Gradient-index nanophotonics

TL;DR

This paper introduces a new class of low-loss surface electromagnetic waves that can propagate along lossy media with a continuous permittivity gradient, enabling applications in nanophotonics and underwater communication.

Contribution

It presents the discovery of a novel surface wave type supported by a broad range of lossy media, expanding potential applications beyond traditional plasmonics.

Findings

Surface waves can propagate with shorter wavelengths than free-space light.

Supported by various lossy media like graphite and sandy seabed.

Potential applications in super-resolution imaging, nanolithography, and underwater communication.

Abstract

It is demonstrated that a new kind of low-loss surface electromagnetic wave may propagate along a planar surface inside a lossy medium if the medium permittivity changes continuously across such surface. Similar to surface plasmons, the wavelength of this wave may be considerably shorter than the light wavelength in free space, which may enable its applications in super-resolution microscopy and nanolithography techniques. However, unlike plasmonics-based nanophotonic devices, which are typically built using a very limited number of low loss optical materials, the newly found class of surface waves may be supported by a much broader range of lossy media. Such materials as graphite seems to be ideal in UV nanophotonics applications. On the opposite side of the electromagnetic spectrum, similar long-range surface electromagnetic radio waves are capable of propagating underwater along a sandy seabed, which may enable efficient underwater radio communication and imaging.