Holistic design of optical phased arrays with wide beam scanning range and high side mode suppression ratio using an improved nutcracker optimization algorithm

Abstract

We propose a hybrid-strategy improved nutcracker optimization algorithm (INOA) with a multi-fitness function to design a non-uniform optical phased array (OPA) with optimized antenna spacing distribution for a wide steering angle and high side mode suppression ratio (SMSR). The global search capability is enhanced by incorporating the good point set initialization and t-distribution perturbation. INOA achieves higher convergence accuracy and faster convergence speed than genetic algorithm (GA) and particle swarm optimization (PSO) algorithm. The results show that INOA requires >60 times and 8 times fewer iterations than GA and PSO, respectively, to reach the same fitness value. In addition, INOA is used to optimize the antenna phase distribution of the non-uniform OPA at different beam steering angles. Using this approach, we design a high-performance 128-element OPA, as an example, achieving a beam scanning range of ±85° and a SMSR of 14.67 dB. Compared to traditional design methods, the proposed approach improves the SMSR by 3.48 dB at 80° and 3.42 dB at 85°, while achieving an improvement of over 6 % in power in the main lobe at large steering angles. Furthermore, we investigated the influence of non-uniform excitation amplitude on the SMSR. It is found that our design has a high tolerance to fabrication error.