Breakdown of Bulk-Radiation Correspondence in Radiative Photonic Lattices

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Main Authors: Yuan, Xinyi, Malgrey, Loïc, Sigurðsson, Helgi, Nguyen, Hai Son, Salerno, Grazia
Format: Preprint
Published: 2025
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author Yuan, Xinyi
Malgrey, Loïc
Sigurðsson, Helgi
Nguyen, Hai Son
Salerno, Grazia
author_facet Yuan, Xinyi
Malgrey, Loïc
Sigurðsson, Helgi
Nguyen, Hai Son
Salerno, Grazia
contents The topological characteristics of energy bands in crystalline systems are encapsulated in the Berry curvature of the bulk Bloch states. In photonic crystal slabs, far-field emission from guided resonances naturally provides a non-invasive way to probe the embedded wavefunctions, raising the question of how the information carried by escaping photons relates to the band topology. We develop a non-Hermitian model to describe the guided and leaky modes of photonic crystal slabs with long-range couplings and non-local responses. Within this framework, radiation Berry curvature is defined from the far-field polarization and compared to the conventional bulk Berry curvature of the crystal Bloch modes. We investigate this bulk-radiation correspondence in the vicinity of the $Γ$-point of the square lattice and the $K$-point of the honeycomb lattice. The results show that the comparability between the bulk topology and the radiation topology is not universal; the validity is contingent upon the specific bulk Bloch states. Notably, the correspondence completely breaks down surrounding the far-field singularities, while it can hold in smooth regions under special symmetry conditions, e.g., rotational symmetry. Besides, net Berry curvature concentration is captured at the valleys of the non-local honeycomb lattice, facilitating further exploration on generalized topological phases in photonic lattices beyond the regimes with localized couplings and Hermiticity.
format Preprint
id arxiv_https___arxiv_org_abs_2504_05188
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Breakdown of Bulk-Radiation Correspondence in Radiative Photonic Lattices
Yuan, Xinyi
Malgrey, Loïc
Sigurðsson, Helgi
Nguyen, Hai Son
Salerno, Grazia
Optics
Mesoscale and Nanoscale Physics
The topological characteristics of energy bands in crystalline systems are encapsulated in the Berry curvature of the bulk Bloch states. In photonic crystal slabs, far-field emission from guided resonances naturally provides a non-invasive way to probe the embedded wavefunctions, raising the question of how the information carried by escaping photons relates to the band topology. We develop a non-Hermitian model to describe the guided and leaky modes of photonic crystal slabs with long-range couplings and non-local responses. Within this framework, radiation Berry curvature is defined from the far-field polarization and compared to the conventional bulk Berry curvature of the crystal Bloch modes. We investigate this bulk-radiation correspondence in the vicinity of the $Γ$-point of the square lattice and the $K$-point of the honeycomb lattice. The results show that the comparability between the bulk topology and the radiation topology is not universal; the validity is contingent upon the specific bulk Bloch states. Notably, the correspondence completely breaks down surrounding the far-field singularities, while it can hold in smooth regions under special symmetry conditions, e.g., rotational symmetry. Besides, net Berry curvature concentration is captured at the valleys of the non-local honeycomb lattice, facilitating further exploration on generalized topological phases in photonic lattices beyond the regimes with localized couplings and Hermiticity.
title Breakdown of Bulk-Radiation Correspondence in Radiative Photonic Lattices
topic Optics
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2504.05188