65 research outputs found
Near-field interactions and non-universality in speckle patterns produced by a point source in a disordered medium
A point source in a disordered scattering medium generates a speckle pattern
with non-universal features, giving rise to the so-called C_0 correlation. We
analyze theoretically the relationship between the C_0 correlation and the
statistical fluctuations of the local density of states, based on simple
arguments of energy conservation. This derivation leads to a clear physical
interpretation of the C_0 correlation. Using exact numerical simulations, we
show that C_0 is essentially a correlation resulting from near-field
interactions. These interactions are responsible for the non-universality of
C_0, that confers to this correlation a huge potential for sensing and imaging
at the subwavelength scale in complex media
Radiative and non-radiative local density of states on disordered plasmonic films
We present numerical calculations of the Local Density of Optical States
(LDOS) in the near field of disordered plasmonic films. The calculations are
based on an integral volume method, that takes into account polarization and
retardation effects, and allows us to discriminate radiative and non-radiative
contributions to the LDOS. At short distance, the LDOS is dominated by
non-radiative channels, showing that changes in the spontaneous dynamics of
dipole emitters are driven by non-radiative coupling to plasmon modes. Maps of
radiative and non-radiative LDOS exhibit strong fluctuations, but with
substantially different spatial distributions
Spatial coherence in complex photonic and plasmonic systems
The concept of cross density of states characterizes the intrinsic spatial
coherence of complex photonic or plasmonic systems, independently on the
illumination conditions. Using this tool and the associated intrinsic coherence
length, we demonstrate unambiguously the spatial squeezing of eigenmodes on
disordered fractal metallic films, thus clarifying a basic issue in plasmonics
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