Active spatial control of terahertz graphene plasmons by tailoring carrier density profile

TL;DR

This paper demonstrates full electrical control of terahertz graphene plasmons by tailoring carrier density profiles with a dual gate, enabling programmable plasmonic circuits and precise control over plasmon confinement and propagation.

Contribution

It introduces a dual-gate design that minimizes dielectric effects, allowing continuous control of plasmon reflection and transmission in graphene.

Findings

Plasmon reflection varies with carrier density difference.

Size, position, and frequency of plasmon cavities can be controlled.

The method enables programmable plasmonic circuits.

Abstract

Graphene offers a possibility for actively controlling plasmon confinement and propagation by tailoring its spatial conductivity pattern. However, implementation of this concept has been hampered because uncontrollable plasmon reflection is easily induced by inhomogeneous dielectric environment. In this work, we demonstrate full electrical control of plasmon reflection/transmission at electronic boundaries induced by a zinc-oxide-based dual gate, which is designed to minimize the dielectric modulation. Using Fourier-transform infrared spectroscopy, we show that the plasmon reflection can be varied continuously with the carrier density difference between the adjacent regions. By utilizing this functionality, we show the ability to control size, position, and frequency of plasmon cavities. Our approach can be applied to various types of plasmonic devices, paving the way for implementing a programmable plasmonic circuit.