Correlation Between SOI Waveguide Topography Error And MZI Device Performance

Important advances in the research and development of silicon on insulator(SOI)waveguides and functional devices have been reported,and the current silicon photonic integration technology has been applied in various fields such as optical data transmission and optical interconnection of chips in fiber optic communications and computers,as well as biomedicine,so SOI waveguides are anticipated to be one of the most promising technology platforms in the field of photonic integrated circuits(PLCs)today.In this thesis,first by studying the dependence of the optical performance of the SOI waveguide Mach-Zehnder interferometer(MZI)type 2×2-optical switch on the waveguide processing quality,the theoretical model for defining the relationship between its optical performance and the geometric dimension(ridge width)error and the waveguide sidewall roughness is established.Further,the intrinsic relationships of the optical output performance of the MZI structure with the geometric size error and the waveguide sidewall roughness are investigated using the theoretical models and the finite difference beam propagation method(FD-BPM)software,respectively,where the co-effect of the actual errors in processing and the measurement accuracy are taken into account.The effects of waveguide sidewall roughness(SWR)and ridge width error(RWE)on the on-chip optical loss(OCL)performance of the device are systematically simulated,and the effect of ridge width error(RWE)on the "through" and "cross" output ports of the device is analyzed.The effect of RWE on the crosstalk(XT)between the "through" and the "cross" output ports of the device is analyzed.The simulation results show that the dependence of OCL on SWR is0.5 d B/nm and the dependence of XT on RWE is 1.2 d B/nm for SOI waveguides with a core layer thickness of 2.0 mm and a ridge width of 2.0 mm.Finally,with the confocal laser scanning microscope system(CLSM),both the geometry and the SWR of real fabricated waveguides are tested and the results of SWR(100～200 nm)beyond the range(10～30 nm)used in the previous simulations.Therefore,the optical output performance of the MZI structure was further simulated based on the actual SWR measurement results,and the performance of the actually fabricated MZI devices in optical loss and isolation(or crosstalk)were tested,and the experimental results were found to be consistent with the simulation results.The theoretical and technical basis established in the article for the relationship between sidewall roughness and waveguide parameters where the effect of errors on waveguide parameters is very useful for the development and exploitation of silicon photonic integrated devices.For example,the results can provide a data basis for the design of MZI-PLC and MZI-PIC devices.