Annular holes and their arrays for light extraction from high refractive index substrates.

Summary form only given. Transmission through annular aperture arrays has been studied in detail on glass and high refractive index GaP substrate. The optimisation of the geometry of annular apertures and the nature of the transmission enhancement will be discussed. Periodically nanostructured metal films, the so-called plasmonic crystals, are promising structures for many applications ranging from color filtering and multiplexing, light extraction to negative refraction designs. The transmission of light through a plasmonic crystal depends both on the period of the structure and the scattering cross section of the lattice basis. Annular holes offer a very interesting class of geometries for manipulation of optical transmission through metal films. In this work, we report on the studies of the optical transmission of annular hole arrays in metallic layers supporting surface plasmon polaritons. The structures were fabricated on both a glass and a high refractive index substrate GaP. In order to understand the difference between simple circular holes and annular holes, the transmission of circular holes and annular holes with different inner diameters have been investigated and compared to the numerical modelling. Optical transmission spectra and dispersion of the eigenmodes of the structures have been measured. The experimental results and numerical modelling show that the transmission of the annular holes arrays increases as the inner radius of the annular hole increases, a counterintuitive behaviour with more light transmitted through smaller opening area. The observed effect is of importance to understand the effect of high refractive index substrates on the plasmonic properties of annular holes, which may lead to a better light extraction in semiconductor structures where the material involved have high refractive index.