Graphene-enabled electrically switchable radar-absorbing surfaces

Balcı, Osman; Polat, Emre Ozan; Kakenov, Nurbek; Kocabaş, Coşkun

doi:10.1038/ncomms7628

Cited by 507 publications

(306 citation statements)

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“…Integrating these thin layers with a metamaterial structure is demonstrated as a good intensity and phase tuning device in IR and THz [19][20][21][22] region. Very recently, we have demonstrated active graphene devices operating in terahertz 23 and microwave frequencies 24 . We integrated electrically tunable graphene as a tunable absorbing layer and showed that these devices can operate as a perfect intensity modulator at their resonance frequencies.…”

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confidence: 99%

Controlling phase of microwaves with active graphene surfaces

Balcı

Kakenov

Kocabaş

2017

Applied Physics Letters

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In this letter, we report a method to control reflection phase of microwaves using electrically tunable graphene devices. The device consists of mutually gated large-area graphene layers placed at a quarter-wave distance from a metallic surface. This device structure yields electrically tunable resonance absorbance and step-like phase shift around the resonance frequency when the impedance of graphene matches with the free space impedance. Electrostatic control of charge density on graphene yields an ability to control both intensity (> 50 dB) and phase (~) of the reflected electromagnetic waves with voltage. Furthermore, using the asymmetry of the doping at opposite polarity of the bias voltages, we showed bidirectional phase control with the applied voltage. We anticipate that our results will pave a new directions to control interaction of electromagnetic waves with matter for long wavelengths and could open a new avenue for microwave devices.

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confidence: 99%

Controlling phase of microwaves with active graphene surfaces

Balcı

Kakenov

Kocabaş

2017

Applied Physics Letters

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“…Due to its unique electromagnetic property, PMS was used to reduce the RCS of spiral patch antenna [13], generated SSB or QPSK modulation signal [14,15] and lowered the power spectral density (PSD) of echo scattered from PMS [16]. Besides PMS, several new techniques or materials have been proposed for the design of active RAM in the past few years, e.g., graphene-enabled electrically switchable radarabsorbing surfaces relying on electrostatic tuning of the charge density on an atomically thin graphene electrode [17], inkjet printing technology in which the volume ratio of an aqueous vehicle and nanosilver (Ag) ink mixture is adjusted to change the surface resistances [18] and semiconductor nanoparticles whose particle size and hydrogenation condition are connected with its electromagnetic characteristic [19], etc.…”

Section: Introductionmentioning

confidence: 99%

The Optimization of Switching Scheme in Multi-Layer Phase-Modulated Surface and Its Influence on Scattering Properties

Fu¹,

Hong²

2016

PIER M

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Abstract-To improve absorbing properties of phase-modulated surface (PMS), the multi-active-layer PMS composed of multiple active frequency-selective surface (AFSS) layers and one background plane is theoretically studied using time-modulation theory in this paper. The optimization of PMS's switching scheme using differential evolution (DE) algorithm is also proposed for minimizing scattering echo energy at the incident frequency. We provide analytical formulation for the scattering problem and obtain the angular scattering pattern of PMS after optimization. Simulation results indicate that the optimized switching scheme is beneficial for reducing the spatial coverage of scattering echo at incident frequency. This coverage can be further confined by the increasing number of active layers in PMS. Furthermore, it is shown that floor effect appears when the number of active layers reaches a certain value, which limits the PMS structure conversely.

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“…Recently, we have modified optical properties of single-layer and multilayer graphene [14,15]. Along these lines, optical modulators, electrochromic devices, and radar absorbing surfaces have been demonstrated [14,15]. Now, in this Letter, we apply a graphene-based supercapacitor structure to dynamically tune plasmon resonances of Ag NPs.…”

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confidence: 99%

“…Figure 1 shows schematic representation of a typical hybrid graphene-Ag NPs device. Recently, we have modified optical properties of single-layer and multilayer graphene [14,15]. Along these lines, optical modulators, electrochromic devices, and radar absorbing surfaces have been demonstrated [14,15].…”

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“…Thus, it is possible to deposit ultrathin dielectric layers with angstrom-level resolution, e.g., 0.11 nm thick Al 2 O 3 corresponding to one cycle in the ALD process [10]. Large-area and single-layer graphene samples were synthesized by chemical vapor deposition on ultra-smooth copper foil substrates (Mitsui Mining and Smelting Company, Ltd., B1-SBS); details of the synthesis can be found in our previous works [7,14,15]. The native copper oxide on the copper substrate was reduced under a H 2 flow rate of 100 sccm during the annealing step.…”

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Dynamic tuning of plasmon resonance in the visible using graphene

et al. 2016

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We report active electrical tuning of plasmon resonance of silver nanoprisms (Ag NPs) in the visible spectrum. Ag NPs are placed in close proximity to graphene which leads to additional tunable loss for the plasmon resonance. The ionic gating of graphene modifies its Fermi level from 0.2 to 1 eV, which then affects the absorption of graphene due to Pauli blocking. Plasmon resonance frequency and linewidth of Ag NPs can be reversibly shifted by 20 and 35 meV, respectively. The coupled graphene-Ag NPs system can be classically described by a damped harmonic oscillator model. Atomic layer deposition allows for controlling the graphene-Ag NP separation with atomic-level precision to optimize coupling between them. Nobel metal nanoparticles show localized surface plasmon polariton (LSPP) resonances generating strong local electromagnetic field confinement at subwavelength regions; thus, they lead to a variety of interesting applications in biosensing, spectroscopy, optics, and electronics [1][2][3][4][5][6]. Modulating plasmon resonances in the visible and infrared regions of the electromagnetic spectrum remarkably extends the scope and applicability of the metal nanoparticles and, consequently, plasmonic devices with enhanced optical properties can be realized. Size, shape, charge, dielectric environment, and composition of the nanoparticles greatly affect the plasmon resonances of the nanoparticles and, thus, provide nanoscale control of the optical signals. In particular, anisotropic gold and silver nanoparticles chemically synthesized from isotropic nanoparticles by using wet chemical methods are very attractive, since they have very sharp structural features and can outperform isotropic nanoparticles in terms of near-field enhancements, biological and chemical sensing, plasmon resonance tunability, etc. [5,7].However, dynamic tuning of plasmon resonance cannot be achieved by varying the geometry or the composition of the metal nanoparticles. Another way of tuning plasmon resonances in a reversible manner is by using external stimuli such as light, By using the electro-optic effect of lithium niobate, refractive index modulation in metal-insulator-metal resonators has yielded actively tunable color filters working in the visible spectrum [10]. Another way of active tuning of plasmon resonances is by using graphene, an atomically thick sheet of carbon atoms arranged in hexagonal lattice forming a zero-band gap semiconductor with extraordinary optical and electrical properties [11,12]. The charge density and Fermi energy of monolayer graphene can be tuned by electrostatic gating in a broad range of wavelengths; E f ħv f πn 1∕2 where E f , v f , and n are Fermi energy, Fermi velocity, and charge carrier density in graphene [13]. Therefore, it is possible to tune E f in a fully reversible and highly effective manner with applied gate voltages and, hence, the interband transitions with energies less than 2E f can be terminated due to the Pauli blocking. Thus, graphene behaves like a transparent material when the incom...

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Graphene-enabled electrically switchable radar-absorbing surfaces

Cited by 507 publications

References 58 publications

Controlling phase of microwaves with active graphene surfaces

Controlling phase of microwaves with active graphene surfaces

The Optimization of Switching Scheme in Multi-Layer Phase-Modulated Surface and Its Influence on Scattering Properties

Dynamic tuning of plasmon resonance in the visible using graphene

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