Quasi-Relativistic Doppler Effect and Non-Reciprocal Plasmons in Graphene

TL;DR

This paper introduces a novel method to achieve optical nonreciprocity at the nanoscale using the plasmonic Doppler effect in graphene, enabling one-way plasmon modes without magnetic fields.

Contribution

It demonstrates how DC current in graphene can induce strong nonreciprocal plasmonic effects, including mode isolation and resonance splitting, advancing optoelectronic and plasmonic device design.

Findings

Large carrier drift velocities enable nonreciprocal modes.

DC current induces plasmon resonance splitting.

One-way transmission demonstrated in Mach-Zehnder interferometers.

Abstract

Strong optical nonreciprocity at the nanoscale, relying on extreme one-way modes and backscattering suppression, can enable fundamentally new approaches in optoelectronics and plasmonics. Of special interest is achieving nonreciprocity in systems devoid of magnetic couplings. We describe a new approach based on the plasmonic Doppler effect which takes place for plasmons propagating in the presence of an electrical DC current. Large carrier drift velocities reachable in high-mobility electron systems, such as graphene, can enable strongly nonreciprocal or even fully one-way modes. Striking effects such as mode isolation and one-way transmission in DC-current-controlled Mach-Zehnder interferometers provide clear manifestations of plasmonic nonreciprocity. Phenomena such as plasmon resonance splitting into a doublet, induced by a DC current, afford new ways to generate and exploit unidirectionally propagating plasmon modes.