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**Metasurfaces at Terahertz: Communications, Sensing and Invisibility
Cloaks**
Miguel Beruete
Antennas Group-TERALAB Universidad Pública de Navarra, Campus Arrosadía,
31006 Pamplona, Spain
Multispectral Biosensing Group Navarrabiomed Complejo Hospitalario de Navarra
(CHN) Universidad Pública de Navarra (UPNA) IdiSNA. Irunlarrea 3, 31008
Pamplona, Navarra, Spain
Institute of Smart Cities (ISC), Public University of Navarra, 31006 Pamplona,
Spain
[miguel.beruete@unavarra.es](mailto:miguel.beruete@unavarra.es)
Metasurfaces are screens engineered to manipulate light in exotic and
unconventional ways. They are the latest evolution of metamaterials and like
them, are made of small metallic or dielectric pieces, called unit cells,
whose shape and arrangement govern the response of the device in a very
compact structure, ideally a single layer. Metasurfaces are nowadays under
intense research in electromagnetics and currently have given rise to
disruptive devices such as planar lenses, beam-steerers, beam-splitters,
polarizers, reaching even exotic performances like hologram generators,
invisibility cloaks, sensors, etc., all along the electromagnetic spectrum,
from microwaves to the ultraviolet [1,2].
Although they are being investigated all along the electromagnetic spectrum,
metasurfaces are being crucial in the technological development of the
terahertz (THz) band. This range between microwaves and infrared has remained
elusive until recently, due to the intrinsic difficulties in generating and
detecting this radiation. However, in the last decades a new surge of interest
has emerged due to the discovery of novel transmitters and receivers in this
band. Metasurfaces are helping to bridge the technological gap at THz, giving
rise to devices able to manipulate the THz beam in a compact footprint and
with the possibility of achieving multifunctional operation.
In this talk, I will summarize some of our most recent and provocative results
related with THz metasurfaces. I will show communication devices such as
compact metalenses [3]; a metasurface able to hide an object on the ground
acting effectively as an invisibility cloak [4]; and our latest advances on
THz sensing using metasurfaces with intricate shape, so called metageometries
[5,6].
**References**
1\. S. B. Glybovski, S. A. Tretyakov, P. A. Belov, Y. S. Kivshar, and C. R.
Simovski, "Metasurfaces: From microwaves to visible," Phys. Rep. **634** ,
1–72 (2016).
2\. K. Huang, F. Qin, H. Liu, H. Ye, C. W. Qiu, M. Hong, B. Luk’yanchuk,
and J. Teng, "Planar Diffractive Lenses: Fundamentals, Functionalities, and
Applications," Adv. Mater. **30** , 1–22 (2018).
3\. V. Pacheco-Peña, N. Engheta, S. A. Kuznetsov, A. Gentselev, and M.
Beruete, "Experimental Realization of an Epsilon-Near-Zero Graded-Index
Metalens at Terahertz Frequencies," Phys. Rev. Appl. **8** , 034036 (2017).
4\. B. Orazbayev, N. Mohammadi Estakhri, A. Alù, and M. Beruete,
"Experimental Demonstration of Metasurface-Based Ultrathin Carpet Cloaks for
Millimeter Waves," Adv. Opt. Mater. **5** , 1600606 (2017).
5\. I. Jáuregui-López, P. Rodríguez-Ulibarri, A. Urrutia, S. A. Kuznetsov,
and M. Beruete, "Labyrinth Metasurface Absorber for Ultra-High-Sensitivity
Terahertz Thin Film Sensing," Phys. status solidi - Rapid Res. Lett. **12** ,
1800375 (2018).
6\. I. Jáuregui-López, P. Rodríguez-Ulibarri, S. A. Kuznetsov, C. Quemada,
and M. Beruete, "Labyrinth Metasurface for Biosensing Applications: Numerical
Study on the New Paradigm of Metageometries," Sensors **19** , 4396 (2019).
**Host:** R. Hillenbrand