A Positive Future for Double-Negative Metamaterials

Metamaterials (MTMs), which are formed by embedding inclusions and material components in host media to achieve composite media that may be engineered to have qualitatively new physically realizable response functions that do not occur or may not be easily available in nature, have raised a great deal of interest in recent years. In this paper, we highlight a large variety of the physical effects associated with double- and single-negative MTMs and some of their very interesting potential applications. The potential ability to engineer materials with desired electric and magnetic properties to achieve unusual physical effects offers a great deal of excitement and promise to the scientific and engineering community. While some of the applications we will discuss have already come to fruition, there are many more yet to be explored

The Design and Simulated Performance of a Coated Nano-Particle Laser

The optical properties of a concentric nanometer-sized spherical shell comprised of an (active) 3-level gain medium core and a surrounding plasmonic metal shell are investigated. Current research in optical metamaterials has demonstrated that including lossless plasmonic materials to achieve a negative permittivity in a nano-sized coated spherical particle can lead to novel optical properties such as resonant scattering as well as transparency or invisibility. However, in practice, plasmonic materials have high losses at optical frequencies. It is observed that with the introduction of active materials, the intrinsic absorption in the plasmonic shell can be overcome and new optical properties can be observed in the scattering and absorption cross-sections of these coated nano-sized spherical shell particles. In addition, a "super" resonance is observed with a magnitude that is greater than that for a tuned, resonant passive nano-sized coated spherical shell. This observation suggests the possibility of realizing a highly sub-wavelength laser with dimensions more than an order of magnitude below the traditional half-wavelength cavity length criteria. The operating characteristics of this coated nano-particle (CNP) laser are obtained numerically for a variety of configurations.Comment: 35 pages. Revision submitted to Optics Express, Feb 15, 2007. This replacement is intended to clarify the work presented in the previous version of this paper. In particular, the definitions and parameters associated with the permittivity that was used to include the three level gain model used in the simulation results presented. The authors also made changes to some of the wording used in the text for better clarity. The results presented in this version are identical to those of the previous versio

Excitation of guided waves in layered structures with negative refraction

We study the electromagnetic beam reflection from layered structures that include the so-called double-negative materials, also called left-handed metamaterials. We predict that such structures can demonstrate a giant lateral Goos-Hanchen shift of the scattered beam accompanied by splitting of the reflected and transmitted beams due to the resonant excitation of surface waves at the interfaces between the conventional and double-negative materials as well as due to excitation of leaky modes in the layered structures. The beam shift can be either positive or negative, depending on the type of the guided waves excited by the incoming beam. We also perform finite-difference time-domain simulations and confirm the major effects predicted analytically.Comment: 13 pqages, 10 figures. Also available at http://www.opticsexpress.org/abstract.cfm?URI=OPEX-13-2-48

Finite-difference time-domain analysis of the tunneling and growing exponential in a pair of ε-negative and µ-negative slabs

Pairing together planar material slabs with opposite signs for the real parts of their constitutive parameters has been shown to lead in the steady-state regime to interesting and unconventional properties that are not otherwise observable for single slabs, such as resonance, anomalous tunneling, transparency, and subwavelength imaging through the reconstruction of evanescent waves [A. Alù and N. Engheta, IEEE Trans. Antennas Prop. 51, 2558 (2003)]. The mechanics of the phenomenon, however, and in particular how the steady-state resonant response is reached, has not been explored. Here we analyze how a transient sinusoidal signal that starts at t = 0 interacts with such a complementary pair of finite size using a finite-difference time-domain (FDTD) technique. Multiple reflections and transmissions at each interface are shown to build up to the eventual steady-state response of the pair, and during this process one can observe how the “growing exponential” phenomenon may actually occur inside this bilayer. As with any resonant phenomena, the time response of this effect depends on the Q of the system, which is related to the geometrical and electrical parameters of the bilayer. Transparency to finite beams and reconstruction of the subwavelength details of an image are shown in the transient and steady-state response of the setup through one-dimensional and two-dimensional FDTD simulations

Least Upper Bounds of the Powers Extracted and Scattered by Bi-anisotropic Particles

The least upper bounds of the powers extracted and scattered by bi-anisotropic particles are investigated analytically. A rigorous derivation for particles having invertible polarizability tensors is presented, and the particles with singular polarizability tensors that have been reported in the literature are treated explicitly. The analysis concludes that previous upper bounds presented for isotropic particles can be extrapolated to bi-anisotropic particles. In particular, it is shown that neither nonreciprocal nor magnetoelectric coupling phenomena can further increase those upper bounds on the extracted and scattered powers. The outcomes are illustrated further with approximate circuit model examples of two dipole antennas connected via a generic lossless network.Comment: 9 pages, 1 figure

FDTD analysis of the tunneling and growing exponential in a pair of epsilon-negative and mu-negative slabs

Pairing together material slabs with opposite signs for the real parts of their constitutive parameters has been shown to lead to interesting and unconventional properties that are not otherwise observable for single slabs. One such case was demonstrated analytically for the conjugate (i.e., complementary) pairing of infinite planar slabs of epsilon-negative (ENG) and mu-negative (MNG) media [A. Alu, and N. Engheta, IEEE Trans. Antennas Prop., 51, 2558 (2003)]. There it was shown that when these two slabs are juxtaposed and excited by an incident plane wave, resonance, complete tunneling, total transparency and reconstruction of evanescent waves may occur in the steady-state regime under a monochromatic excitation, even though each of the two slabs by itself is essentially opaque to the incoming radiation. This may lead to virtual imagers with sub-wavelength resolution and other anomalous phenomena overcoming the physical limit of diffraction. Here we explore how a transient sinusoidal signal that starts at t = 0 interacts with such an ENG-MNG pair of finite size using an FDTD technique. Multiple reflections and transmissions at each interface are shown to build up to the eventual steady state response of the pair, and during this process one can observe how the growing exponential phenomenon may actually occur inside this bilayer.Comment: 14 pages, 9 figures, submitted to Phys Rev