Chirality-driven all-optical image differentiation
Author(s)
Koufidis, Stefanos Fr
Hayran, Zeki
Monticone, Francesco
Pendry, John
McCall, Martin W
Type
Journal Article
Abstract
Optical analog computing enables powerful functionalities, including spatial differentiation, image processing, and ultrafast linear operations. Yet, most existing approaches rely on resonant or periodic structures, whose performance is strongly wavelength-dependent, imposing bandwidth limitations and demanding stringent fabrication tolerances. Here, to address some of these challenges, we introduce a highly tunable platform for optical processing, composed of two cascaded uniform slabs exhibiting both circular and linear birefringence, whose response exhibits features relevant to optical processing without relying on resonances. Specifically, using a coupled-wave theory framework we show that sharp reflection minima, referred to as spectral holes, emerge from destructive interference between counter-propagating circularly polarized waves in uniform birefringent slabs, and can be engineered solely through parameter tuning without requiring any spatial periodicity. When operated in the negative-refraction regime enabled by giant chirality, the interference response acquires a highly parabolic form around the reflection minimum, giving rise to a polarization-selective Laplacian-like operator that performs accurate spatial differentiation over a broad spatial-frequency range. This functionality is demonstrated through an edge-detection proof of concept. The required material parameters align closely with recent experimental demonstrations of giant, tunable chirality via meta-optics, presenting a promising pathway towards compact and reconfigurable platforms for all-optical pattern recognition and image restoration.
Date Issued
2025-12-01
Date Acceptance
2025-11-20
Citation
Nanophotonics, 2025, 14 (27), pp.5449-5464
ISSN
2192-8606
Publisher
De Gruyter
Start Page
5449
End Page
5464
Journal / Book Title
Nanophotonics
Volume
14
Issue
27
Copyright Statement
Open Access © 2025 the author(s), published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License.
License URL
Identifier
10.1515/nanoph-2025-0479
Subjects
analog computing
chirality
image differentiation
Laplacian
metamaterials
spectral engineering
Publication Status
Published
Date Publish Online
2025-12-09