Subwavelength structure enabled ultra-long waveguide grating antenna
Jiaxin Chen, Jinzhao Wang, Jiewen Li, Yong Yao, Yunxu Sun, Jiajun Tian, Yi Zou, Xiangjie Zhao, Xiaochuan Xu
Abstract
Because of the high index contrast, current silicon photonics based optical phased arrays cannot achieve small beam divergence and large field-of-view simultaneously without increasing fabrication complexity. To resolve the dilemma, we propose an ultra-long waveguide grating antenna formed by placing subwavelength segments within the evanescent field of a conventional strip waveguide. Bound state in the continuum effect is leveraged to suppress the sidewall emission. As a proof of concept, we theoretically demonstrated a millimeter-long through-etched waveguide grating antenna with a divergence angle of 0.081° and a feature size compatible with current silicon photonics foundries.