Graphenebased tunable hyperbolic metamaterials and. Figure 1 illustrates our approach to fabricate the doublelayer graphene optical modulator. Introduction light absorption in thin films has always been a relevant topic in optics, especially from the application point of view. We make use of transformation optics 29 32 to derive the optical spectrum of such gratings within the quasistatic approximation, study their plasmonic response. Design of an ultrawideband antenna using flexible graphenebased conductor sheets. Active spatial control of terahertz plasmons in graphene. May, 2010 flexible transformation plasmonics using graphene. He has been a visiting scientist during 20062008 and a visiting professor during 202014 with the research laboratory of electronics at massachusetts institute of technology, usa. Such radiative loss is typically dependent on the radius of curvature of the bump. Graphene, plasmons and transformation optics request pdf. Electrically tunable damping of plasmonic resonances with. A new strategy to control the flow of surface plasmon polaritons at metallic surfaces is presented. Beyond optics, martin wegener takes us from using to to improve solar cell efficiency to transformation mechanics, showing how mechanical cloaks can improve the utility of scaffolds.
Freespace carpet cloak using transformation optics and graphene. Freespace carpet cloak designed with transformation optics requires materials exhibiting simultaneously anisotropic properties and plasmalike behaviors, but materials that simultaneously meet these requirements are rarely found in nature. Transformation optics asks, using maxwells equations, what kind of electromagnetic medium recreates some smooth deformation of space. Here, we add an extra degree of freedom by using graphene as a. This cited by count includes citations to the following articles in scholar. Such degree of freedom provides the prospect of having different patches with different conductivities on a single flake of graphene. Abstract here we theoretically show, by designing and manipulating spatially inhomogeneous, non. Metamaterials and transformation optics play substantial roles in various branches of optical science and engineering by providing schemes to tailor. Lee1, choongi choi2, sungyool choi4, xiang zhang3,5 and bumki min1 the extraordinary electronic properties of graphene provided. Pdf document this is an authorcreated, uncopyedited version of an article accepted for publication in journal of optics. In this paper, we will show how surface conductivity. Transformation optics using graphene 5 optical properties of graphene.
Europe pmc is an archive of life sciences journal literature. Transformation optics using graphene science, 3326035, 12911294. Metamaterial cloaking is the usage of metamaterials in an invisibility cloak. Metamaterials direct and control the propagation and transmission of specified parts of the light spectrum and demonstrate the potential to render an object seemingly invisible. Tunable graphene metasurface reflectarray for cloaking.
This approach is based on the fact that object being invisible is to be concealed behind an arti. Tuning optical responses of metallic dipole nanoantenna using. The guiding principle is einsteins principle of covariance. Graphenebased tunable hyperbolic metamaterials and enhanced near. Osa flexible transformation plasmonics using graphene.
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 media, possibly made of metamaterials, are designed such that they appear to perform a coordinate transformation from physical space to some virtual electromagnetic space. Manipulating surface plasmon waves by transformation optics. Oneatomthick ir metamaterials and transformation optics using. Unidirectional invisibility and pt symmetry withgraphene. Using graphene, the transformation optics has more potential applications in optics, such as the beam shifters, invisibility cloaks, and lenses. Osa active control of optical chirality with graphene. The ability to control the spatial variation of permittivity and permeability by electrical means would yield new perspectives on adaptive electromagnetic cloaking and.
Graphene, plasmons and transformation optics p a huidobro1, m kraft1, r kun2, s a maier1 and j b pendry1 1imperial college london, department of physics, the blackett laboratory, london sw7 2az, uk 2school of precision instrument and optoelectronics engineering, tianjin university, tianjin tianjin 300072, people. Graphene as a platform for ir metamaterials tunability of graphene conductivity is an exciting feature inhomogeneous conductivity patterns lead to ir oneatomthick transformation optics numerous optical devices can be envisioned. Xu and xiangdong zhang, optics express 19, 22999 2011. We describe the general methodology for the design of transformation optical devices for surface plasmons and analyze, for. Broadband and tunable absorbers consisting of graphene metasurface and metalbacked dielectric layer have been designed based on the formulas derived from this approach and verified. Hyperlens based on monolayer graphene and boron nitride. Engheta, transformation optics using graphene, science 3326035, 12911294 2011. Varying the graphene chemical potential by using static electric field yields a way to tune the graphene conductivity in the terahertz and infrared frequencies. Jun 10, 2011 metamaterials and transformation optics play substantial roles in various branches of optical science and engineering by providing schemes to tailor electromagnetic fields into desired spatial patterns.
In the absence of any transformation optics, the plasmon mode propagating along the graphene sheet from the far left, would su. Downloaded from transformation optics using graphene. Here we theoretically show, by designing and manipulating spatially inhomogeneous, nonuniform conductivity patterns across a single flake of graphene, that this singleatomlayered material can serve as a oneatomthick platform for infrared metamaterials and transformation optical devices. Oneatomthick ir metamaterials and transformation optics using graphene ashkan vakil and nader engheta university of pennsylvania department of electrical and systems engineering philadelphia, pennsylvania 19104, u. We compute the optical conductivity of graphene beyond the usual dirac cone approximation, giving results that are valid in the visible region of the conductivity spectrum.
