Abstract-Dielectric Resonator Reflectarray as High-Efficiency Nonuniform Terahertz Metasurface

Daniel Headland*†, Eduardo Carrasco‡¶, Shruti Nirantar§∥, Withawat Withayachumnankul†⊥, Philipp Gutruf§∥,James Schwarz§∥, Derek Abbott†, Madhu Bhaskaran§∥, Sharath Sriram§∥, Julien Perruisseau-Carrier‡, and Christophe Fumeaux†

† School of Electrical and Electronic Engineering, The University of Adelaide, Adelaide, SA 5005, Australia

‡ École Polytechnique Fédérale de Lausanne, EPFL, 1015 Lausanne, Switzerland

¶ Foundation for Research on Information Technologies in Society, IT’IS, 8004 Zürich, Switzerland

§Functional Materials and Microsystems Research Group and ∥MicroNano Research Facility, RMIT University, Melbourne, Victoria 3000, Australia

⊥ Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8550, Japan

ACS Photonics, Article ASAP

DOI: 10.1021/acsphotonics.6b00102

Publication Date (Web): May 13, 2016

Copyright © 2016 American Chemical Society

*E-mail: daniel.headland@adelaide.edu.au.

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.6b00102

Advances in terahertz technology rely on the combination of novel materials and designs. As new devices are demonstrated to address the terahertz gap, the ability to perform high-efficiency beam control will be integral to making terahertz radiation a practical technology. Here, we use a metasurface composed of nonuniform dielectric resonator antennas on a ground plane to achieve efficient beam focusing at 1 THz. The dielectric resonators are made of high-resistivity silicon, which is a low-loss, nondispersive material for terahertz waves. The resonators operate around the resonance of the displacement current in the silicon, which is crucial to attaining high efficiency. The reflectarray’s capacity to focus terahertz radiation is experimentally verified, and hence by the principle of antenna reciprocity, it can also be employed as a terahertz collimator. The demonstrated device can therefore be deployed for high-gain terahertz antennas. Further measurements show that the loss of the reflectarray is negligible, which confirms the high efficiency of the dielectric resonators. This finding will enable the design of efficient flat-profile terahertz reflectarrays and metasurfaces to serve arbitrary beam control requirements in the near and far fields.

Abstract-Dielectric resonator reflectarray as high-efficiency non-uniform terahertz metasurface

Daniel Headland, Eduardo Carrasco, Shruti Nirantar, Withawat Withayachumnankul, Philipp Gutruf, James Schwarz, Derek Abbott, Madhu Bhaskaran, Sharath Sriram, Julien Perruisseau-Carrier, and Christophe Fumeaux

ACS Photonics, Just Accepted Manuscript

DOI: 10.1021/acsphotonics.6b00102

Publication Date (Web): May 13, 2016

Copyright © 2016 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.6b00102

Abstract

Advances in terahertz technology rely on the combination of novel materials and designs. As new devices are demonstrated to address the terahertz gap, the ability to perform high-efficiency beam control will be integral to making terahertz a practical technology. Here, we use a metasurface composed of nonuniform dielectric resonator antennas on a ground plane to achieve efficient beam focusing at 1 THz. The dielectric resonators are made of high-resistivity silicon, which is a low-loss, non-dispersive material for terahertz waves. The resonators operate around the resonance of displacement current in the silicon, which is crucial to attaining high-efficiency. The reflectarray’s capacity to focus terahertz radiation is experimentally verified, and hence by the principle of antenna reciprocity, it can also be employed as a terahertz collimator. The demonstrated device can therefore be deployed for high-gain terahertz antennas. Further measurements show that the loss of the reflectarray is negligible, which confirms the high efficiency of the dielectric resonators. This finding will enable the design of efficient flat-profile terahertz reflectarrays and metasurfaces to serve arbitrary beam control requirements in the near- and far-field.

Abstract-Near optimal graphene terahertz non-reciprocal isolator

• Michele Tamagnone,
• Clara Moldovan,
• Jean-Marie Poumirol,
• Alexey B. Kuzmenko,
• Adrian M. Ionescu,
• Juan R. Mosig
• & Julien Perruisseau-Carrier

http://www.nature.com/ncomms/2016/160406/ncomms11216/abs/ncomms11216.html

Isolators, or optical diodes, are devices enabling unidirectional light propagation by using non-reciprocal optical materials, namely materials able to break Lorentz reciprocity. The realization of isolators at terahertz frequencies is a very important open challenge made difficult by the intrinsically lossy propagation of terahertz radiation in current non-reciprocal materials. Here we report the design, fabrication and measurement of a terahertz non-reciprocal isolator for circularly polarized waves based on magnetostatically biased monolayer graphene, operating in reflection. The device exploits the non-reciprocal optical conductivity of graphene and, in spite of its simple design, it exhibits almost 20 dB of isolation and only 7.5 dB of insertion loss at 2.9 THz. Operation with linearly polarized light can be achieved using quarter-wave plates as polarization converters. These results demonstrate the superiority of graphene with respect to currently used terahertz non-reciprocal materials and pave the way to a novel class of optimal non-reciprocal devices.