Active Tuning of Midinfrared Surface Plasmon Resonance and Its Hybridization in Black Phosphorus Sheet Array

The behaviors of anisotropic plasmons in black phosphorus have been fully exploited across a complete variety of system including individual nanoribbon, vertically offset paired ones, and nanoribbon/sheet hybrid system. Benefiting from its two-dimensional nature, plasmons can be actively controlled by either geometrical parameters or the carrier doping in black phosphorus, which allows for the emerging phenomenon of strong light–matter interaction at mid-infrared region. Remarkably, Rabi splitting over 17.3 meV is observed in the plasmonic spectra of the nanoribbon/sheet hybrid structure as harnessed by the strong interaction of coupled plasmons. We also propose a scheme that supports plasmon on a continuous monolayer black phosphorus by using a diffraction grating. By adjusting the geometrical parameters of the grating and the Fermi level of the black phosphorus slightly, the resonance wavelength can be changed notably. The results appealing open up possibilities of devising black phosphorus-based plasmons in the application of optical detection and sensing within the deep subwavelength regime at mid-infrared region.