The impact of nonlocal response on metallo-dielectric multilayers and optical patch antennas

TL;DR

This paper investigates how nonlocal electronic responses influence waveguide modes in metallo-dielectric multilayers and optical patch antennas, highlighting the sensitivity of gap-plasmons to nonlocal effects at nanometer scales.

Contribution

It models both conduction and bound electron nonlocal effects and proposes optical patch antennas as a practical platform to measure nonlocality in metals.

Findings

Gap-plasmons are highly sensitive to nonlocality below 5 nm dielectric layers.

Optical patch antennas can be used to experimentally detect nonlocal effects.

Nonlocal effects significantly alter waveguide mode properties at nanometer scales.

Abstract

We analyze the impact of nonlocality on the waveguide modes of metallo-dielectric multilayers and optical patch antennas, the latter formed from metal strips closely spaced above a metallic plane. We model both the nonlocal effects associated with the conduction electrons of the metal, as well as the previously overlooked response of bound electrons. We show that the fundamental mode of a metal-dielectric-metal waveguide, sometimes called the gap-plasmon, is very sensitive to nonlocality when the insulating, dielectric layers are thinner than 5 nm. We suggest that optical patch antennas, which can easily be fabricated with controlled dielectric spacer layers and can be interrogated using far-field scattering, can enable the measurement of nonlocality in metals with good accuracy.