Giant and tunable 2D-chiroptical response in few-layer borophene metasurfaces

Abstract

The 2D-chiroptical response in few-layer borophene metasurfaces (FBMs) is studied theoretically. By stacking borophene metasurfaces with the same physical parameters near the topological transition for the borophene metasurface, it is found that there exists strong 2D chirality, which can be controlled by the incident angle and the twist angle between the metasurfaces. When the borophene metasurfaces with different electron densities are stacked, the strong circular conversion dichroism (CCD) is found near the corresponding topological transition frequency for each borophene metasurface, resulting in the formation of the multiband CCD spectra. It is demonstrated that in the FBM there exists an ultrahigh sensitivity of the CCD to the substrate refractive index.