Effects of dielectric substrate properties for optical phenomena in a nanoscale ridge aperture

In this paper, we show that the increase in power throughput is dependent on the thickness and the relative permittivity of the dielectric substrate in the aperture-on-dielectric-substrate configuration. We also show that, similar to a metal nanoparticle, an increase in the medium dielectric constant results in a red-shift in the plasmon resonance of a nanoscale ridge aperture. These results, which are verified by a numerical analysis, provide a new understanding of the phenomenon of surface-plasmon-enhanced transmission. We demonstrate that the red-shifted wavelength and dielectric properties can compensate for the optical loss due to plasmon red-shift. In addition, the dielectric substrate layer behaves like a FabryPérot optical resonator, resulting in coherent constructive interference. The simulation results show that the |E|² intensity of the triangular aperture is 200% greater when this dielectric effect and red-shift resonance are considered.