Due to the aforementioned extraordinary properties of graphene, it is suitable for use in many applications, including transformation optics 15, filters 7, absorbers 8,16,17, and optical. Design of an ultrawideband antenna using flexible graphenebased conductor sheets sajid m. Zhenzhong yu, yijun feng, zhengbin wang, junming zhao, tian jiang. Tuning optical responses of metallic dipole nanoantenna using graphene xingang ren, wei e. According to, the effective refractive index of graphene has little relationship with its thickness, for saving simulation computer resource, the graphene thickness is set as 1 nm. Switching teraherz waves with gatecontrolled active graphene. Transformation optics has been shown to be a powerful tool for studying graphene 9 and as we have shown in a previous paper 8, the grating can strongly couple incident radiation to plasmons. Transformation optics has been proved to be a general methodology for taming and controlling electromagnetic waves in any desired manner 1. The former one exploits the beauty of transformation optics and stunning e. The operational characteristics angle of beam steering, focal distance, angular e ciency, losses etc. The panoramic lens is a special kind of lens, which is applied to observe full view.
Here we theoretically study oneatomthick metamaterials, oneatomthick waveguide elements, cavities, mirrors, lenses, fourier optics and finally a few case studies illustrating transformation optics on a single sheet of graphene in midinfrared wavelengths. Electrically switchable metadevices via graphene science. Ultracompact phase modulators based on graphene plasmons. Panoramic lens designed with transformation optics. In this letter, we theoretically present a panoramic lens pl using transformation optics method. Tr ansformation optics scheme for tw odimensional materials. This study presents an effective method to model, analyse and design graphene metasurfacebased terahertz thz absorbers using equivalent circuit model approach. Pdf underpinned by the advent of metamaterials, transformation optics offers. Oneatomthick optical devices based on graphene abstract metamaterials and transformation optics have received considerable attention in the recent years, as they have found an immense role in many areas of optical science and engineering by offering schemes to control electromagnetic fields. Analysis of infrared spectra with narrow band absorption by a. Transformation optics and metamaterials purdue engineering.
This ingenious application apparently is a big step toward real breakthrough of graphene optics. A planar electromagnetic black hole based on graphene. When the effective mode index of the graphene n gp is designed and changes following eq. Singlelayer graphene construction can be used to create oneatomthick optical elements. Steve cummer also assesses how the to algorithm can and has been successfully extended to other disciplines such as acoustics, elastodynamics and heat flow. Pdf susyinspired onedimensional transformation optics. Department of electrical engineering and computer science, university of california, irvine, ca, 92697, usa. Graphene disks for frequency control of terahertz waves in. Oneatomthick ir metamaterials and transformation optics. Design examples of a beam squeezer, bend, and omnidirectional absorber. The past few years have witnessed tremendous achievements.
Tunable graphene metasurface re ectarray for cloaking. It is based on the application of the concept of transformation optics to devise the optical parameters of the dielectric medium placed on top of the metal surface. Oneatomthick ir metamaterials and transformation optics using graphene. Vakil and n, engheta, transformation optics using graphene, science, vol. Tunable spatial mode converters and optical diodes for. This requirement fixes very precisely the required electromagnetic medium. Metamaterials and transformation optics play substantial roles in various branches of optical science and engineering by providing schemes to tailor electromagnetic fields into desired spatial patterns. Pdf transformation optics and metamaterials researchgate. The reflections of such structures are investigated by analytical effective medium theory combined with transfer matrix method emttmm and numerical finite element method fem.
Atomically localized plasmon enhancement in monolayer graphene. This is accomplished by manipulating the paths traversed by light through a novel optical material. Nov 01, 2015 in the practical fabrication, the hemisphere surface is composed of some graphene ribbons with fixed refractive index. Tunable metamaterial with gold and graphene splitring. The flexible control of surface plasmon polaritons spps is important and intriguing due to its wide application in novel plasmonic devices. In general, such schemes are meant to appropriately tailor the constitutive parameters of metamaterials in order to control the trajectory of light in two and three dimensions. Design of highgain lens antenna by gradientindex metamaterials using transformation optics. Invisibility studies in literature bifurcate as cloaking using transformation optics and transfer matrix methods. As we describe in this article, the concept of transformation optics embraces some of the spectacular recent applications of metamaterials.
Metamaterials and transformation optics have received considerable attention in the recent years, as they have found an immense role in many areas of optical science and engineering by offering schemes to control electromagnetic. Plasmonic cloak using graphene at infrared frequencies. Electrically tunable graphene plasmonic quasicrystal. Graphene can be used as a platform for transformationoptics devices due to its tunability of conductivity. The recently discovered graphene has shown unique anisotropic plasmalike behavior benefitting from its natural twodimensional structure and inplane. Transformation optics using graphene scholarlycommons. Department of electrical and electronic engineering, the university of hong kong, pokfulam. We report a theoretical study showing that by designing and manipulating spatially inhomogeneous, nonuniform conductivity patterns across a flake of graphene, one can have this material as a. Transformation optics using graphene ashkan vakil and nader engheta metamaterials and transformation optics play substantial roles in various branches of optical science and engineering by providing schemes to tailor electromagnetic fields into desired spatial patterns.
