1,991 research outputs found
Design, Concepts and Applications of Electromagnetic Metasurfaces
The paper overviews our recent work on the synthesis of metasurfaces and
related concepts and applications. The synthesis is based on generalized sheet
transition conditions (GSTCs) with a bianisotropic surface susceptibility
tensor model of the metasurface structure. We first place metasurfaces in a
proper historical context and describe the GSTC technique with some fundamental
susceptibility tensor considerations. Upon this basis, we next provide an
in-depth development of our susceptibility-GSTC synthesis technique. Finally,
we present five recent metasurface concepts and applications, which cover the
topics of birefringent transformations, bianisotropic refraction, light
emission enhancement, remote spatial processing and nonlinear second-harmonic
generation
A geometrical setting for the classification of multilayers
We elaborate on the consequences of the factorization of the transfer matrix
of any lossless multilayer in terms of three basic matrices of simple
interpretation. By considering the bilinear transformation that this transfer
matrix induces in the complex plane, we introduce the concept of multilayer
transfer function and study its properties in the unit disk. In this
geometrical setting, our factorization translates into three actions that can
be viewed as the basic pieces for understanding the multilayer behavior.
Additionally, we introduce a simple trace criterion that allows us to classify
multilayers in three types with properties closely related to one (and only
one) of these three basic matrices. We apply this approach to analyze some
practical examples that are representative of these types of matrices.Comment: 8 pages, 5 figures. To be published in J. Opt. Soc. Am.
General Metasurface Synthesis Based on Susceptibility Tensors
A general method, based on susceptibility tensors, is proposed for the
synthesis of metasurfaces transforming arbitrary incident waves into arbitrary
reflected and transmitted waves. The proposed method exhibits two advantages:
1)it is inherently vectorial, and therefore better suited for full vectorial
(beyond paraxial) electromagnetic problems, 2) it provides closed-form
solutions, and is therefore extremely fast. Incidentally, the method reveals
that a metasurface is fundamentally capable to transform up to four independent
wave triplets (incident, reflected and refracted waves). In addition, the paper
provides the closed-form expressions relating the synthesized susceptibilities
and the scattering parameters simulated within periodic boundary conditions,
which allows one to design the scattering particles realizing the desired
susceptibilities. The versatility of the method is illustrated by examples of
metasurfaces achieving the following transformations: generalized refraction,
reciprocal and non-reciprocal polarization rotation, Bessel vortex beam
generation, and orbital angular momentum multiplexing
A Radial-Dependent Dispersive Finite-Difference Time-Domain Method for the Evaluation of Electromagnetic Cloaks
A radial-dependent dispersive finite-difference time-domain (FDTD) method is
proposed to simulate electromagnetic cloaking devices. The Drude dispersion
model is applied to model the electromagnetic characteristics of the cloaking
medium. Both lossless and lossy cloaking materials are examined and their
operating bandwidth is also investigated. It is demonstrated that the perfect
"invisibility" from electromagnetic cloaks is only available for lossless
metamaterials and within an extremely narrow frequency band.Comment: 18 pages, 10 figure
Formation of Non-reciprocal Bands in Magnetized Diatomic Plasmonic Chains
We show that non-reciprocal bands can be formed in a magnetized periodic
chain of spherical plasmonic particles with two particles per unit cell.
Simplified form of symmetry operators in dipole approximations are used to
demonstrate explicitly the relation between spectral non-reciprocity and broken
spatial-temporal symmetries. Due to hybridization among plasmon modes and free
photon modes, strong spectral non-reciprocity appears in region slightly below
the lightline, where highly directed guiding of energy can be supported. The
results may provide a clear guidance on the design of one-way waveguides
Fundamental Properties and Classification of Polarization Converting Bianisotropic Metasurfaces
We provide a detailed discussion on the electromagnetic modeling and
classification of polarization converting bianisotropic metasurfaces. To do so,
we first present a general approach to compute the scattering response of such
metasurfaces, which relies on a generalized sheet transition conditions based
susceptibility model. Then, we review how the fundamental properties of
reciprocity, energy conservation, rotation invariance and matching may be
expressed in terms of metasurface susceptibilities and scattering parameters,
and show how these properties may affect and limit the polarization effects of
metasurfaces. Finally, we connect together the metasurface susceptibility model
to the structural symmetries of scattering particles and their associated
polarization effects. This work thus provides a detailed understanding of the
polarization conversion properties of metasurfaces and may prove to be of
particular interest for their practical implementation
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