In this work, we report investigations on plasmonic nano-disks using cathodoluminescence (CL) imaging and spectroscopy. 50 nm thick gold disks fabricated using electron beam lithography were studied and several modes were identified. Detailed analysis of the modes using monochromatic imaging and CL spectra showed strong size dependence. Our investigations on these plasmonic nano-disks allow understanding of light-matter interaction at nanoscale, with several potential applications including next generation plasmonic nano-lasers.

The localized surface plasmon resonance (LSPR) is a collective oscillation of conduction electrons confined in metal nanostructures and is largely responsible for surface enhanced spectroscopies. Surface enhanced Raman scattering (SERS) is the best known and most widely applied example of such a surface enhanced spectroscopy. Although closely related and complementary to SERS, surface enhanced infrared absorption (SEIRA) spectroscopy requires more careful engineering of the LSPR of metal nanostructures so that the resonance is within the mid-infrared region. In this study, we demonstrate the use of gold nanorods (Au NR) as a suitable substrate capable of sustaining strong SEIRA spectroscopy. Adsorbate saturated Au NR typically exhibit Fano-type resonances in their SEIRA spectra obtained using reflectance FTIR. Such line asymmetry occurs due to the coupling of the relatively sharp molecular vibrations to the broad continuum of the LSPR resonance of the aggregated Au NR.

Two-dimensional arrays of silver nanocylinders fabricated by electron-beam lithography are used to demonstrate plasmon-enhanced near-green light emission from nitride semiconductor quantum wells. Large enhancements in peak photoluminescence intensity (up to a factor of over 3) are obtained, accompanied by a substantial reduction in recombination lifetime indicative of increased internal quantum efficiency. The measured enhancement factors exhibit a strong dependence on the nanoparticle dimensions, underscoring the importance of geometrical tuning for this application.

Plasmonic nanoresonators can localize light beyond diffraction limit and can provide large field enhancements and thus can be used in sensing and spectroscopy applications. Here, we numerically show that efficient excitation of plasmonic resonances of nanoparticles is possible when they are integrated with Silicon Nitride waveguides in an integrated hybrid photonic-plasmonic platform.

Equilibrium geometries and cohesion energies of Ag0.94Cd0.06, Ag0.94In0.06, Au0.94Cd0.06, and Au0.94In0.06 solid alloys have been studied from the first principles within the Density Functional Theory using ab initio pseudopotentials. Equilibrium geometries are obtained by total energy minimization method using the Local Density Approximation and Generalized Gradient Approximation methods. Optical functions are calculated within the independent particles picture. We report essentially different behavior of Cd and In impurity atoms in Au- and Ag-based alloys: the aggregated (or quasi aggregated) phases in In-containing alloys are expected in contrast to the alloys with Cd atom where homogeneous impurity distribution over the bulk should dominate. Study of optical spectra in Ag0.94Cd0.06 and Au0.94Cd0.06 alloys indicate that optical losses in visible and near ultraviolet spectral range remarkably increase at bigger Cd concentrations. In ultraviolet spectral region redistribution of optical oscillator strengths results in both increase and decrease of optical losses in selected spectral regions.