Realizing surface plasmon polariton modes with long lifetimes is the biggest challenge of contemporary plasmonics. Graphene sheets encapsulated between boron nitride crystals, which currently have the highest room-temperature dc mobility in the realm of two-dimensional materials, display amazingly long plasmon lifetimes in the mid-infrared spectral range, approaching 1 ps. Unfortunately, this is not yet enough for applications where vectoring confined optical signals over long distances is required (i.e. optical interconnects). In this talk, we will discuss a recent theoretical proposal where a fundamental materials science aspect of graphene, i.e. its capability to withstand large dc currents without burning, is utilized for increasing plasmon lifetimes. We will present extensive calculations of the plasmonic properties of a graphene sheet carrying a dc current. By employing a suitable random phase approximation, which is non-perturbative in the ratio between the drift velocity and the graphene Fermi velocity, we will show that graphene plasmons in the presence of a dc current display non-reciprocity and collimation. We truly hope that this all-electrical protocol will soon be demonstrated to yield a significant increase in graphene plasmon lifetimes.


Seminar, February 3, 2016, 12:00. Seminar Room

Hosted by Prof. Frank Koppens