The area of plasmonics offers the potential of inducing large local
electromagnetic fields in the vicinity of metallic surfaces and
has been exploited in areas such as Surface Plasmon Resonance (SPR).
The plasmonic properties of nanostructures have recently gained
much attention, particularly for their use in surface enhanced spectroscopy.
|SEM micrograph of fabricated SERS active Plasmonic
Photonic Crystal structure.
By metal-coating the patterned surfaces of the photonic crystals
designed by Mesophotonics, it is possible to introduce plasmonic
dispersion bands. The complex interaction between the underlying
diffraction bands and the surface and localised plasmons allows
much greater control of the confinement of the strong electromagnetic
Once a molecule or analyte is placed in proximity to the electromagnetic
field of the designed broad long range plasmon, it is possible to
form highly controlled and reproducible surface enhanced Raman scattering
|Modelling of a localised plasmon residing in an
air rod of a plasmonic Photonic Crystal.
Mesophotonics has developed rigorous numerical methods to allow
the modelling and design of complex metallic photonic crystals allowing
prediction of the location of the optically enhancing field as illustrated
on the left.
Additionally, the ability to optically characterise the complete
plasmonic dispersion bands of the structures has provided a unique
advantage in developing current and future SERS substrates.
Typical plots of the angular and wavelength dependence of the
dispersion bands of a SERS substrates are shown below.
Experimental angular resolved mapping of reflectivity for a photonic
crystal structure (left) and a metal coated photonic crystal structure
(right). The underlying dispersion bands of the photonic crystal
(red construction lines) as well as the introduced surface plasmon
modes (black lines) are clearly highlighted in each case.