Polariton-induced transparency in hybrid 2D-material hetero-nanostructure with multi-functions

In this work, we theoretically investigate the polariton-induced transparency (PoIT) phenomenon based on a hetero-nanostructure that possesses hybrid two-dimensional (2D) materials. The hetero-nanostructure consists of periodic hexagonal boron nitride (hBN) and graphene nanoribbons that are separated by a dielectric spacer. Consequently, the near-field coupling between hyperbolic phonon-polaritonic resonances on hBN ribbons and localized surface plasmon resonances on graphene ribbons leads to a transparent window in the mid-infrared region, where strong phase dispersion as well as slow light effect exist. Such hybrid-polariton induced transparency is dominated by electric dipole, and possesses reciprocity. It can be passively tailored by changing structural parameters, and actively tuned by shifting graphene Fermi level. Meanwhile, it is insensitive to the incident angle within a wider range, and rotating polarization angle of the incident wave leads to the excitation of edge phonon polaritons, which enriches the adjustability of this heterostructure. Furthermore, it can serve as a mid-infrared sensor to detect surrounding refractive index change, gas concentration, and molecular fingerprints. And introducing a metal reflector can easily turn it to be a wide-angle dual-band light absorber. Finally, we investigate the near-omnidirectional PoIT and polarization-dependent PoIT in the extended bilayer metasurface. This work has potential mid-infrared multifunctional applications in low-dimensional hybrid-polaritonic nanodevices for phase manipulation, slow light, sensing, and absorption.