Transformation Optics Using Graphene: One-Atom-Thick Optical Devices Based on Graphene

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. 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 packed into a honey-comb lattice. This material exhibits unconventional electronic and optical properties, intriguing many research groups across the world including us. But our interest is mostly in studying interaction of electromagnetic waves with graphene and applications that might follow. Our group as well as few others pioneered investigating prospect of graphene for plasmonic devices and in particular plasmonic metamaterial structures and transformation optical devices. In this thesis, relying on theoretical models and numerical simulations, we show that by designing and manipulating spatially inhomogeneous, nonuniform conductivity patterns across a flake of graphene, one can have this material as a one-atom-thick platform for infrared metamaterials and transformation optical devices. Varying the graphene chemical potential by using static electric field allows for tuning the graphene conductivity in the terahertz and infrared frequencies. Such design flexibility can be exploited to create patches with differing conductivities within a single flake of graphene. Numerous photonic functions and metamaterial concepts are expected to follow from such platform. This work presents several numerical examples demonstrating these functions. Our findings show that it is possible to design one-atom-thick variant of several optical elements analogous to those in classic optics. Here we theoretically study one-atom-thick metamaterials, one-atom-thick waveguide elements, cavities, mirrors, lenses, Fourier optics and finally a few case studies illustrating transformation optics on a single sheet of graphene in mid-infrared wavelengths

Fourier Optics on Graphene

Using numerical simulations, here, we demonstrate that a single sheet of graphene with properly designed inhomogeneous, nonuniform conductivity distributions can act as a convex lens for focusing and collimating the transverse-magnetic (TM) surface plasmon polariton (SPP) surface waves propagating along the graphene. Consequently, we show that the graphene can act as a platform for obtaining spatial Fourier transform of infrared (IR) SPP signals. This may lead to rebirth of the field of Fourier optics on a 1-atom-thick structure

Mathematical Analysis and Design of Carbon Nanotubes based Nantennas

Recent advances in the fabrication and characterization of nanomaterials have led to intelligible applications of such nanomaterials in next generation flexible electronics and highly efficient photovoltaic devices. Nano devices are moving on a path toward smaller designs. This idea helps scientists to extend the efficiency of nano devices such as antennas, sensors and nano robots. On the other hand, the excellent electron transport property of Graphene makes it an attractive choice for next generation electronics and applications in nanotechnology. In this paper we present a mathematically analyze of Carbon Nanotubes (CNT) based Nano antennas (Nantennas) and further we present some applications regarding to a novel design in scale of nano meter

Nonlinear Control of Tunneling Through an Epsilon-Near-Zero Channel

The epsilon-near-zero (ENZ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch. Here we experimentally demonstrate nonlinear control of the ENZ tunneling by an external field, as well as self-modulation of the transmission resonance due to the incident wave. Using a waveguide section near cut-off frequency as the ENZ system, we introduce a diode with tunable and nonlinear capacitance to demonstrate both of these effects. Our results confirm earlier theoretical ideas on using an ENZ channel for dielectric sensing, and their potential applications for tunable slow-light structures

Nonlinear Control of Tunneling Through an Epsilon-Near-Zero Channel

The epsilon-near-zero (ENZ) tunneling phenomenon allows full transmission of waves through a narrow channel even in the presence of a strong geometric mismatch. Here we experimentally demonstrate nonlinear control of the ENZ tunneling by an external field, as well as self-modulation of the transmission resonance due to the incident wave. Using a waveguide section near cut-off frequency as the ENZ system, we introduce a diode with tunable and nonlinear capacitance to demonstrate both these effects. Our results confirm earlier theoretical ideas on using an ENZ channel for dielectric sensing and their potential applications for tunable slow-light structures

Fabrication and Mathematical Modeling of SWCNT Scaffold DNA Spiral Nantenna

DNA origami based spiral structure is synthesized to realize a nanoscale spiral antenna for biomedical applications. Single strand DNA (ssDNA) origami structures utilize self-assembly techniques and short ssDNA staples to develop the desired spiral structures. This poster will discuss the methods and protocol to develop DNA origami structure. We further present several approaches to make DNA conductive. We also present a mathematical model to calculate the conductivity of nanoscale antenna

Electric Levitation Using ε-Near-Zero Metamaterials

[EN] The ability to manufacture metamaterials with exotic electromagnetic properties has potential for surprising new applications. Here we report how a specific type of metamaterial-one whose permittivity is near zero-exerts a repulsive force on an electric dipole source, resulting in levitation of the dipole. The phenomenon relies on the expulsion of the time-varying electric field from the metamaterial interior, resembling the perfect diamagnetic expulsion of magnetostatic fields. Leveraging this concept, we study some realistic requirements for the levitation or repulsion of a polarized particle radiating at any frequency, from microwave to optics.This work is supported in part by the US Office of Naval Research (ONR) Multidisciplinary University Research Initiative (MURI) Grant No. N00014-10-1-0942. F. J. R.-F. acknowledges financial support from Grant FPI of GV and the Spanish MICINN under Contracts No. CONSOLIDER EMET CSD2008-00066 and No. TEC2011-28664-C02-02.Rodríguez Fortuño, FJ.; Vakil, A.; Engheta, N. (2014). Electric Levitation Using ε-Near-Zero Metamaterials. Physical Review Letters. 112(3):33902-1-33902-5. https://doi.org/10.1103/PhysRevLett.112.033902S33902-133902-5112