42 research outputs found
Decomposing the scattered field of two-dimensional metaatoms into multipole contributions
We introduce a technique to decompose the scattered near field of
two-dimensional arbitrary metaatoms into its multipole contributions. To this
end we expand the scattered field upon plane wave illumination into cylindrical
harmonics as known from Mie theory. By relating these cylin- drical harmonics
to the field radiated by Cartesian multipoles, the contribution of the lowest
order electric and magnetic multipoles can be identified. Revealing these
multipoles is essential for the design of metamaterials because they largely
determine the character of light propagation. In par- ticular, having this
information at hand it is straightforward to distinguish between effects that
result either from the arrangement of the metaatoms or from their particular
design
Analytical Model for Metamaterials with Quantum Ingredients
We present an analytical model for describing complex dynamics of a hybrid
system consisting of interacting classical and quantum resonant structures.
Classical structures in our model correspond to plasmonic nano-resonators of
different geometries, as well as other types of nano- and micro-structures
optical response of which can be described without invoking quantum-mechanical
treatment. Quantum structures are represented by atoms or molecules, or their
aggregates (for example, quantum dots and carbon nanotubes), which can be
accurately modelled only with the use of quantum approach. Our model is based
on the set of equations that combines well-established density matrix formalism
appropriate for quantum systems, coupled with harmonic-oscillator equations
ideal for modelling sub-wavelength plasmonic and optical resonators. This model
can also be straightforwardly adopted for describing electromagnetic dynamics
of various hybrid systems outside the photonics realm, such as
Josephson-junction metamaterials, or SQUID elements coupled with an RF strip
resonator.Comment: 9 pages, no figure
Multipole nonlinearity of metamaterials
We report on the linear and nonlinear optical response of metamaterials
evoked by first and second order multipoles. The analytical ground on which our
approach bases permits for new insights into the functionality of
metamaterials. For the sake of clarity we focus here on a key geometry, namely
the split-ring resonator, although the introduced formalism can be applied to
arbitrary structures. We derive the equations that describe linear and
nonlinear light propagation where special emphasis is put on second harmonic
generation. This contribution basically aims at stretching versatile and
existing concepts to describe light propagation in nonlinear media towards the
realm of metamaterials.Comment: 7 pages, 3 figure
Contribution of the magnetic resonance to the third harmonic generation from a fishnet metamaterial
We investigate experimentally and theoretically the third harmonic generated
by a double-layer fishnet metamaterial. To unambiguously disclose most notably
the influence of the magnetic resonance, the generated third harmonic was
measured as a function of the angle of incidence. It is shown experimentally
and numerically that when the magnetic resonance is excited by pump beam, the
angular dependence of the third harmonic signal has a local maximum at an
incidence angle of {\theta} \simeq 20{\deg}. This maximum is shown to be a
fingerprint of the antisymmetric distribution of currents in the gold layers.
An analytical model based on the nonlinear dynamics of the electrons inside the
gold shows excellent agreement with experimental and numerical results. This
clearly indicates the difference in the third harmonic angular pattern at
electric and magnetic resonances of the metamaterial.Comment: 7 pages, 5 figure