Electric current induced unidirectional propagation of surface plasmon-polaritons

TL;DR

This paper introduces a novel method to achieve unidirectional surface plasmon-polariton propagation using electric currents in metals, leveraging Doppler shifts to control SPP dispersion without magnetic fields.

Contribution

It demonstrates a new approach to control SPP directionality via electric current-induced Doppler shifts, avoiding magneto-optical effects.

Findings

Electric current causes Doppler shifts in SPPs.

Unidirectional propagation is achieved at metal-dielectric interfaces.

Zero and negative group velocities of SPPs are demonstrated.

Abstract

Nonreciprocity and one-way propagation of optical signals is crucial for modern nanophotonic technology, and is typically achieved using magneto-optical effects requiring large magnetic biases. Here we suggest a fundamentally novel approach to achieve unidirectional propagation of surface plasmon-polaritons (SPPs) at metal-dielectric interfaces. We employ a direct electric current in metals, which produces a Doppler frequency shift of SPPs due to the uniform drift of electrons. This tilts the SPP dispersion, enabling one-way propagation, as well as zero and negative group velocities. The results are demonstrated for planar interfaces and cylindrical nanowire waveguides.