High-Efficiency Silicon-Lithium Niobate Grating Coupler enabled by Fully-Etched Subwavelength Structures
Year: 2026
Type: preprint
Abstract: A new approach of silicon-lithium niobate (Si-LN) grating couplers (GCs) with a fully-etched structure is proposed. The coupling strength is engineered through subwavelength structures, allowing improved directionality. The adjoint-based inverse design method is simultaneously adopted to achieve efficient coupling between photonic circuits and fibers. Considering the birefringence of LN, the proposed Si-LN GCs are optimized and fabricated for TE mode along the crystallographic Z and Y directions. The experimentally measured coupling efficiencies are -3.3 dB and -3.9 dB along the crystallographic Z and Y directions, respectively. The measured 3-dB bandwidths are broader than 54 nm and the back reflections can be suppressed down to -15 dB over 50 nm for both directions. The proposed Si-LN GCs are realized by only single-step Si etching, offering a practical solution for fast device prototyping in Si-LN photonic integrated circuits.
Source: arXiv (Cornell University)
Authors: Wang, Jing, Liu, Yang, Su, Shitong, Zou, Weiwen
Institution: Shanghai Jiao Tong University
Language: English
Topic: Photonic and Optical Devices
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Award: G7222182951
OpenAlex ID: W7223027386