Study Of Silicon Optical Phased Array For Two-dimensional Beam Steering

In recent years,the rapid development of autonomous driving and other commercial fields has spawned the demand for high-precision,miniaturized,and low-cost 3D sensors.However,traditional 3D sensors such as mechanical LIDAR,which is limited by large size and high cost,are difficult to be popularized on a large scale.In this context,silicon optical phased array technology,which can achieve integration,solid-state and high-speed beam scanning,has become one of the hottest research solutions for high-performance low-cost LIDAR.Therefore,the research in this paper is focused on silicon optical phased array.Through the complete process from design,simulation,fabrication to testing,this paper designs and fabricates different silicon optical phased array devices that can realize two-dimensional beam steering.The main research content includes the following aspects:1.Aiming at the problem of the limited scanning range by wavelength adjustment of the one-dimensional optical phased array,a new structure as the symmetrical multi-line optical phased array is proposed.This structure applies two groups of waveguide arrays to connect the two ends of one symmetrical grating antenna array,while these two groups of waveguide arrays are chosen by an optical switch,which can realize symmetrical double-line beam scanning.The main advantage of this structure is increasing the scanning range of the longitudinal beam under the same wavelength range and saving the chip area.The designed 4-wire 64-channel symmetrical multi-line array structure uses two groups of symmetrical antenna arrays with different grating periods,which can cover the quadruple scanning range of the longitudinal beam compared to a single array.The experiment shows that the produced device can achieve a scanning range of 22°×19.7°with wavelength from 1530 to 1570 nm.2.Aiming at the problem of difficult layout and limited scanning range of two-dimensional arrays,a new structure as the two-dimensional non-uniform sparse optical phased array is proposed.This structure combines the characteristics of the one-dimensional non-uniform array and the two-dimensional sparse array,and uses the genetic algorithm to optimize the distribution of antenna elements on the two-dimensional non-uniform grid.Its advantage is that the grating lobes are effectively suppressed and the beam scanning range of the two-dimensional optical phased array is expanded,which only adjusts the phase to realize beam steering.The difficulty of the layout for waveguides is also eliminated.The designed device has 128 antennas,which can realize a beam scanning range of 50°×16°,and the divergence angle of 0.65°×0.66°.In addition,a two-dimensional radiating antenna with small size and high radiation efficiency and a low-power thermal modulator with high modulation efficiency are also designed.The size of the two-dimensional radiating antenna is 4.2×4.36?m~2,and the radiation efficiency is 41.4%.The measured 2?phase power consumption of the low-power thermal modulator is only 11 mW.