Controlling the Infrared Dielectric Function through Atomic-Scale Heterostructures

TL;DR

This paper introduces a method to engineer the infrared dielectric function by using atomic-scale heterostructures of GaN and AlN, enabling tunable surface phonon polaritons beyond traditional spectral limits.

Contribution

It demonstrates a novel atomic-scale superlattice approach to control and extend the spectral range of surface phonon polaritons in the infrared.

Findings

Created a hybrid dielectric with tunable phonon modes

Extended the spectral range of SPhPs beyond natural limits

Provided design principles for dielectric function engineering

Abstract

Surface phonon polaritons (SPhPs) - the surface-bound electromagnetic modes of a polar material resulting from the coupling of light with optic phonons - offer immense technological opportunities for nanophotonics in the infrared (IR) spectral region. Here, we present a novel approach to overcome the major limitation of SPhPs, namely the narrow, material-specific spectral range where SPhPs can be supported, called the Reststrahlen band. We use an atomic-scale superlattice (SL) of two polar semiconductors, GaN and AlN, to create a hybrid material featuring layer thickness-tunable optic phonon modes. As the IR dielectric function is governed by the optic phonon behavior, such control provides a means to create a new dielectric function distinct from either constituent material and to tune the range over which SPhPs can be supported. This work offers the first glimpse of the guiding principles governing the degree to which the dielectric function can be designed using this approach.