Enhanced optical chirality with directional emission of Surface Plasmon Polaritons for chiral sensing applications

Abstract

Chirality is a crucial aspect in life sciences, where systems capable of enhancing the chiroptical properties of molecules are highly demanded. In this work, we present a numerical proof of concept of a novel approach towards chiral sensing, consisting in the measurement of chiroptical properties via the directional emission of Surface Plasmon Polaritons (SPPs) on a metasurface. Based on the enhanced differential absorption between right and left circularly polarized light upon interaction with a metasurface made of high refractive index dielectric unit cells, a polarization-dependent SPP differential emission is obtained. Furthermore, the plasmonic emission direction is entirely dependent on the polarization handedness. Using FDTD numerical methods we report Circular Dichroism signals of around -6° for the unit cell, with threefold dissymmetry factor enhancements in places accessible to analytes. We believe that this work sets a brand-new branch in chiral sensing towards faster, real-time measurements.