A terahertz chiral metamaterial modulator

Kindness, S. J., Almond, N. W., Michailow, W., Wei, B., Delfanazari, K., Braeuninger‐Weimer, P., Hofmann, S., Beere, H. E., Ritchie, D. A. and Degl'Innocenti, R. (2020) A terahertz chiral metamaterial modulator. Advanced Optical Materials, 8(21), 2000581. (doi: 10.1002/adom.202000581)

Abstract

Active control of chirality in artificial media such as metamaterials is fundamental in many scientific areas, ranging from research into fundamental optical phenomena to the investigation of novel materials, spectroscopy, and imaging. Precise control of the light polarization states has great importance for light‐matter interaction in chemistry and biology, as media with diverse chiral properties react differently to the incoming polarization of light. In this work an active double layer metamaterial device based on vertically stacked ring resonators is realized by integrating electrostatically tunable graphene as an active element. The device is characterized with a THz time domain spectroscopic system demonstrating an all‐electrical control of circular dichroism and optical activity at ≈2 THz, reporting a tunable ellipticity of 0.55–0.98 and >20° rotation of the plane polarization, respectively, by modifying the conductivity of graphene. Further integration with a narrow frequency quantum cascade laser emitting at ≈1.9 THz, in a crossed polarizer experimental arrangement, realizes an active amplitude modulator, hence highlighting the versatility of this approach. These results represent an important milestone for the investigation of novel concepts in optics and in several applications in the THz range, such as wireless communications and spectroscopy.

• Item Type: Articles
• Additional Information: S.J.K. acknowledges the Integrated Photonic and Electronic Systems Centre for Doctoral Training (Grant No. EP/L015455/1) for funding and support. S.J.K., N.W.A., B.W., W.M., H.E.B., and D.A.R. acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC, Grant No. EP/P021859/1, Hyper Terahertz). W.M. thanks the George and Lillian Schiff Foundation of the University of Cambridge for financial support and is grateful for the Honorary Vice‐Chancellor's Award of the Cambridge Trust. R.D. acknowledges support from the EPSRC (Grant No. EP/S019383/1) and from the Royal Society (RSG/R1/180148 – Research Grant). S.H. and P.B.‐W. acknowledge funding from the EPSRC (Grant No. EP/K016636/1). P.B.‐W. acknowledges the EPSRC Cambridge NanoDTC (Grant No. EP/G037221/1).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Delfanazari, Dr Kaveh
• Authors: Kindness, S. J., Almond, N. W., Michailow, W., Wei, B., Delfanazari, K., Braeuninger‐Weimer, P., Hofmann, S., Beere, H. E., Ritchie, D. A., and Degl'Innocenti, R.
• College/School: College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
• Journal Name: Advanced Optical Materials
• Publisher: Wiley
• ISSN: 2195-1071
• ISSN (Online): 2195-1071
• Published Online: 16 August 2020
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Advanced Optical Materials 8(21):2000581
• Publisher Policy: Reproduced under a Creative Commons license