Magnetic Lifting of BIC Symmetry Protection Enables Nonreciprocal Beam Steering and Angular Information Encoding
Abstract
Symmetry-protected bound states in the continuum (SP-BICs) offer exceptional optical confinement but remain nonradiative. Here, we demonstrate that magnetically lifting their protecting symmetry enables nonreciprocal beam steering with intrinsic angular information encoding. In a magneto-optical photonic crystal slab, an in-plane magnetic field converts an SP-BIC into a radiative quasi-BIC and, together with vertical dielectric asymmetry, continuously displaces the associated band extremum away from the Gamma point. The steered beam exhibits two independent locking relations: its wavelength is locked to the elevation angle, while its polarization orientation is locked to the azimuthal angle. These relations embed complementary spectral and polarization information into the scanning beam, providing additional sensing channels for multidimensional LiDAR. Moreover, the nonreciprocal dispersion gives different resonance frequencies at opposite wave vectors, supporting resonant emission at +k while back-reflected light at the same frequency is off resonance at -k, opening a route to intrinsic self-isolation and reduced optical feedback. These findings establish a unified framework connecting magnetic beam steering, angular information encoding, and nonreciprocal feedback suppression, with prospects for compact reconfigurable light sources and integrated optical engines.
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BibTeX
@misc{zhang2026magnetic,
title = {{Magnetic Lifting of BIC Symmetry Protection Enables Nonreciprocal Beam Steering and Angular Information Encoding}},
author = {Chengrui Zhang and Zijing Xianyu and Chufan Zhou and Qi Jiang and Shengxuan Si and Wanli Xue and Ji Wu and Haoming Zhong and Jiaqi Zhang and Hanqi He and Edoardo Charbon and Zhiyu Wang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.27525},
eprint = {2609.27525},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.27525},
}
RIS
TY - UNPB
TI - Magnetic Lifting of BIC Symmetry Protection Enables Nonreciprocal Beam Steering and Angular Information Encoding
AU - Chengrui Zhang
AU - Zijing Xianyu
AU - Chufan Zhou
AU - Qi Jiang
AU - Shengxuan Si
AU - Wanli Xue
AU - Ji Wu
AU - Haoming Zhong
AU - Jiaqi Zhang
AU - Hanqi He
AU - Edoardo Charbon
AU - Zhiyu Wang
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.27525
UR - https://arxiv.org/abs/2609.27525
AB - Symmetry-protected bound states in the continuum (SP-BICs) offer exceptional optical confinement but remain nonradiative. Here, we demonstrate that magnetically lifting their protecting symmetry enables nonreciprocal beam steering with intrinsic angular information encoding. In a magneto-optical photonic crystal slab, an in-plane magnetic field converts an SP-BIC into a radiative quasi-BIC and, together with vertical dielectric asymmetry, continuously displaces the associated band extremum away from the Gamma point. The steered beam exhibits two independent locking relations: its wavelength is locked to the elevation angle, while its polarization orientation is locked to the azimuthal angle. These relations embed complementary spectral and polarization information into the scanning beam, providing additional sensing channels for multidimensional LiDAR. Moreover, the nonreciprocal dispersion gives different resonance frequencies at opposite wave vectors, supporting resonant emission at +k while back-reflected light at the same frequency is off resonance at -k, opening a route to intrinsic self-isolation and reduced optical feedback. These findings establish a unified framework connecting magnetic beam steering, angular information encoding, and nonreciprocal feedback suppression, with prospects for compact reconfigurable light sources and integrated optical engines.
ER -