Photonic-Plasmonic Hybrid Nanocavity for Quasi-Bound States in the Continuum at Telecom Wavelengths

Recent advances in bound states in the continuum (BICs) are closely associated with optically induced Mie and Fabry-Perot resonances in the dielectric supercavity, featuring with suppressed radiative losses and strong light confinement. In order to break the diffraction limit and achieve large-scale optoelectronic integration, we propose a novel photonic-plasmonic hybrid nanocavity to manipulate the mode hybridization arising from the inter-coupling between the photonic and plasmonic Mie-like resonances. The regime of quasi-BIC modes can be achieved via the tuning of the inner radius of the Au split-ring or the position of the Si cylinder instead of the dimensional aspect ratio. In contrast to the previously individual or arrayed nanostructures, we integrate the proposed nanocavity with the Si waveguides to construct a hybrid circuit, which could support both inspiration and transmission of optical quasi-BIC signals totally on chip. Our photonic-plasmonic hybrid configuration represents a typical example of the development of novel BIC-inspired optical cavities, paving the way for its applications in the fields of nanophotonics and meta-optics.