Narrow beam and low-sidelobe two-dimensional beam steering on thin-film lithium niobate optical phased array
Abstract
Optical beam steering has become indispensable in free-space optical communications, light detection and ranging (LiDAR), mapping, and projection. Optical phased array (OPA) leads this field, yet conventional versions still suffer from a narrow steering field of view (FOV), insufficient sidelobe suppression, and limited angular resolution. Thin-film lithium niobate (LN), with its strong Pockels electro-optic (EO) effect, offers a powerful integrated-photonics platform to overcome these limitations. Here we present a two-dimensional (2D) EO-steered OPA based on a non-uniformly spaced X-cut thin-film LN ridge-waveguide array. A superlattice ridge design suppresses optical crosstalk to -20 dB, enabling low-sidelobe far-field radiation. Using particle swarm optimization (PSO) method, we transform a uniformly spaced array into an optimized non-uniform design, largely improving angular resolution while maintaining sidelobe suppression. When combined with a single-radiating trapezoidal end-fire emitter incorporating an etched grating, the device produces a main-lobe beam width of 0.99 degree*0.63 degree from an aperture of only 140 um*250 um, achieving a wide 2D steering range of 47 degree*9.36 degree with a 20 dB sidelobe-suppression ratio. These results highlight thin-film LN OPA as a compelling route toward heterogeneous, compact, and high-performance EO beam-steering modules and ultra-miniaturized optical modulators.
Keywords
Cite
@article{arxiv.2506.22124,
title = {Narrow beam and low-sidelobe two-dimensional beam steering on thin-film lithium niobate optical phased array},
author = {Yang Li and Shiyao Deng and Xiao Ma and Ziliang Fang and Shufeng Li and Weikang Xu and Fangheng Fu and Xu Ouyang and Yuming Wei and Tiefeng Yang and Heyuan Guan and Huihui Lu},
journal= {arXiv preprint arXiv:2506.22124},
year = {2025}
}