Electrically Driven Highly Tunable Cavity Plasmons

Abstract

Electrically driven ultrafast plasmon sources with narrow line width and wide-range wavelength tunability are desirable choices for integrated nanophotonic circuits. These have a wide range of applications from the optical communication to the data processing. Here, we demonstrate a compact metal–insulator–metal tunneling junction as a plasmon source to meet these requirements simultaneously. It is consisted by a Ag nanowire (covered by a monolayer thiol molecular) cross-placed on a Au nanostripe. Cavity plasmons are excited by inelastic tunneling electrons as applying a bias voltage. The electroluminescence spectrum shows multiple peaks with line widths as narrow as tens of nanometers due to the excitation of third to fifth order cavity plasmon modes. The linearly tunable range of the third order cavity plasmon exceeds 200 nm by varying the diameter of the Ag nanowire ∼70 nm. Our work can be further developed for the multichannels and on-chip photonic light sources.