Driving plasmonic nanoantennas at perfect impedance matching using generalized coherent perfect absorption

TL;DR

This paper introduces a generalized coherent perfect absorption (gCPA) method for plasmonic nanoantennas, enabling perfect impedance matching and efficient energy absorption by controlling specific plasmonic modes, with applications in sensing.

Contribution

The paper extends CPA to include radiative losses in plasmonic nanoantennas, demonstrating perfect impedance matching between a nanowire waveguide and a nanoantenna.

Findings

Achieved perfect impedance matching using gCPA.

Controlled absorption of specific plasmonic modes.

Potential for background-free sensing applications.

Abstract

Coherent perfect absorption (CPA) describes the absence of all outgoing modes from a lossy resonator, driven by lossless incoming modes. Here, we show that for nanoresonators that also exhibit radiative losses, e.g. plasmonic nanoantennas, a generalized version of CPA (gCPA) can be applied. In gCPA outgoing modes are sup-pressed only for a subset of (guided plasmonic) modes while other (radiative) modes are treated as additional loss channels - a situation typically referred to as perfect impedance matching. Here we make use of gCPA to show how to achieve perfect impedance matching between a single nanowire plasmonic waveguide and a plasmonic nanoantenna. Antennas with both radiant and subradiant characteristics are considered. We further demonstrate potential applications in background-free sensing.