Optimization and Modeling for Optical Phased Array

Abstract

The rapid growth of technology these years has brought up the demands on LiDAR.Research on LiDAR has shown a higher detecting range, resolution, and detection speed than microwave radar. As the essential component of LiDAR, the optical phased array plays a fundamental role in the beamforming for the LiDAR.Unlike microwave phased array antennas, optical phased array antennas naturally have grating lobes in the radiation pattern due to the large element spacing in the array.The grating lobes are undesirable since they dissipate energy from the main lobe, reducing the power efficiency of the optical phased array. Eliminating and reducing the grating lobes then become a pressing problem to solve. This thesis presents three types of optical phased arrays: the rectangular, circular, and randomly distributed configurations, to achieve the maximum grating lobes suppression. Using a specific antenna design as the base element, we design and optimize three types of the arrays by implementing the genetic algorithm. We conclude that the rectangular phased arrays have a minor performance on sidelobe suppression compared to the other two types of phased arrays. The randomly distributed phased arrays will have a similar performance on sidelobe suppression compared to the circular phased arrays when over 400 antennas are placed, but it utilizes less device footprint.The circular phased arrays utilize the most device footprint, but it has the narrowest 3 dB beamwidth.