High dispersion and bistability of the light transmission through a bilayer metasurface with resonant plasmonic elements

Abstract

The optical response of the bilayer metasurface consisting of thin gold nanobars featuring localized plasmon resonance was considered. Detailed theoretical and numerical analysis demonstrates that a sharp narrow dip in the transmittance spectrum of the metasurface can be observed when the layer-to-layer coupling is taken into account. Here gold nanobars, supporting localized plasmon modes, act as open resonators giving rise to the interaction of the unit-cell elements in adjacent layers. Through a careful choice of the geometrical parameters of the metasurface, one can achieve resonance in the near-infrared spectrum with a linewidth as narrow as 4 nm, and resonant values of the transmittance and reflectance of 0.06 and 0.46, respectively. The resonance accompanied by a noticeable increase in the wave field intensity in the interlayer area creates favorable conditions to boost nonlinear processes thus enabling all-optical light control and optical bistability.