Plasmon resonance wavelength controlled by SiO2 layer thickness on a silver surface and nanoantenna effect at a center of Bull's eye pattern

Abstract

The fluorescence enhancement is induced by Grating-coupled surface plasmon resonance (GC-SPR) of a plasmonic chip in which a wavelength-sized periodic structure is coated with a thin metal film. In the fluorescence microscopic images of nanoparticles adsorbed on the plasmonic chip observed with transmitted light, the bright spot based on the nanoantenna effect was observed at the center of a Bull's eye pattern composed of concentric circles in a plasmonic chip. In this study, resonance wavelength was controlled by SiO2 film thickness deposited on a thin Ag film and the excitation and emission enhancement was individually evaluated by an upright-inverted microscope to clarify the cause of the nanoantenna effect. As the observation result, nanoantenna effect was larger in SiO2 80 nm than SiO2 20 nm.