Work

Near-perfect light absorption via degenerate quasi-bound states in the continuum in double-sided gratings with broken in-plane C 2 symmetry

Year: 2026

Type: article

Abstract: We demonstrate that near-perfect light absorption can be achieved by exploiting degenerate quasi-bound states in the continuum (quasi-BICs) supported by one-dimensional double-sided gratings (DSGs) with broken in-plane C 2 symmetry. Using a two-step iterative optimization procedure, the grating parameters are identified such that two quasi-BICs become spectrally degenerate while their radiative and nonradiative quality ( Q ) factors are nearly balanced. Our results show that once exact frequency degeneracy is achieved, approximate satisfaction of the critical coupling condition is sufficient to yield near-unity absorption. We further demonstrate the universality of the proposed DSG-based absorber by designing structures operating in the telecommunication, terahertz, and microwave regimes using different materials, including germanium, doped silicon, and alumina. In particular, low-loss materials are shown to significantly enhance spectral selectivity through higher absorbance Q factors. These findings establish asymmetric DSGs as a flexible and effective platform for designing high-performance all-dielectric light absorbers for diverse optoelectronic applications.

Source: Optics Express

Authors: Sun-Goo Lee, Kap-Joong Kim, Wook-Jae Lee

Institution: Electronics and Telecommunications Research Institute

Language: English

Topic: Metamaterials and Metasurfaces Applications

Subfield: Electronic, Optical and Magnetic Materials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,270

Funders: Kongju National University, National Research Foundation of Korea

Award: G6911555431