Publications (5)0 Total impact
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ABSTRACT: We propose a two dimensional (2D) photonic crystal (PhC) structure that supports super-collimation over a large frequency range (over 4 times that of a traditional square lattice of holes). We theoretically and numerically investigate the collimation mechanism in our 2D structure, in comparison to that of two other frequently used related PhC structures. We also point out the potential importance of our proposed structure in the design of super-collimation-based devices for both monochromatic and polychromatic light.
Rafif E. Hamam.
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ABSTRACT: Inspired by a quantum interference phenomenon known in the atomic physics community as electromagnetically induced transparency (EIT), we propose an efficient weakly radiative wireless energy transfer scheme between two identical classical resonant objects, strongly coupled to an intermediate classical resonant object of substantially different properties, but with the same resonance frequency. The transfer mechanism essentially makes use of the adiabatic evolution of an instantaneous (so called “dark”) eigenstate of the coupled 3-object system. Our analysis is based on temporal coupled mode theory (CMT), and is general enough to be valid for various possible sorts of coupling, including the resonant inductive coupling on which witricity-type wireless energy transfer is based. We show that in certain parameter regimes of interest, this scheme can be more efficient, and/or less radiative than other, more conventional approaches. A concrete example of wireless energy transfer between capacitively-loaded metallic loops is illustrated at the beginning, as a motivation for the more general case. We also explore the performance of the currently proposed EIT-like scheme, in terms of improving efficiency and reducing radiation, as the relevant parameters of the system are varied. U.S. Department of Energy DARPA Army Research Office National Science Foundation
Rafif E. Hamam.
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ABSTRACT: We present a method to compute Casimir forces in arbitrary geometries and for arbitrary materials based on the finite-difference time-domain (FDTD) scheme. The method involves the time evolution of electric and magnetic fields in response to a set of current sources, in a modified medium with frequency-independent conductivity. The advantage of this approach is that it allows one to exploit existing FDTD software, without modification, to compute Casimir forces. In this paper, we focus on the derivation, implementation choices, and essential properties of the time-domain algorithm, both considered analytically and illustrated in the simplest parallel-plate geometry.
APS.
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ABSTRACT: A material platform of multilayered surface-plasmon-dielectric-polariton systems is introduced, along with a new physical mechanism enabling simultaneous cancellation of group-velocity and attenuation dispersion to extremely high orders for subwavelength light of any small positive, negative, or zero group velocity. These dispersion-free systems could have significant impact on the development of nanophotonics, e.g., in the design of efficient and very compact delay lines and active devices. The same dispersion-manipulation mechanism can be employed to tailor at will exotic slow-light dispersion relations. Army Research Office, ISN National Science Foundation MRSEC Program
APS.
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ABSTRACT: A new physical mechanism enabling simultaneous cancellation of group-velocity and attenuation dispersion to extremely high orders for subwavelength light of any small positive, negative or zero value of the group velocity is introduced. It exploits the unique dispersive properties of the surface polaritons supported by a novel proposed material platform of multilayered Surface-PlasmonoDielectric-Polaritonic (SPDP) systems. These single-polarization broadband-slow- or stopped-light systems are thus essentially free from all kinds of dispersion and could therefore have great impact on the technology of integrated nanophotonics, for example in the design of efficient and very compact delay lines and active devices. The same dispersion-manipulation mechanism can be employed to invent a large variety of exotic slow-light dispersion relations. United States. Army Research Office. Institute for Soldier Nanotechnologies (Contract No. W911NF-07-D-0004) MRSEC Program of the National Science Foundation (Grant No. DMR 02-13282)
SPIE.