Ultracompact phase modulators based on graphene plasmons 27 june 2017 phase modulation due to a local wavelength change. Due to the capabilities to break through the abbes diffraction limit and implement tight field confinement, surface plasmon polaritons spps have triggered a large number of applications at subwavelength scale 2,3,4. Transformation optics aims to identify artificial materials and structures with desired electromagnetic properties by means of pertinent coordinate transformations. In addition, using two graphene layers for the active medium can further increase the optical absorption and modulation depth, giving advantages including smaller footprint and lower power consumptions. Switching terahertz waves with gatecontrolled active. The ones marked may be different from the article in the profile. We report a theoretical study showing that by designing and manipulating spatially inhomogeneous, nonuniform conductivity patterns across a flake of graphene, one can have this. The absorption rates of graphene squarering structures calculated by simulation are 90.
Using this priority and taking the advantage of transformation optics, we realize the concept of electromagnetic black hole by using of a singlelayer. Therefore, relying on the freedom in varying graphene conducitivty by using the methods mentioned above, by tuning the level of chemical potential locally, we can create desired patterns of effective index for spp surface waves. Graphene is in many ways the ultimate thin film, only one. We demonstrate a tunable plasmonic metasurface by considering a graphene sheet subject to a periodically patterned doping level. Controlling spatial patterns of plasmons constitutes a basis for a variety of applications in the fields of plasmonics, metamaterials, and transformation optics 1,2,3. Govorov, plasmoninduced circular dichroism of a chiral molecule in the vicinity of metal nanocrystals. Graphenebased terahertz antennas for areaconstrained applications.
A structure consisting of a graphene sheet sandwiched between two graphene disks is introduced herein to control the reflection, absorption, and. Another area of science that has been under the spotlight for the last few years relates to exploration of graphene, which is formed of carbon atoms densely. Adaptive tetrahedral meshing with a minimum feature resolution of 0. Graphenebased terahertz antennas for areaconstrained.
This could be useful for designing oneatomthick metamaterial and transformation optics devices based on graphene 7. The absorption rates of graphenesquarering structures calculated by simulation are 90. It is known that by varying the chemical potential using gate electric andor magnetic fields, the. The terahertz thz gap lying between the microwave and optical parts of the electromagnetic spectrum has attracted immense attention due to its applications between radiofrequency rfmicrowave and photonic systems. Analysis of infrared spectra with narrow band absorption. Graphene as a tunable anisotropic or isotropic plasmonic. Plasmons in graphene 1,2,3,4 can be tuned by using electrostatic gating or chemical doping 5,6,7, and the ability to confine plasmons in very small regions could have applications in. However, to has not permitted us to confine, manipulate, and control spp waves on.
From optical graphene to topological insulator collaborator. Graphene plasmonic lens for manipulating energy flow. In this paper we propose the biomimetic motheye antireflection structures on graphene sheet based on transformation optics. Both analytical and numerical methods have shown that the average reflection losses of 1%.
For this conductivity for the wavenumber for the tm spp given above, we have. Besides conductivity, we show that the loss of graphene can also be controlled. Recently, transformation optics to based on graphene have received considerable attentions by offering new possibilities to manipulate the propagation of gps 4, in which one graphene sheet can be regarded as a. In the simulations, the radius of the hemisphere a is 100 nm. Transformation optics to offers the capability either to confine the spp propagation on rigid curveduneven surfaces, or to control the flow of spps on planar surfaces. Mar 26, 2012 we have proposed and demonstrated the modulating spp waves by using a singlelayer graphene to realize the concept of black hole, based on the transformation optics. Introduction graphene, a one atom thick layer of carbon atoms arranged in a honeycomb lattice 1, features unique optical 2 and optoelectronic properties 3. Transformation optics is an emerging field of research aiming to conceal an object by bending or distorting electromagnetic waves using spatially varying metamaterials 49, 50. Tunable graphene metasurface reflectarray for cloaking, illusion, and focusing sudipta romen biswas,1 cristian e. Apr 19, 2016 we demonstrate a tunable plasmonic metasurface by considering a graphene sheet subject to a periodically patterned doping level. Because the tunability of the chemical potential of the graphene, we can see that it is feasible to realize the graded refractive index by manipulating the conductivity of graphene. Pdf optical conductivity of graphene in the visible. A longterm goal of electronics has been to make devices smaller, faster, lighter and cheaper.
We investigate a novel implementation of hyperbolic metama. His current research interests include the areas of metamaterials, antennas, invisibility cloaking, transformation optics, and graphene. Yee, numerical solution of initial boundary value problems involving maxwells equations in isotropic. Metamaterials and transformation optics have received considerable attention in the recent years, as they have found an immense role in many areas of optical science and engineering by offering schemes to control electromagnetic fields.
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