grating coupler and multi-mode interferometer,which do not need doping process and electrode,to reduce the complexity of the process.After the fabrication process is evaluated,the second flow sheet is made for the whole MZM.The test results show that the transmission loss of strip waveguide is 2.4 d B/cm,and that of ridge waveguide is 2.0 d B/cm.The best coupling efficiency of grating couplers is 4.4 d B,which indicates that the waveguide and grating couplers can be used in MZM.In addition,in order to quantitatively analyze the proportion of different transmission loss in optical waveguide,the basis for reducing transmission loss is provided.On the basis of summarizing the test data,this thesis presents a method to calculate the specific proportion of the loss caused by different mechanisms in the optical waveguide.Finally,59.2% of the transmission loss of the strip straight waveguide in this experiment is surface scattering loss,40.8% is internal scattering loss,mode mismatch loss can be ignored.