Nano-Optics in Graded Plasmonic Crystals (On-going)

We propose to study the coupled surface plasmon modes in graded plasmonic
crystals which are fabricated by structuring noble-metal (like gold or
silver) nanoparticles in an array with gradually varying spacing, particle
size or particle shape. Electromagnetic (EM) energy transfer can occur due
to the coupled plasmon modes of the individual nanoparticles. However, due
to the presence of inhomogeneity (gradation), there is a possible
localization transition of these plasmon modes. Moreover, the localization
characteristics can differ significantly from that of the usual impurity
localized modes. We aim at sorting out the mechanism of the
localization-delocalization transition of the coupled modes due to the
collective behaviors of the surface plasmon resonance of the individual
particles. We show that by varying the frequency of the incident EM waves,
one can localize or propagate (transmit) the EM energy through the
plasmonic crystals. Thus we can realize the photonic analogue of
electronic junctions for many potential applications in nano-optics.