The optical response and plasmon coupling between graphene sheets for graphene/polymer multilayer heterostructures with controlled separation were systematically investigated. Anomalous transmission of light was experimentally observed in mid-infrared range. The position of the broad passband in the transmission spectra was observed to red-shift with the increase of the number of layers.
By Scanning Near-field Optical Microscopy (SNOM), we study the propagation of surface waves created by
nanostructures on a thin gold film. The nanostructures are slits and ridges fabricated by electron or ion beam lithography
techniques. We will first show that the light scattered by a slit made in a gold film illuminated in transmission is
composed of two components: a diffracted field and a surface plasmon polariton that propagates on the gold surface over
several tens of nanometers. When two slits are illuminated, the created waves encounter and form an interference pattern
which involves both the surface plasmon polariton and the diffracted waves. The situation is more complicated when the
nanostructures are illuminated in a reflection mode at oblique incidence. In that case, the created waves are
superimposed to the incident and reflected fields. Despite a larger number of waves, the analysis of the interference
pattern provides several informations on the nature of the scattered waves and their generation rate. In this article, we
provide a qualitative analysis of the waves created by slits, and by linear and curved ridges located on a gold surface.
Electromagnetic(EM) energy can propagate along optical waveguides made by using the dependence of surface plasmon polaritons(SPPs) on nanometer gap width between two parallel metallic plates. Finite-difference timedomain (FDTD) was employed to calculate the propagation constant of this nanoscale metallic waveguide. The agreement between the calculated values and results predicted by the theory of metallic waveguide is quite satisfactory. We then demonstrate a branched structure with right-angle bends and structures that can be used as nanoscale interferometers by using the ideal of nanoscale metallic waveguides. EM energy transfer was simulated in these structures by using FDTD method. The results show that bend and insertion losses both remain at an acceptable level. We also simulated EM energy transfer in nanoscale metallic waveguide arrays. It is found that the energy spreads into two main lobes as the light propagates along the waveguides. The separation angle of the two lobes is determined by the period of the array.