A Terahertz Chiral Metamaterial Modulator. Issue 21 (16th August 2020)

• Record Type: Journal Article
• Authors: Kindness, Stephen J.; Almond, Nikita W.; Michailow, Wladislaw; Wei, Binbin; Delfanazari, Kaveh; Braeuninger‐Weimer, Philipp; Hofmann, Stephan; Beere, Harvey E.; Ritchie, David A.; Degl'Innocenti, Riccardo
• Is Part Of: Advanced optical materials. Volume 8:Issue 21(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-08-16
• Subjects: chirality -- graphene -- metamaterials -- quantum cascade lasers -- terahertz modulators; Optical materials -- Periodicals; Photonics -- Periodicals; 620.11295
• DOI: 10.1002/adom.202000581
• Languages: English
• ISSNs: 2195-1071

Abstract

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. Abstract : A graphene loaded double layer chiral metamaterial device is realized for the active tuning of terahertz radiation. Depending on the targeted frequency range the device exhibits a continuous tuning of the optical activity or circular dichroism. The device is successfully implemented with both THz time domain spectrometer and a quantum cascade laser.