Applications of Bound States in the Continuum in Photonics

TL;DR

This review explores the properties, phenomena, and diverse applications of bound states in the continuum (BICs) in photonics, highlighting their potential in lasing, sensing, and topological photonics.

Contribution

It provides a comprehensive overview of BICs, detailing their unique properties, derived phenomena, and emerging research frontiers in photonics.

Findings

BICs enable enhanced light confinement and sharp resonances.

BICs facilitate topological and polarization control in photonic devices.

Applications include lasing, nonlinear conversion, waveguiding, and sensing.

Abstract

Bound states in the continuum (BICs) have attracted attention in photonics owing to their interesting properties. For example, BICs can effectively confine light in a counter-intuitive way and the far-field radiation of photonic structures that exhibit BICs manifests fascinating topological characteristics. Early research into photonic BICs was primarily focused on designing artificial structures to produce BICs. However, since the mid-2010s, exploring the potential applications of BICs has been a growing trend in research. In this Review, we detail the unique properties of BICs, including the ability to achieve enhanced light confinement, sharp Fano resonances, and topological characteristics. We also explore phenomena derived from BICs including the generation of circularly polarized states and unidirectional guided resonances and the impact of BICs on various applications such as lasing, nonlinear frequency conversion, waveguiding, sensing and wavefront control. We also discuss the insights provided by BICs in several emerging research frontiers, such as parity-time symmetric systems, higher-order topology, exciton-photon coupling, and moir\'e superlattices.