Chiral Metasurfaces with Maximum Circular Dichroism Enabled by Out‐of‐Plane Plasmonic System

Abstract

Chiral metasurfaces with pronounced reflective chiroptical responses have drawn extensive attention as they can offer great opportunities for various chirality-related applications. However, their fascinating potential are restrained by limited chiroptical responses, relatively complex design principle, and fabrication strategy. Herein, a concise and general design principle to develop out-of-plane reflective chiral metasurfaces, empowered with the maximum theoretical circular dichroism (CD), is theoretically proposed and experimentally demonstrated. The designed out-of-plane chiral metasurfaces operating in the terahertz (THz) region are flexibly fabricated via a simple, scalable, low-cost and lithography-free fabrication strategy by integrating a three-dimensional (3D) printing technique. Finally, the methodological stabilities and the strong chiroptical responses of proposed chiral metasurfaces are validated experimentally. From the general design principle, simple fabrication strategy as well as maximum chiroptical responses of proposed reflective chiral metasurfaces, it can be envisaged that these findings may overcome the difficulties in design, optimization, and fabrication for reflective chiral metasurfaces and provide promising potentials for various chirality-related applications in emerging THz technologies, such as chiral sensing, imaging, spectroscopy and polarimetry.

Dielectric chiral metasurfaces for enhanced circular dichroism spectroscopy at near infrared regime

“…In recent years, many chiral metasurfaces were presented in the literature based on plasmonic structures to enhance lightmatter interaction. [27][28][29][30] However, the ohmic losses, enhancement of just electric dipoles, and suppression of higher-order multipolar resonances in such structures at optical wavelengths limit their potential applicability. The technology trend shied towards high refractive index dielectric nanostructures to mitigate these limitations to enhance the light-matter interaction in near and far-eld at the nanoscale.…”

“…Furthermore, several groups have presented planar and multilayer dielectric chiral metasurfaces for strong chiro-optical responses based on chiral, achiral, and cascaded geometries. 30,31,[35][36][37][38] Initially, conventional chiral geometries are demonstrated to achieve strong CD at the selected wavelengths in the infrared regime. 30,35 Then, multilayer chiral metasurfaces were presented for broadband chiro-optical responses based on achiral nanostructures.…”

“…30,31,[35][36][37][38] Initially, conventional chiral geometries are demonstrated to achieve strong CD at the selected wavelengths in the infrared regime. 30,35 Then, multilayer chiral metasurfaces were presented for broadband chiro-optical responses based on achiral nanostructures. 36 Meanwhile, planar metasurfaces are also demonstrated based on disks-type structures and cascaded chiral and achiral geometries using nano-rods to achieve signicant chiro-optical responses.…”

Capacitive Enhancements of the Chiroptical Response in Plasmonic Helicoids

“…The size of the chiral MIM structures as a function of resonance wavelength. [ 14–17,12,44–46 ] Reproduced with permission. [ 12 ] Copyright 2007, The Optical Society.…”

“…Reproduced with permission. [ 44 ] Copyright 2022, John Wiley & Sons, Inc. Reprodued with permission. [ 45 ] Copyright 2012, American Physical Society.…”