Strong exciton-plasmon coupling in semiconducting carbon nanotubes

TL;DR

This paper theoretically demonstrates strong exciton-plasmon coupling in semiconducting carbon nanotubes, showing Rabi splitting and potential for tunable optoelectronic devices.

Contribution

It reveals the possibility of strong exciton-surface-plasmon coupling in individual nanotubes and proposes control via the quantum confined Stark effect.

Findings

Rabi splitting of ~0.1 eV observed in absorption spectra.

Exciton energy can be tuned to plasmon resonance using the Stark effect.

Potential for new tunable optoelectronic applications.

Abstract

We study theoretically the interactions of excitonic states with surface electromagnetic modes of small-diameter (~1 nm) semiconducting single-walled carbon nanotubes. We show that these interactions can result in strong exciton-surface-plasmon coupling. The exciton absorption line shape exhibits Rabi splitting ~0.1 eV as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. We also show that the quantum confined Stark effect may be used as a tool to control the exciton binding energy and the nanotube band gap in carbon nanotubes in order, e.g., to bring the exciton total energy in resonance with the nearest interband plasmon mode. The exciton-plasmon Rabi splitting we predict here for an individual carbon nanotube is close in its magnitude to that previously reported for hybrid plasmonic nanostructures artificially fabricated of organic semiconductors on metallic films. We expect this effect to open up paths to new tunable optoelectronic device applications of semiconducting carbon nanotubes.