Inverse-design Of Waveguide Couplers On SOI Based Particle Swarm Optimization

Silicon-based photonic integrated device has significant advantages such as high speed,low power consumption and high integration,which makes it become one of the ideal technologies to break through the bottleneck of current information transmission and processing.The silicon-based waveguide coupler is an important passive device to connect the silicon-based devices.However,the footprint of the waveguide coupler obtained by traditional methods cannot meet the requirements of silicon-based photonic integration.Inverse-design is one of the most potential ways to realize ultra-compact silicon-based integrated nanophotonic devices,which is expected to achieve better device performance in smaller footprint.In this dissertation,we use particle swarm optimization algorithm to design the geometry of ultra-compact silicon-based directional coupler and multimode interference coupler,use electromagnetic simulation to research the performance of the device.The main research results are as follows:(1)Two 2 × 2 cross directional optical couplers working in TE mode and TM mode on silicon-on-insulator(SOI)are designed by a particle swarm optimized inverse-design method.The footprint of the devices both are 2 ?m × ?m.The simulation results show that the coupling efficiency of TE and TM mode directional couplers is 69.1%and 89.7%at 1550 nm,respectively,and the wavelength range of coupling efficiency above 60%is 90 nm and 125 nm,respectively.In addition,we verify that the device has high tolerance to waveguide width,spacing and pixel side length.(2)A 3 × 3 directional coupler with the footprint of 2 ?m × 2?m is designed by using particle swarm optimization algorithm,which can couple the light from an input port to a specified output port.The coupling efficiency of the three transmission paths of the device reaches 49.3%,57.6%and 49.0%respectively at 1550 nm.In addition,the other two 3×3 directional couplers with different transmission paths are realized by adjusting the device structure.(3)The 1 × 2 and 1×3 multimode interference couplers which could realize uniform beam splitting are designed by particle swarm optimization algorithm,and the footprint of each device is 2 ?m ×2 ?m.The simulation results show that the operating bandwidth of 1 × 2 and 1 × 3 MMI couplers are 55 nm and 40 nm respectively,and the transmission efficiency of each output waveguide at 1550 nm is 46.4%and 21.4%respectively.