Bound states in the continuum (BICs) are localized states whose energies reside within the continuum of radiating modes. Optical BICs allow for the realization of photonic resonances with ultra-high Q-factors and far-field vortex beams, making them prime candidates for inducing exotic light-matter interactions. In this presentation, we explore the engineering of optical BICs within moiré photonic crystal (PhC) slabs. First, we demonstrate moiré flat-band quasi-BICs in a twisted bilayer PhC slab. Next, by controlling multiple topological charges, we theoretically design and experimentally realize a perfect moiré BIC in 1D PhC slabs. Finally, we extend the concept of BICs to quasi-bound flat bands in the continuum (BFICs), where all Bloch modes in a flat band exhibit the quasi-BIC behavior across all k-points above the light line. We propose two methods for realizing quasi-BFICs: the moiré design, and the counterintuitive disorder effects, which can randomly give rise to quasi-BFICs.

张蔚暄，北京理工大学物理学院教授，入选国家高层次青年人才计划和中国科协青年人才托举工程。主要从事基于人工结构的物态调控及应用研究：通过设计人工微纳结构和拓扑电路网络，揭示并实现多种新奇拓扑物态；借鉴拓扑物态独特性质，开发新型功能化光电器件。以第一/通讯作者身份，在Nat. Commun. (9篇)，Phys. Rev. Lett. (6篇)，Adv. Mat., Light: Sci. & Appl., Sci. Bull.等期刊发表论文50余篇，6篇入选 ESI 高被引论文。