  When placed near a thin metallic film, excitons in a quantum dot (QD) decay
into surface plasmon polaritons (SPPs), guided modes of light confined at the
interface of the metal/dielectric. It was reported that the interaction of SPPs
with excitons in a QD may give rise to a modification in the photoluminescence
(PL) spectra of the exciton energy levels, however the mechanism that explains
this modification remains unclear. We propose a new methodology to excite many
energy levels in an exciton by placing the QDs near a metallic array of slits
fabricated onto a thin metallic gold (Au) film. By changing the position under
the array where the QDs are excited we can resolve between the many energy
levels. The unique features of the PL spectra obtained are the result of the
strong electromagnetic field (EMF), the increase in the local density of states
(LDOS) and the mesoscopic effects attributed to the gradient of the SPP field
near the QDs.
