Abstract

Bound states in the continuum (BICs) have emerged at the forefront of optics and nanophotonics due to their exceptionally high quality-factors and unique topological characteristics. Advances in design capabilities, nanofabrication and characterization have enabled precise control of BIC resonances at subwavelength scale, unlocking exciting opportunities for applications in diverse areas such as lasing, optical sensing and nonlinear optics.

The integration of phase-change materials and liquid crystals has facilitated dynamic control over light emission and absorption. In this Review, we provide a comprehensive overview of the latest progress in BIC research, covering both foundational concepts and recent advances. We begin with the underlying physics and highlight emerging design strategies, including machine learning and inverse design approaches. We discuss major breakthroughs in super-BICs, chiral BICs, intriguing concepts of flatband BICs and Moiré BICs, along with exotic phenomena, such as strong light-matter interaction, ultrafast dynamics and exceptional points.

We further review the recent advancements and key challenges in BIC-enabled applications. Finally, we offer our perspectives on the promising future of BIC in fundamental research emphasizing emerging directions such as multilayer metasurfaces, interfacing BICs with quantum emitters, new capabilities enabled by advanced fabrication and design, and pathways towards scalable integration into photonic BIC metadevices.