  Quasi-crystals are intriguing as they exhibit rotational symmetry and long
range ordering but lack translational symmetry. 2-dimensional metal-dielectric
patterns are interesting to make use of surface plasmon polariton (SPP)
mediated local field enhancement and for near dispersionless SPP modes. In
plasmonic crystals, the orientation and periodicity of the pattern dictate the
polarization response and the discrete plasmon resonances while the interfaces
define the plasmon dispersion. However, unique properties of plasmonic
quasicrystals lead to polarization independence, designable k-space and
broadband transmission enhancement due to SPP mediation. These are useful in
many applications like energy harvesting, nonlinear optics and quantum
plasmonics. We demonstrate design and fabrication of large area quasicrystal
air hole patterns of pi/5 symmetry in metal film in which broadband, launch
angle and polarization independent transmission enhancement as well as
broadband second harmonic generation are observed. Designable transmission
response, other symmetries and tilings are possible.
