Silicon Nanowire on Mirror Nanoantennas: Engineering Hybrid Gap Mode for Light Sources and Sensing Platforms

Abstract

It has been demonstrated recently that a nanowire (NW) of high refractive index dielectric materials works as a nanoantenna because of the excitation of the Mie-type resonances. Here, we explore the capability of a silicon (Si) NW as an optical nanoantenna by combining it with an external metallic component. We investigate the light scattering property of a single Si NW placed on a gold (Au) mirror via a very thin dielectric spacer and demonstrate strong confinement of electromagnetic fields in the gap because of the coupling of the resonance modes with a Au mirror. We demonstrate that the resonance wavelength of the hybrid mode can be tuned by the gap length, and the hybrid gap mode strongly modifies the spectral shape of the emission from a quantum dot (QD) monolayer incorporated in the gap. Quantitative analyses of the data in combination with numerical simulations reveal that the enhancement and the polarization control of the QD emission are achieved by the coupling.