Engineering light absorption at critical coupling via bound states in the continuum

TL;DR

This paper links bound states in the continuum (BIC) physics with critical coupling to engineer light absorption in 2D materials, demonstrating significant bandwidth manipulation while maintaining high efficiency for optoelectronic applications.

Contribution

It introduces a generalized theory connecting BIC physics with critical coupling for light absorption in 2D material metasurfaces, enabling precise control over absorption properties.

Findings

Absorption bandwidth can be increased by over an order of magnitude.

Maximum absorption efficiency is maintained during bandwidth manipulation.

The approach is applicable to high-efficiency optoelectronic devices.

Abstract

Recent progress in nanophotonics is driven by the desire to engineer light-matter interaction in two-dimensional (2D) materials using high-quality resonances in plasmonic and dielectric structures. Here, we demonstrate a link between the radiation control at critical coupling and the metasurface-based bound states in the continuum (BIC) physics, and develop a generalized theory to engineer light absorption of 2D materials in coupling resonance metasurfaces. In a typical example of hybrid graphene-dielectric metasurfaces, we present the manipulation of absorption bandwidth by more than one order of magnitude by simultaneously adjusting the asymmetry parameter of silicon resonators governed by BIC and the graphene surface conductivity while the absorption efficiency maintains maximum. This work reveals the generalized role of BIC in the radiation control at critical coupling and provides promising strategies in engineering light absorption of 2D materials for high-efficiency optoelectronics device applications, e.g., light emission, detection and modulation.