Dual-Band Selective Circular Dichroism in Mid-Infrared Chiral Metasurfaces

Abstract

Most chiral metamaterials and metasurfaces are designed to operate in a single wavelength band and with a certain circular dichroism (CD) value. Here, mid-infrared chiral metasurface absorbers with selective CD in dual-wavelength bands are designed and demonstrated. The dual-band CD selectivity and tunability in the chiral metasurface absorbers are enabled by the unique design of a unit cell with two coupled rectangular bars. It is shown that the sign of CD in each wavelength band can be independently controlled and flipped by simply adjusting the geometric parameters, the width and the length, of the vertical rectangular bars. The mechanism of the dual-band CD selection in the chiral metasurface absorber is further revealed by studying the electric field and magnetic field distributions of the antibonding and bonding modes supported in the coupled bars under circularly polarized incident light. Furthermore, the chiral resonance wavelength can be continuously increased by scaling up the geometric parameters of the metasurface unit cell. The demonstrated results will contribute to the advance of future mid-infrared applications such as chiral molecular sensing, thermophotovoltaics, and optical communication.

Department(s)

Mechanical and Aerospace Engineering

Comments

This work was supported by the National Science Foundation (DMR-1552871, ECCS-1653032); U.S. Department of Energy (DE-AC02-06CH11357).

International Standard Serial Number (ISSN)

1094-4087

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2022 Optica, All rights reserved.

Creative Commons Licensing

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Publication Date

23 May 2022

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