1,046 research outputs found
Purcell effect in wire metamaterials
We study theoretically the enhancement of spontaneous emission in wire
metamaterials. We analyze the dependence of the Purcell factor dependence on
wire dielectric constant for both electric and magnetic dipole sources, and
find an optimal value of the dielectric constant for maximizing the Purcell
factor for the electric dipole. We obtain analytical expressions for the
Purcell factor and also provide estimates for the Purcell factor in realistic
structures operating in both microwave and optical spectral range.Comment: 15 pages, 7 figure
Green function for hyperbolic media
We revisit the problem of the electromagnetic Green function for homogeneous
hyperbolic media, where longitudinal and transverse components of the
dielectric permittivity tensor have different signs. We analyze the dipole
emission patterns for both dipole orientations with respect to the symmetry
axis and for different signs of dielectric constants, and show that the
emission pattern is highly anisotropic and has a characteristic cross-like
shape: the waves are propagating within a certain cone and are evanescent
outside this cone. We demonstrate the coexistence of the cone-like pattern due
to emission of the extraordinary TM-polarized waves and elliptical pattern due
to emission of ordinary TE-polarized waves. We find a singular complex term in
the Green function, proportional to the function and governing the
photonic density of states and Purcell effect in hyperbolic media.Comment: 10 pages, 7 figure
Scattering Suppression from Arbitrary Objects in Spatially-Dispersive Layered Metamaterials
Concealing objects by making them invisible to an external electromagnetic
probe is coined by the term cloaking. Cloaking devices, having numerous
potential applications, are still face challenges in realization, especially in
the visible spectral range. In particular, inherent losses and extreme
parameters of metamaterials required for the cloak implementation are the
limiting factors. Here, we numerically demonstrate nearly perfect suppression
of scattering from arbitrary shaped objects in spatially dispersive
metamaterial acting as an alignment-free concealing cover. We consider a
realization of a metamaterial as a metal-dielectric multilayer and demonstrate
suppression of scattering from an arbitrary object in forward and backward
directions with perfectly preserved wavefronts and less than 10% absolute
intensity change, despite spatial dispersion effects present in the composite
metamaterial. Beyond the usual scattering suppression applications, the
proposed configuration may serve as a simple realisation of scattering-free
detectors and sensors
Tailoring and enhancing spontaneous two-photon emission processes using resonant plasmonic nanostructures
The rate of spontaneous emission is known to depend on the environment of a
light source, and the enhancement of one-photon emission in a resonant cavity
is known as the Purcell effect. Here we develop a theory of spontaneous
two-photon emission for a general electromagnetic environment including
inhomogeneous dispersive and absorptive media. This theory is used to evaluate
the two-photon Purcell enhancement in the vicinity of metallic nanoparticles
and it is demonstrated that the surface plasmon resonances supported by these
particles can enhance the emission rate by more than two orders of magnitude.
The control over two-photon Purcell enhancement given by tailored
nanostructured environments could provide an emitter with any desired spectral
response and may serve as an ultimate route for designing light sources with
novel properties
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