Intelligent Design Of Key Components Of Optical Phased Arrav Based On Silicon Nitride

Light detection and ranging has become a research hotspot in the current academic and industrial circles with its broad application prospects in the fields of autonomous driving,environmental monitoring,terrain surveying and mapping.Among them,optical phased array laser radar has outstanding advantages such as small volume,high integration,low power consumption and high stability.It is one of the most potential technical solutions for miniaturized lidar.Compared with silicon,silicon nitride has excellent characteristics such as low loss,low refractive index contrast and large transparent window,which shows huge application potential in the optical phase control array.However,due to the limitations of traditional methods in device design,the performance of silicon nitride optical phase control arrays is still not ideal enough.This article uses inverse design methods to optimize design and characteristics of the key devices of silicon nitride optical phased arrays.The main research results and innovation points obtained are as follows:(1)Non-uniform silicon nitride grating antennas are designed by using direct binary search algorithm.The results show that:In the wavelength range of 1500～1590 nm,the vertical direction scanning angle of the non-uniform grating antennas is 13.2°,and the beam steering efficiency is 0.147°/nm,which is 2.4 times that of the uniform grating antennas;at 1550 nm,the side-mode suppression ratio of the non-uniform grating antennas reaches 4.32 dB,and the side-mode suppression ratio of the uniform grating antennas is only 1.00 dB.In addition,the transmission characteristics of non-uniform grating antennas are also better than the uniform grating antennas.(2)The uniform silicon nitride multimode interference splitters are designed.Within the wavelength range of 1500～1600 nm,the transmission efficiency of the two output waveguides in 1×2 splitter exceeds 46.5%.The coupling ratio of the two output waveguides of the device is 50%,and the excess loss is less than 1 dB;the transmission efficiency of the four waveguides in the 1×4 splitter is about 20%,the excess loss is below 3.7 dB.The four output waveguides of the device at 1550 nm are 25.6%,24.4%,24.4%and 25.6%.