Ultralong Lifetime Plasmons on Picosecond Time Scale Enabled by Hybrid Plasmon-Phonon Polaritons

TL;DR

This paper reports the discovery of a hybrid plasmon-phonon polariton mode in graphene/h-BN heterostructures that achieves an ultralong plasmon lifetime of 1.6 picoseconds, enabling advancements in low-loss, high-speed optical devices.

Contribution

It introduces a novel hybrid mode in graphene/h-BN heterostructures that significantly extends plasmon lifetime, offering new control over plasmon behavior for optical applications.

Findings

Achieved a plasmon lifetime of 1.6 ps, the longest reported.

Discovered hybridized plasmon-phonon polariton mode in graphene/h-BN.

Potential for ultra-low-loss, high-speed optical devices.

Abstract

Graphene plasmonics is of great interest for compact optical devices working in broad frequency domains with ultrahigh speed and very low energy consumption. However, graphene plasmons damp out quickly on most substrates mainly due to scattering loss from substrate surface phonons and impurities. Here we discover a new hybridized plasmon-phonon polariton mode in graphene/h-BN van der Waals heterostructures, which enables ultralong hybrid plasmon lifetime up to 1.6 picosecond, the longest plasmon lifetime ever demonstrated. Such remarkably long lifetime arises from the coupling of long-lifetime h-BN transverse optical phonon with graphene plasmons, which uniquely exists in monolayer heterostructures. Our findings and understanding of this unexploited hybrid mode offer a novel approach to tune the plasmon behaviours in the frequency, time and space domains. This can potentially introduce a new paradigm to generate highly-confined plasmons with ultra-long lifetime for various applications, such as deep-subwavelength metamaterials, ultra-low-loss waveguides, and ultrafast optical switches.