Dyadic Green’s functions and guided surface waves for a surface conductivity model of graphene

Hanson, George W.

doi:10.1063/1.2891452

Cited by 2,505 publications

(1,190 citation statements)

References 27 publications

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“…Figure 1c plots the frequency-dependent real and imaginary parts of the extracted conductivity s S for several DC biasing voltages applied between the graphene layers. In the low THz band, the real component of the sample conductivity does not vary with frequency, whereas the magnitude of the imaginary part, which facilitates the propagation of surface plasmons in this frequency band 37 , increases with frequency following a standard Drude model. Figure 2 shows the measured reconfiguration capabilities of the fabricated graphene stack at f ¼ 1.5 THz in different scenarios.…”

Section: Resultsmentioning

confidence: 99%

Self-biased reconfigurable graphene stacks for terahertz plasmonics

et al. 2015

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The gate-controllable complex conductivity of graphene offers unprecedented opportunities for reconfigurable plasmonics at terahertz and mid-infrared frequencies. However, the requirement of a gating electrode close to graphene and the single 'control knob' that this approach offers limits the practical implementation and performance of these devices. Here we report on graphene stacks composed of two or more graphene monolayers separated by electrically thin dielectrics and present a simple and rigorous theoretical framework for their characterization. In a first implementation, two graphene layers gate each other, thereby behaving as a controllable single equivalent layer but without any additional gating structure. Second, we show that adding an additional gate allows independent control of the complex conductivity of each layer within the stack and provides enhanced control on the stack equivalent complex conductivity. These results are very promising for the development of THz and mid-infrared plasmonic devices with enhanced performance and reconfiguration capabilities.

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Section: Resultsmentioning

confidence: 99%

Self-biased reconfigurable graphene stacks for terahertz plasmonics

et al. 2015

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“…Because of the two-dimensional (2D) nature of this material, the surface plasmons it supports have very short wavelengths and exhibit extreme out-of-plane confinement to the sheet, as has already been demonstrated in a number of experiments. [3][4][5][6][7][8][9][10][11] Compared to the noble metals commonly employed for plasmonics, 12 graphene has a low carrier concentration, and, for this reason, plasmons in graphene are relatively long-lived and appear at lower frequencies. While the plasmonic response of metals is weak at the infrared or lower frequencies, graphene plasmons exist in the THz regime with relatively low losses.…”

Section: Introductionmentioning

confidence: 99%

Graphene as a Tunable Anisotropic or Isotropic Plasmonic Metasurface

et al. 2016

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We demonstrate a tunable plasmonic metasurface by considering a graphene sheet subject to a periodically patterned doping level. The unique optical properties of graphene result in electrically tunable plasmons that allow for extreme confinement of electromagnetic energy in the technologically significant regime of THz frequencies.Here we add an extra degree of freedom by using graphene as a metasurface, proposing to dope it with an electrical gate patterned in the micron or sub-micron scale. By extracting the effective conductivity of the sheet we characterize metasurfaces periodically modulated along one or two directions. In the first case, and making use of the analytical insight provided by transformation optics, we show an efficient control of THz radiation for one polarization. In the second case, we demonstrate a metasurface with an isotropic response that is independent of wave polarization and orientation.Graphene, an atomically-thin layer of carbon atoms arranged in a honeycomb lattice, features outstanding mechanical, thermal and electrical properties. 1 Its characteristic linear * To whom correspondence should be addressed 1 dispersion for electrons close to the Dirac point results in the possibility of tuning the carrier concentration by external means. 2 In particular, graphene can be biased by electrical gating or surface doping, which modifies its Fermi level and permits the existence of surface plasmons propagating along graphene. Because of the two-dimensional (2D) nature of this material, the surface plasmons it supports have very short wavelengths and exhibit extreme out-of-plane confinement to the sheet, as has already been demonstrated in a number of experiments. [3][4][5][6][7][8][9][10][11] Compared to the noble metals commonly employed for plasmonics, 12 graphene has a low carrier concentration, and, for this reason, plasmons in graphene are relatively long-lived and appear at lower frequencies. While the plasmonic response of metals is weak at the infrared or lower frequencies, graphene plasmons exist in the THz regime with relatively low losses. 13-15 These facts, added to the important ingredient of tunability, make graphene a very suitable platform for the design of plasmonic metasurfaces in the THz regime. 16,17 Metasurfaces, the 2D counterpart of metamaterials, 18,19 consist of a planar arrangement of resonant subwavelength-sized building blocks. 20 By appropriately designing the blocks and their arrangement, metasurfaces provide an ultra-thin platform for manipulating electromagnetic (EM) waves. Novel phenomena and applications based on metasurfaces range from broadband light bending and anomalous reflection and refraction 21-23 to strong spin-orbit interactions of light. 24In this work, we study graphene as a plasmonic metasurface that offers the potential to control radiation in the THz regime. Different from previous studies, 16,17 which focused on patterning the graphene, here we consider a continuous graphene sheet with periodically modulated doping. This gives rise ...

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“…The absorption of graphene is usually derived from its 2D complex optical conductivity # ( , , , ), calculated from the Kubo formula [23,24]. It includes interband and intraband absorption and depends on the light angular frequency ω, chemical potential µ c , charged particle scattering rate Γ, and temperature T. The complex permittivity can be calculated from the optical conductivity as # = .…”

Section: Design and Fabrication Of Graphene Modulatormentioning

confidence: 99%

Broadband 10 Gb/s operation of graphene electro‐absorption modulator on silicon

Pantouvaki

Campenhout

et al. 2016

Laser & Photonics Reviews

162

156

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High performance integrated optical modulators are highly desired for future optical interconnects. The ultra-high bandwidth and broadband operation potentially offered by graphene based electro-absorption modulators has attracted a lot of attention in the photonics community recently. In this work, we theoretically evaluate the true potential of such modulators and illustrate this with experimental results for a silicon integrated graphene optical electro-absorption modulator capable of broadband 10 Gb/s modulation speed. The measured results agree very well with theoretical predictions. A low insertion loss of 3.8 dB at 1580 nm and a low drive voltage of 2.5 V combined with broadband and athermal operation were obtained for a 50 µm-length hybrid graphene-Si device. The peak modulation efficiency of the device is 1.5 dB/V. This robust device is challenging best-in-class Si (Ge) modulators for future chip-level optical interconnects.

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Dyadic Green’s functions and guided surface waves for a surface conductivity model of graphene

Cited by 2,505 publications

References 27 publications

Self-biased reconfigurable graphene stacks for terahertz plasmonics

Self-biased reconfigurable graphene stacks for terahertz plasmonics

Graphene as a Tunable Anisotropic or Isotropic Plasmonic Metasurface

Broadband 10 Gb/s operation of graphene electro‐absorption modulator on silicon

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