Intrinsic Superchirality in Planar Plasmonic Metasurfaces.

Plasmonic metasurfaces with spatial symmetry breaking are crucial materials with significant applications in fields such as polarization-controlled photonic devices and nanophotonic platforms for chiral sensing. In this paper, we introduce planar plasmonic metasurfaces, less than one-tenth of a wavelength thick, featuring nanocavities formed by three equilateral triangles. This configuration creates uniform, thin metasurfaces. Through a combination of experimental measurements and numerical modeling, we demonstrate the inherent superchirality of these plasmonic metasurfaces. We address the challenge of achieving a strong enhancement of optical chirality in the visible spectrum, reaching levels comparable to those of 3D chiral metasurfaces.