Graphene, plasmons and transformation optics

Huidobro, Paloma A.; Kraft, Matthias; Ren, Kun; Maier, Stefan A.; Pendry, J. B.

doi:10.1088/2040-8978/18/4/044024

Cited by 39 publications

(62 citation statements)

References 45 publications

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“…Hence, it relates a simple flat and homogeneously biased graphene sheet in z-space to a periodically biased graphene monolayer in w-space. 28 In the above equation, γ is a scaling factor that yields the periodicity in z-space, w 0 represents the modulation strength and y 0 = w 0 e 2b −w 2 0 , where b is a parameter that represents the position of the graphene layer in the wspace. Figure 1(b) shows the conductivity modulation profile derived from the conformal transformation for different modulation strengths (plotted with solid lines).…”

Section: Graphene With 1d Conductivity Modulationmentioning

confidence: 99%

“…Hence, it relates a simple flat and homogeneously biased graphene sheet in z-space to a periodically biased graphene monolayer in w-space. 28 In the above equation, γ is a scaling factor that yields the periodicity in z-space, w 0 represents the modulation strength and y 0 = 2, with {a 0 , a 1 } given by the Fourier expansion coefficients of the transformation 3. Hence, even though our analytical model in principle applies to conductivity modulations derived from the conformal transformation, it accurately describes the simple sinusoidal modulations given in Eq.…”

Section: Graphene With 1d Conductivity Modulationmentioning

confidence: 99%

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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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Section: Graphene With 1d Conductivity Modulationmentioning

confidence: 99%

“…Hence, it relates a simple flat and homogeneously biased graphene sheet in z-space to a periodically biased graphene monolayer in w-space. 28 In the above equation, γ is a scaling factor that yields the periodicity in z-space, w 0 represents the modulation strength and y 0 = 2, with {a 0 , a 1 } given by the Fourier expansion coefficients of the transformation 3. Hence, even though our analytical model in principle applies to conductivity modulations derived from the conformal transformation, it accurately describes the simple sinusoidal modulations given in Eq.…”

Section: Graphene With 1d Conductivity Modulationmentioning

confidence: 99%

Graphene as a Tunable Anisotropic or Isotropic Plasmonic Metasurface

et al. 2016

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“…We start by considering a plasmonic metasurface based on a graphene monolayer with spatially periodic conductivity [24,25]. The configuration we propose is sketched in Figure 1a.…”

Section: Introductionmentioning

confidence: 99%

“…Here, l and s are the chemical potential and the scattering time for electrons, respectively, with s ¼ ml=ev 2 F (m is the mobility and v F % 10 6 m/s the Fermi velocity). In this work, we use the parameters a = 76 GHz/X and c g = 1.5 THz, which correspond to l = 0.65 eV and m = 10 4 cm 2 /V s. The conductivity grating established via periodic doping allows for free space radiation to couple into the surface plasmons sustained by the graphene layer, which have much shorter wavelength [24][25][26][27][28][29][30][31][32][33][34]. Hence, the modulation period needs to be much smaller than the wavelength of incident radiation (k 0 ) 2pc).…”

Section: Introductionmentioning

confidence: 99%

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Tunable plasmonic metasurface for perfect absorption

Huidobro

Maier

Pendry

2017

EPJ Applied Metamaterials

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-Tunable metasurfaces, whose functionality can be dynamically modified, open up the possibility of ultracompact photonic components with reconfigurable applications. Here we consider a graphene monolayer subject to a spatially periodic gate bias, which, thank to surface plasmons in the graphene, acts as a tunable and extremely compact metasurface for terahertz radiation. After characterizing its functionality, we show that it serves as the basic building block of an ultrathin complete absorber. In this subwavelength-thickness device, transmission and reflection channels are blocked and electromagnetic energy is completely absorbed by the metasurface building blocks. The proposed structure can be used as a modulator, and its frequency of operation can be changed by scaling its size or adjusting the doping level.

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Graphene Plasmonics: A Platform for 2D Optics

Fan

Shen

Zhang

et al. 2018

Advanced Optical Materials

161

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2D optics is gradually emerging as a frontier in modern optics. Plasmons in graphene provide a prominent platform for 2D optics in which the light is squeezed into atomic scale. This report highlights some recent progresses in graphene plasmons toward the 2D optics. The launch, observation, and advanced manipulation of propagating graphene plasmons for 2D optical circuits are described. Representative achievements associated with graphene metasurfaces, challenges, recent progresses like photoexcited graphene metasurfaces, and the transformation optics linking 2D to bulk optics with singularity are investigated.Abstract: Two-dimensional (2D) optics is gradually emerging as the frontier in modern optics. Plasmons in graphene provide a prominent platform for two-dimensional optics in which the light is squeezed into an atomic scale. This paper highlights some recent progresses in graphene plasmons towards the 2D optics. The launching, observation, and advanced manipulations of propagating graphene plasmons for 2D optical circuits are described. Representative achievements associated with graphene metasurfaces, challenges, recent progresses like photoexcited graphene metasurfaces and transformation optics linking 2D to bulk optics with singularity are investigated.

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Graphene, plasmons and transformation optics

Cited by 39 publications

References 45 publications

Graphene as a Tunable Anisotropic or Isotropic Plasmonic Metasurface

Graphene as a Tunable Anisotropic or Isotropic Plasmonic Metasurface

Tunable plasmonic metasurface for perfect absorption

Graphene Plasmonics: A Platform for 2D Optics

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