How good would the conductivity of graphene have to be to make single-layer-graphene metamaterials for terahertz frequencies feasible?

Zouaghi, Wissem; Voß, Daniel; Gorath, Moritz; Nicoloso, N.; Roskos, Hartmut G.

doi:10.1016/j.carbon.2015.06.077

Cited by 45 publications

(23 citation statements)

References 39 publications

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“…The latter, even if characterized by a loss tangent greater by an order of magnitude with respect to that of Zeonor, is particularly amenable for the realization of graphene-based structures. Indeed, graphene, when transferred on SiO 2 , shows limited phonon scattering [48], an effect that heavily contributes to decreasing the quality of graphene during its synthesis (see [49] for further details).…”

Section: Thz Materialsmentioning

confidence: 99%

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Terahertz Leaky-Wave Antennas Based on Metasurfaces and Tunable Materials

Fuscaldo¹,

Tofani²,

Burghignoli³

et al. 2019

Metamaterials and Metasurfaces

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Terahertz frequencies are increasingly gaining attention due to the recent efforts made in narrowing the technological gap among microwave and optical components. Still the demand of efficient THz antennas is high, due to the difficulty in obtaining directive patterns and good radiation efficiencies with planar, low-cost, easy-to-fabricate designs. In this regard, leaky-wave antennas have recently been investigated in the THz range, showing very interesting radiating features. Specifically, the combination of the leakywave antenna design with the use of metamaterials and metasurfaces seems to offer a promising platform for the development of future THz antenna technologies. In this Chapter, we focus on three different classes of leaky-wave antennas, based on either metasurfaces or tunable materials, namely graphene and nematic liquid crystals. While THz leaky-wave antennas based on homogenized metasurfaces are shown to be able to produce directive patterns with particularly good efficiencies, those based on graphene or nematic liquid crystals are shown to be able to dynamically reconfigure their radiating features. The latter property, although being extremely interesting, is obtained at the expense of an increase of costs and fabrication complexity, as it will emerge from the results of the presented study.Transformation Optics in 2006 by Pendry [2], metasurfaces have represented a privileged platform for achieving a considerable control of electromagnetic waves propagation. Electromagnetic cloaking and metasurfing, i.e., controlling surface or guided waves through tunable metasurfaces [3], are one of the most known applications of metasurfaces. However, in this Chapter, we focus on the application of metasurfaces for the realization of reconfigurable leakywave antennas (LWAs) [4].In the microwave range, there exists numerous realizations of metasurfaces (see, e.g., [4] and refs. therein), but at terahertz (THz) frequencies (nominally comprised between 300 GHz and 3 THz [5]), very few designs are available. Nowadays, THz technology is recognized as one of the most promising and challenging area of research for a twofold reason: (i) on the one hand, the wide and interdisciplinary character of THz applications, spanning from molecular spectroscopy and astrophysics, to high data rate communications and high-resolution imaging, passing through security screening and drug detection [6]; (ii) on the other hand, the increasing availability of efficient THz sensors and sources [7] that have recently contributed to considerably narrow the so-called THz gap.Nevertheless, the demand of efficient THz antennas is still high [6]. Indeed, even though various solutions have been proposed (see, e.g., [8][9][10][11]), efficient realizations often require high fabrication costs and complexity [11]. To better handle the efficiency vs. cost/complexity tradeoff, leaky-wave antennas [12] have been proposed and experimentally demonstrated as valid alternatives for the design of efficient, low-cost, THz antennas [13,14]. Such prototypes...

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Section: Thz Materialsmentioning

confidence: 99%

“…As a consequence, the relaxation time τ is never known a priori. The interested reader can refer to the recent detailed survey proposed in[49] as well as discussions in[20,21].Terahertz Leaky-Wave Antennas Based on Metasurfaces and Tunable Materials http://dx.doi.org/10.5772/intechopen.78939…”

mentioning

confidence: 99%

Terahertz Leaky-Wave Antennas Based on Metasurfaces and Tunable Materials

Fuscaldo¹,

Tofani²,

Burghignoli³

et al. 2019

Metamaterials and Metasurfaces

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“…The relaxation time of graphene is one of the most fundamental quantities, which is related to the electron scattering rate and the Fermi energy level of graphene. In this part, we analyze the antenna performance and equivalent circuit parameters with several typical and widely used relaxation time values, from 0.1 ps [12], 0.2 ps [33], to 0.5 ps [24,34]. The listed values were carefully chosen to be approximately the same as the realistic values measured in experimental work.…”

Section: Relaxation Timementioning

confidence: 99%

Equivalent Resonant Circuit Modeling of a Graphene-Based Bowtie Antenna

Zhang

Liu

et al. 2018

Electronics

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The resonance performance analysis of graphene antennas is a challenging problem for full-wave electromagnetic simulators due to the trade-off between the computer resource and the accuracy of results. In this paper, an equivalent circuit model is presented to provide a concise and fast way to analyze the graphene-based THz bowtie antenna. Based on the simulated results of the frequency responses of the antenna, a suitable equivalent circuit of Resistor-Inductor-Capacitor (RLC) series is proposed to describe the antenna. Then the RLC parameters are extracted by considering the graphene bowtie antenna as a one-port resonator. Parametric analyses, including chemical potential, arm length, relaxation time, and substrate thickness, are presented based on the proposed equivalent circuit model. Antenna input resistance R is a significant parameter in this model. Validation is performed by comparing the calculated R values with the ones from full-wave simulation. By applying different parameters to the graphene bowtie antenna, a set of R, L, and C values are obtained and analyzed comprehensively. A very good agreement is observed between the equivalent model and the numerical simulation. This work sheds light on the graphene-based bowtie antenna’s initial design and paves the way for future research and applications.

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“…Obtaining a high conductivity by using graphene is one of the main advantage of the graphene based structures. [19,20]. Correspondingly, one can control the electromagnetic wave by controlling the conductivity (and relatedly dielectric constant) of the graphene in which it provides additional flexibility in the design and fabrication of various device configurations.…”

Section: Accepted Manuscriptmentioning

confidence: 99%