168 research outputs found
Fundamental Limits for Light Absorption and Scattering Induced by Cooperative Electromagnetic Coupling
Absorption and scattering of electromagnetic waves by dielectric media are of
fundamental importance in many branches of physics. In this Letter we
analytically derived the ultimate upper limits for the absorbed and scattered
powers by any system of optical resonators in mutual interaction. We show that
these bounds depend only on the geometric configuration given an incident
field. We give the conditions to fullfill to reach these limits paving so a way
for a rational design of optimal metamaterials
Proposal for compact solid-state III-V single-plasmon sources
We propose a compact single-plasmon source operating at near-infrared
wavelengths on an integrated III-V semiconductor platform, with a thin ridge
waveguide serving as the plasmon channel. By attaching an ultra-small cavity to
the channel, it is shown that both the plasmon generation efficiency ({\beta})
and the spontaneous-decay rate into the channel can be significantly enhanced.
An analytical model derived with the Lorentz reciprocity theorem captures the
main physics involved in the design of the source and yields results in good
agreement with fully-vectorial simulations of the device. At resonance, it is
predicted that the ultra-small cavity increases the {\beta}-factor by 70% and
boosts the spontaneous decay rate by a factor 20. The proposed design could
pave the way towards integrated and scalable plasmonic quantum networks.
Comparison of the present design with other fully-dielectric competing
approaches is addressed.Comment: 8 pages, 4 figure
A surface-scattering model satisfying energy conservation and reciprocity
In order for surface scattering models to be accurate they must necessarily
satisfy energy conservation and reciprocity principles. Roughness scattering
models based on Kirchoff's approximation or perturbation theory do not satisfy
these criteria in all frequency ranges. Here we present a surface scattering
model based on analysis of scattering from a layer of particles on top of a
substrate in the dipole approximation which satisfies both energy conservation
and reciprocity and is thus accurate in all frequency ranges. The model takes
into account the absorption in the substrate induced by the particles but does
not take into account the near-field interactions between the particles.Comment: 15 pages, 10 figure
RETICOLO software for grating analysis
RETICOLO implements the rigorous coupled wave analysis (RCWA) for 1D
(classical and conical diffraction) and 2D crossed gratings. It operates under
a MATLAB environment and incorporates an efficient and accurate toolbox for
computing Bloch modes and visualizing the electromagnetic field in the grating
region. As a spin-off, the Version V9 launched in 2021 includes a toolbox for
the analysis of stacks of arbitrarily anisotropic multilayered thin-films
Polaritonic modes in a dense cloud of atoms
We analyze resonant light scattering by an atomic cloud in a regime where
near-field interactions between scatterers cannot be neglected. We first use a
microscopic approach and calculate numerically the eigenmodes of the cloud for
many different realizations. It is found that there always exists a small
number of polaritonic modes that are spatially coherent and superradiant. We
show that scattering is always dominated by these modes. We then use a
macroscopic approach by introducing an effective permittivity so that the
atomic cloud is equivalent to a dielectric particle. We show that there is a
one-to-one correspondence between the microscopic polaritonic modes and the
modes of a homogeneous particle with an effective permittivity
Bound states in the continuum in symmetric and asymmetric photonic crystal slabs
We develop a semi-analytical model to describe bound states in the continuum
(BICs) in photonic crystal slabs. We model leaky modes supported by photonic
crystal slabs as a transverse Fabry-Perot resonance composed of a few
propagative Bloch waves bouncing back and forth vertically inside the slab.
This multimode Fabry-Perot model accurately predicts the existence of BICs and
their positions in the parameter space. We show that, regardless of the slab
thickness, BICs cannot exist below a cut-off frequency, which is related to the
existence of the second-order Bloch wave in the photonic crystal. Thanks to the
semi-analyticity of the model, we investigate the dynamics of BICs with the
slab thickness in symmetric and asymmetric photonic crystal slabs. We evidence
that the symmetry-protected BICs that exist in symmetric structures at the
{\Gamma}-point of the dispersion diagram can still exist when the horizontal
mirror symmetry is broken, but only for particular values of the slab
thickness
Solid-state single photon sources: the nanowire antenna
International audienceWe design several single-photon-sources based on the emission of a quantum dot embedded in a semiconductor (GaAs) nanowire. Through various taper designs, we engineer the nanowire ends to realize efficient metallic-dielectric mirrors and to reduce the divergence of the far-field radiation diagram. Using fully-vectorial calculations and a comprehensive Fabry-Perot model, we show that various realistic nanowire geometries may act as nanoantennas (volume of ≈0.05 λ3) that assist funnelling the emitted photons into a single monomode channel. Typically, very high extraction efficiencies above 90% are predicted for a collection optics with a numerical aperture NA=0.85. In addition, since no frequency-selective effect is used in our design, this large efficiency is achieved over a remarkably broad spectral range, 70 nm at λ=950 nm
Non-Local Control of Single Surface Plasmon
Quantum entanglement is a stunning consequence of the superposition
principle. This universal property of quantum systems has been intensively
explored with photons, atoms, ions and electrons. Collective excitations such
as surface plasmons exhibit quantum behaviors. For the first time, we report an
experimental evidence of non-local control of single plasmon interferences
through entanglement of a single plasmon with a single photon. We achieved
photon-plasmon entanglement by converting one photon of an entangled photon
pair into a surface plasmon. The plasmon is tested onto a plasmonic platform in
a Mach-Zehnder interferometer. A projective measurement on the polarization of
the photon allows the non-local control of the interference state of the
plasmon. Entanglement between particles of various natures paves the way to the
design of hybrid systems in quantum information networks.Comment: 6 pages, 3 figure
- …