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

• Published in: Journal of quantitative spectroscopy & radiative transfer 2022-07, Vol.284, p.108166, Article 108166
• Main Authors: Serrera, Guillermo, González-Colsa, Javier, Giannini, Vincenzo, Saiz, José M., Albella, Pablo
• Format: Article
• Language: English
• Subjects: All-Dielectric Metasurface; Enhanced Chirality; Nanoantenna; Plasmon; Sensing
• ISSN: 0022-4073; 1879-1352
• DOI: 10.1016/j.jqsrt.2022.108166

•A novel low-loss HRI chiral nanoantenna is designed for chiral sensing.•Strong far field CD signal and high dissymmetry factor in large accessible areas.•Selective polarization-dependent unidirectional SPPs used as sensing mechanism.•Combined CD signal – SPP emission by unit cell Mie modes and grating matching.•Chiral samples are analyzed based on its Left-Right Plasmon differential absorption. 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.