Biomedical Engineering Reference
In-Depth Information
QD-CNP case, the QD layer is within the cavity formed by the silica
core and the metal shell. Thus, the coupling of the large fields in the
core to the SPPs created in the Ag shell at the Ag-QD (i.e., an
ε<
0,
ε
>
0) interface provides a much larger feedback mechanism through
the QD gain layer. This feedback is much smaller in the IO-CNP case
because it occurs between the outside vacuum region and the metal
shell. These interpretations are supported by earlier three-layer
observationsthatincludedanexteriormetalcoatingtothebasicIO-
CNP configuration that substantially improved its performance.
14.3 Coated Nanoparticles Excited by Electric Hertizan
Dipoles
The present section investigates the fundamental electromagnetic
properties of spherical active CNPs with the aim of clarifying
their suitability and potential as elements for nano-antennas, and
as elements for the jamming applications of quantum emitters.
The investigated CNPs again consist of a SiO
2
spherical nano-core
coveredwithaplasmonicsphericalconcentricnano-shell.Attention
is devoted to the near and far-field behavior of these particles in
the presence of a single or multiple EHDs. In particular, the impacts
of the plasmonic material, the dipole orientation, and locations on
the resonant and transparent properties of the suggested CNPs
have all been investigated thoroughly. In the analysis, a constant
frequency canonical gain model has been used to account for the
gain introduced in the dielectric part of the CNPs, whereas the size
and frequency-dependent models for silver, gold, and copper have
been used for the nano-shell layers of the CNPs.
14.3.1
Problem Formulation
TheCNPconsistsofanano-core(ofradius
r
1
)coveredconcentrically
with a nano-shell (of radius
r
2
), see Fig. 14.8. The nano-core
and nano-shell consist of simple materials with permittivities,
permeabilities, and wave numbers, respectively, denoted by
ε
1
,
μ
1
,
and
k
1
, (for the nano-core) and
μ
2
,and
k
2
(for the nano-shell).
The permittivity and permeability of the ambient free space are
ε
2
,
ε
0
