title: Active Chiral Plasmonics.
abstract: Active control over the handedness of a chiral metamaterial has the potential to serve as key element for highly integrated polarization engineering approaches, polarization sensitive imaging devices, and stereo display technologies. However, this is hard to achieve as it seemingly involves the reconfiguration of the metamolecule from a left-handed into a right-handed enantiomer and vice versa. This type of mechanical actuation is intricate and usually neither monolithically realizable nor viable for high-speed applications. Here, enabled by the phase change material Ge3Sb2Te6 (GST-326), we demonstrate a tunable and switchable mid-infrared plasmonic chiral metamaterial in a proof-of-concept experiment. A large tunability range of the circular dichroism response from λ = 4.15 to 4.90 μm is achieved, and we experimentally demonstrate that the combination of a passive bias-type chiral layer with the active chiral metamaterial allows for switchable chirality, that is, the reversal of the circular dichroism sign, in a fully planar, layered design without the need for geometrical reconfiguration. Because phase change materials can be electrically and optically switched, our designs may open up a path for highly integrated mid-IR polarization engineering devices that can be modulated on ultrafast time scales.
authors.affiliation: †4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70550, Stuttgart, Germany.|§Max Planck Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart, Germany.
authors.forename: Xinghui
authors.initials: X
authors.lastname: Yin
authors.affiliation: †4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schäferling
authors.affiliation: ‡I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany.
authors.forename: Ann-Katrin U
authors.initials: AK
authors.lastname: Michel
authors.affiliation: †4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Tittl
authors.affiliation: ‡I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wuttig
authors.affiliation: ‡I. Institute of Physics (IA), RWTH Aachen University, 52056, Aachen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Taubner
authors.affiliation: †4th Physics Institute and Research Center SCoPE, University of Stuttgart, 70550, Stuttgart, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Giessen
keywords: Switchable; chirality; metamaterial; phase change material; plasmonic; tunable