Active Chiral Plasmonics: Flexoelectric Control of Nanoscale Chirality

Abstract

The ability to electrically control the optical properties of metamaterials is an essential capability required for technological innovation. The creation of dynamic electrically tunable metamaterials in the visible and near infrared regions is important for a range of imaging and fiber optic technologies. However, current approaches require complex nanofabrication processes which are incompatible for low‐cost device production. Herein, a novel simple approach is reported for electrical control of optical properties which uses a flexoelectric dielectric element to electromechanically manipulate the form factor of a chiral nanostructure. By altering the dimensions of the chiral nanostructure, the polarization properties of light are allowed to be electrically controlled. The flexoelectric element is part of a composite metafilm that is templated onto a nanostructured polymer substrate. As the flexoelectric element does not require in situ high temperature annealing, it can be readily combined with polymer‐based substrates produced by high throughput methods. This is not the case for piezoelectric elements, routinely used in microelectromechanical (MEM) devices which require high temperature processing. Consequently, combining amorphous flexoelectric dielectrics and low‐cost polymer‐based materials provides a route to the high throughput production of electrically responsive disposable metadevices.

Chirality in Light–Matter Interaction

“…Reproduced under the terms of the CC‐BY Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0). [ 245 ] Copyright 2021, The Authors, published by Wiley‐VCH. c) A metal–dielectric–metal (MDM) structure consisting of two stacked identical nanohole arrays separated by a variable thickness silk fibroin layer.…”

“…utilizing a polymer‐based nanoelectromechanical material to manipulate the dimensions of a nanostructure based on chiral “shuriken”‐shaped indentations in a polycarbonate substrate (see Figure 6b). [ 224,245 ] A clear modification of the device geometry was observed by SEM with voltage applied to the electromechanical material (a near 30% decrease in the total arm area of the indentation). This modification led to a notable change in the measured ORD spectra.…”

“…The form factor is visibly altered in response to an applied potential on different thicknesses of the flexoelectric layer (PZT), leading to a change in the chiroptical properties. Reproduced under the terms of the CC-BY Creative Commons Attribution 4.0 International license (https://creativecommons.org/licenses/by/4.0) [245]. Copyright 2021, The Authors, published by Wiley-VCH.…”

The Beginner's Guide to Chiral Plasmonics: Mostly Harmless Theory and the Design of Large‐Area Substrates

“…[280,281] Similarly, this approach allows incorporation of flexoelectric materials to gain active control over chiroptical signals by triggering mechanical deformation upon applying an external voltage. [282] of 3D structures that can be prepared by the process, notably without any substrate rotation or glancing angle deposition. Reproduced with permission.…”

“…[280,281] Similarly, this approach allows incorporation of flexoelectric materials to gain active control over chiroptical signals by triggering mechanical deformation upon applying an external voltage. [282] Adv. Optical Mater.…”