Brillouin zone folding driven bound states in the continuum

• Published in: Nature communications Vol. 14; no. 1; pp. 2811 - 9
• Main Authors: Wang, Wenhao, Srivastava, Yogesh Kumar, Tan, Thomas CaiWei, Wang, Zhiming, Singh, Ranjan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.05.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 147/135; 639/624/400; 639/766/400/561; Brillouin zones; Cavities; Engineering; Euclidean space; Folding; Humanities and Social Sciences; Integrated circuits; Lattice theory; Light; Momentum; multidisciplinary; Nonlinear optics; Optics; Periodic variations; Perturbation; Q factors; Quantum computing; Radiation; Robustness; Science; Science (multidisciplinary); Symmetry
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-38367-y

Non-radiative bound states in the continuum (BICs) allow construction of resonant cavities with confined electromagnetic energy and high-quality ( Q ) factors. However, the sharp decay of the Q factor in the momentum space limits their usefulness for device applications. Here we demonstrate an approach to achieve sustainable ultrahigh Q factors by engineering Brillouin zone folding-induced BICs (BZF-BICs). All the guided modes are folded into the light cone through periodic perturbation that leads to the emergence of BZF-BICs possessing ultrahigh Q factors throughout the large, tunable momentum space. Unlike conventional BICs, BZF-BICs show perturbation-dependent dramatic enhancement of the Q factor in the entire momentum space and are robust against structural disorders. Our work provides a unique design path for BZF-BIC-based silicon metasurface cavities with extreme robustness against disorder while sustaining ultrahigh Q factors, offering potential applications in terahertz devices, nonlinear optics, quantum computing, and photonic integrated circuits. Periodic perturbations and guided mode engineering into Brillouin zone folding-induced bound states in the continuum resulted in ultrahigh Q factors that are both robust and sustainable across a broad range of tunable momentum space.