Pushing Photons with Electrons: Observation of the Polariton Drag Effect

TL;DR

This paper demonstrates that free electrons can influence polaritons in a cavity, enabling electrical control of photon emission angles, which could lead to new optoelectronic device functionalities.

Contribution

It provides the first direct observation of the polariton drag effect caused by electron-polariton interactions in a cavity system.

Findings

Electrons alter polariton momentum and emission angles.

The effect is asymmetric depending on electron and polariton directions.

A theoretical model explains the observed drag phenomenon.

Abstract

We show the direct effect of free electrons colliding with polaritons, changing their momentum. The result of this interaction of the electrons with the polaritons is a change in the angle of emission of the photons from our cavity structure. Because the experiment is a photon-in, photon-out system, this is equivalent to optical beam steering of photons using a direct electrical current. The effect is asymmetric, significantly slowing down the polaritons when they move oppositely to the electrons, while the polariton momentum only slightly increases when electrons moving in the same direction. We present a theoretical model which describes this effect.