Facile fabrication of nanoapertures with tunable plasmonic resonances

In the present work, we fabricate nano-apertures (NAs) in gold thin films using shadow sphere lithography exhibiting tunable plasmonic resonances. The control over the plasmon resonances is achieved by varying the conditions used for the shadow sphere lithography process. Two different sizes of masks have been used to realize apertures of different diameters. Furthermore, the effect of thickness on the optical response have been investigated. From single aperture scattering measurements, it is seen that on increasing the mask size, the resonance wavelength shifted towards higher wavelengths. In contrary, increasing the thickness of the gold thin films results in a blue shift of the resonance.