Backward-Emitting Antenna Based on Ridge Subwavelength Grating Array Enabled High Wavelength Sensitivity

Optical antennas are the key components for optical phased array (OPA). In this work, we demonstrate backward-emitting antenna based on ridge structure with a beam divergence of 0.13° and a wavelength sensitivity up to 0.237°/nm.

I. Introduction

Optical phased array (OPA), with excellent functional beam manipulation characteristics, provides potential solutions for important fields such as Light detection and ranging (LiDAR) and free-space data communications [1]. Integrated optical antenna is an essential element for OPA to interact with free space, providing nanoscale compact, lightweight scanning systems without relying on complex mechanical transceiver components to cover the entire application scenario [2]. Silicon on insulator (SOI) is an important platform [3] with significant advantages ranging from optical communications to biomedicine, and LiDAR. However, the typical waveguide grating antennas show a wavelength scanning sensitivity of 0.14 to 0.17°/nm [4], resulting in a narrow longitudinal scanning range. Therefore, silicon optical phased arrays need a wide beam scanning range while ensuring weak grating strength.