In this work, we investigated how the blinking statistics and the photon antibunching behavior of single CdSe/CdS
core/shell quantum dots(QDs) get modified in the presence of gold nanoparticles(Au NPs) overcoated with a silica shell
of varying thickness.(Au@SiO2). The Au@SiO2 NPs have distinct plasmon resonance peaks which overlap with the
absorption and emission of QDs, thereby effectively increasing the mutual plasmon-exciton interactions between them.
From the second-order photoluminescence intensity cross-correlation measurements, we observed that in the regime of
low excitation power, the relative ratio of the biexciton/exciton (BX/X) quantum yield (QY) and lifetimes of the single
QDs in presence of the plasmonic substrates get significantly modified as compared to the QDs on glass. An
electrodynamics model was developed to further quantify the effect of plasmons on the emission intensity, QY and
lifetimes of X and BX of single QDs. The theoretical studies also indicated that the relative position of the QDs and
orientation of the electric field are the critical factors regulating the emission properties of Xs and BXs.
The effect of surrounding medium on the optical properties of a two layer silver film are
investigated using an analytical model. We varied the media before the first layer, between
the two layers, and after the second layer. We find that the optical properties of the film is
dominantly determined by the medium between the two layers. The resonance wavelength
red shifts when the medium between the two layers is changed from vacuum to water and
then glass. The media before the first layer and after the second layer have little effect on the
spectra of the film when the thicknesses of the layers are larger than 40 nm.
We investigate the reflectivity of glass thin films with different nanostructures using electromagnetic theory.
The Discrete Dipole Approximation (DDA) method is used in the calculations. The thickness of the film is
varied from 50 to 200 nm. Films composed of semi-ellipsoid, cylinder, and prism particle arrays are
examined in order to understand the structure dependence of the thin film reflectivity at nanoscale level.
When the film thickness is 50 nm, films with effective dielectric constant gradient exhibit lower reflectivity
than those with the uniform dielectric constant. At short wavelengths, the thin film nanostructure has a
significant influence to its reflectivity. For longer ones, especially when the wavelength is much larger than
the film thickness, the effect of the nanostructure becomes less important and the volume of the film evolves
to be an important factor. We also explore the reflectivity of glass films including a 100 nm thick solid
substrate layer and nanostructures of different heights. For a film with semi-ellipsoid arrays of the same
thickness, its reflectivity drops with the increase of the semi-ellipsoid diameter. The simulation results can be
of help in the design of thin film solar cell coating for the enhancement of solar energy conversion efficiency.
The extinction spectra of hole arrays in a silver film are investigated with discrete dipole approximation method. The
influences of distances between holes to the extinction spectra are explored; the effects of shapes and sizes of holes on
the extinction spectra are also probed. For holes of the same areas, simulations show that the holes with square and
rectangular shapes exhibit more efficient couplings compared with the circular ones. The increased aspect ratios
(length/width) of rectangular holes perpendicular to the polarization direction strengthen their couplings. The
influences of hole distances to the extinction spectra are examined. In the simulations, the lattice areas of hole arrays
are first kept to be a constant (400×400 nm<sup>2</sup>), and then allowed to be changed with one fixed edge length of the
rectangular lattice arrays. The calculations indicate that the extinction resonance wavelengths are more sensitive to the
hole spacings along the polarization direction. The distance variations perpendicular to the polarization direction only
alter the strengths of the coupling between holes and show little impact to the resonance wavelengths.