High-Efficiency Silicon-Lithium Niobate Grating Coupler enabled by Fully-Etched Subwavelength Structures
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.
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BibTeX
@misc{wang2026highefficiency,
title = {{High-Efficiency Silicon-Lithium Niobate Grating Coupler enabled by Fully-Etched Subwavelength Structures}},
author = {Jing Wang and Yang Liu and Shitong Su and Weiwen Zou},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.25839},
eprint = {2610.25839},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.25839},
}
RIS
TY - UNPB
TI - High-Efficiency Silicon-Lithium Niobate Grating Coupler enabled by Fully-Etched Subwavelength Structures
AU - Jing Wang
AU - Yang Liu
AU - Shitong Su
AU - Weiwen Zou
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.25839
UR - https://arxiv.org/abs/2610.25839
AB - 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.
ER -