AbstractIn this work we have studied transmission and scattering of light through hexagonally packed circular subwavelength holes in optically thin and thick metallic film. The gold nanohole arrays are fabricated on glass substrate by combining nanosphere lithography with dry-etching technique. We observed that the transmission resonances of the thin films are significantly different than that of the thick films due to the coupling of plasmons at metal/air and metal/glass interfaces. We also investigated the effect of the diameter and the periodicity on the transmission resonance by controlling the dry-etching time and the bead size used in lithography, respectively. Finally, we have looked at the spectral response of the fabricated structures in media with different refractive indexes for bio-sensing application.
Enhanced optical transmission through sub-wavelength centered-polygonal hole arrays in silver thin film on silica substrate