Huge local field enhancement in perfect plasmonic absorbers

TL;DR

This paper theoretically demonstrates that perfect light absorption in a thin plasmonic structure can be achieved through simultaneous electric and magnetic resonances, leading to significant local field enhancement.

Contribution

It introduces a novel approach using substrate-induced bianisotropy to enable total absorption and local field enhancement in a zero-thickness planar structure.

Findings

Total power absorption is achievable with electric and magnetic mode resonance.

Substrate-induced bianisotropy enhances magnetic response and local fields.

Maximal absorption coincides with peak local field enhancement.

Abstract

In this Letter we theoretically study the possibility of total power absorption of light in a planar grid modelled as an effective sheet with zero optical thickness. The key prerequisite of this effect is the simultaneous presence of both resonant electric and magnetic modes in the structure. We show that the needed level of the magnetic mode is achievable using the effect of substrate-induced bianisotropy which also allows the huge local field enhancement at the same wavelength where the maximal absorption holds.