Nonreciprocal magneto-optic beam steering of thermal emission
Abstract
Conventional thermal emitters obey Kirchhoff's law of thermal radiation, which ties absorptivity to emissivity and places a fundamental limit on a range of radiative energy technologies and sensing systems. This constraint can be overcome using magneto-optic materials, which exhibit nonreciprocal thermal emission under an applied magnetic field. While the spectral nonreciprocity of magneto-optic devices has been explored theoretically and experimentally, nonreciprocal control over the direction of thermal emission has received far less attention. Here, we propose and numerically demonstrate nonreciprocal beam steering of thermal emission, wherein an applied magnetic field lifts the degeneracy between guided modes at +/- kx, enabling asymmetric and tunable directional thermal emission. We highlight a III-V semiconductor photonic structure operating at 24.5 um, a wavelength with few laser sources. This structure exhibits a nonreciprocity greater than 0.5 between +/- 75 degrees at 50 mT, a peak emissivity asymmetry over 0.6 at 150 mT, and 22 degrees of beam steering between 0 and 1 T. Our approach provides a solid-state means of steering a thermal beam, offering a potential route to magnetically controlled beam scanning of incandescent sources.
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BibTeX
@misc{christiansen2026nonreciprocal,
title = {{Nonreciprocal magneto-optic beam steering of thermal emission}},
author = {Mason Christiansen and Daniel Cui and Aaswath P. Raman},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.33935},
eprint = {2610.33935},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.33935},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Nonreciprocal magneto-optic beam steering of thermal emission
AU - Mason Christiansen
AU - Daniel Cui
AU - Aaswath P. Raman
PY - 2026
DA - 2026/10/24
PB - arXiv
DO - 10.48550/arxiv.2610.33935
UR - https://arxiv.org/abs/2610.33935
AB - Conventional thermal emitters obey Kirchhoff's law of thermal radiation, which ties absorptivity to emissivity and places a fundamental limit on a range of radiative energy technologies and sensing systems. This constraint can be overcome using magneto-optic materials, which exhibit nonreciprocal thermal emission under an applied magnetic field. While the spectral nonreciprocity of magneto-optic devices has been explored theoretically and experimentally, nonreciprocal control over the direction of thermal emission has received far less attention. Here, we propose and numerically demonstrate nonreciprocal beam steering of thermal emission, wherein an applied magnetic field lifts the degeneracy between guided modes at +/- kx, enabling asymmetric and tunable directional thermal emission. We highlight a III-V semiconductor photonic structure operating at 24.5 um, a wavelength with few laser sources. This structure exhibits a nonreciprocity greater than 0.5 between +/- 75 degrees at 50 mT, a peak emissivity asymmetry over 0.6 at 150 mT, and 22 degrees of beam steering between 0 and 1 T. Our approach provides a solid-state means of steering a thermal beam, offering a potential route to magnetically controlled beam scanning of incandescent sources.
ER -