Broadband chiroptical sensing with two-mode subwavelength grating waveguides
Abstract
Engineering local optical chirality in planar photonic structures offers a route to selective and enhanced light-matter interactions with chiral media. Here, we introduce periodic dielectric waveguides that support chiral evanescent fields through the interaction of two nearly degenerate waveguide modes. We develop a perturbation theory for such a waveguide covered by a chiral layer, relating chirality-induced modal coupling and propagation-constant corrections to measurable intermodal power conversion and differential transmission. Whereas modal detuning confines the chiral response of a symmetric waveguide to a narrow spectral range, mode hybridization in an asymmetric waveguide creates individual eigenmodes that carry nonzero local chirality over a broad spectral range. We show that modal dichroism in realistic lossy waveguides can produce a significant background differential transmission signal. Such a background, however, can be suppressed by comparing transmission through two asymmetric waveguides with opposite structural asymmetries, allowing the chiral response to be reliably extracted. Together, these findings provide a basis for developing integrated photonic components with locally chiral fields, including waveguides, metasurfaces, and resonators.
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BibTeX
@misc{seredin2026broadband,
title = {{Broadband chiroptical sensing with two-mode subwavelength grating waveguides}},
author = {Albert A. Seredin and Roman S. Savelev},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.23630},
eprint = {2610.23630},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.23630},
}
RIS
TY - UNPB
TI - Broadband chiroptical sensing with two-mode subwavelength grating waveguides
AU - Albert A. Seredin
AU - Roman S. Savelev
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2610.23630
UR - https://arxiv.org/abs/2610.23630
AB - Engineering local optical chirality in planar photonic structures offers a route to selective and enhanced light-matter interactions with chiral media. Here, we introduce periodic dielectric waveguides that support chiral evanescent fields through the interaction of two nearly degenerate waveguide modes. We develop a perturbation theory for such a waveguide covered by a chiral layer, relating chirality-induced modal coupling and propagation-constant corrections to measurable intermodal power conversion and differential transmission. Whereas modal detuning confines the chiral response of a symmetric waveguide to a narrow spectral range, mode hybridization in an asymmetric waveguide creates individual eigenmodes that carry nonzero local chirality over a broad spectral range. We show that modal dichroism in realistic lossy waveguides can produce a significant background differential transmission signal. Such a background, however, can be suppressed by comparing transmission through two asymmetric waveguides with opposite structural asymmetries, allowing the chiral response to be reliably extracted. Together, these findings provide a basis for developing integrated photonic components with locally chiral fields, including waveguides, metasurfaces, and resonators.
ER -