X-shaped chiral plasmonic nanostructured metasurfaces: A numerical study

摘要

In this paper, the author reports a numerical investigation of spectroscopic circular dichroism (CD) properties, near-field enhancement, and optical chirality near a chiral plasmonic nanostructured metasurface. The individual constituents of the metasurface consist of periodic X-shaped Au nanostructures on a glass substrate. The nanostructure is made of two overlapping nanorods, including one vertical nanorod and one tilted nanorod. Strong CD of the metasurface was observed and tunable upon rotation of the individual nanorods due to geometrical symmetry breaking. Near-field enhancement of up to 5 times and a large local optical chirality were found at a plane 20 nm above the X-shaped nanostructure. Electromagnetic modeling analysis provides valuable guidelines for designing alternative two-dimensional chiral metamaterials that have potential applications for enhanced molecule and chiral plasmon interaction.