Exciton-Plasmon Interactions in Individual Carbon Nanotubes

TL;DR

This paper investigates exciton-plasmon interactions in individual carbon nanotubes, revealing strong coupling effects, controllable via electric fields, and implications for advanced optoelectronic and nano-electromechanical devices.

Contribution

It introduces a quantum electrodynamics framework to analyze exciton-surface-plasmon interactions and demonstrates tunable coupling and force effects in single- and double-wall carbon nanotubes.

Findings

Strong exciton-surface-plasmon coupling with Rabi splitting ~0.1 eV.

Electrostatic fields can control exciton-plasmon interactions.

Inter-tube Casimir forces are significantly affected by plasmon resonances.

Abstract

We use the macroscopic quantum electrodynamics approach suitable for absorbing and dispersing media to study the properties and role of collective surface excitations --- excitons and plasmons --- in single-wall and double-wall carbon nanotubes. We show that the interactions of excitonic states with surface electromagnetic modes in individual small-diameter (<~1 nm) single-walled carbon nanotubes can result in strong exciton-surface-plasmon coupling. Optical response of individual nanotubes exhibits Rabi splitting ~0.1 eV, both in the linear excitation regime and in the non-linear excitation regime with the photoinduced biexcitonic states formation, as the exciton energy is tuned to the nearest interband surface plasmon resonance of the nanotube. An electrostatic field applied perpendicular to the nanotube axis can be used to control the exciton-plasmon coupling. For double-wall carbon nanotubes, we show that at tube separations similar to their equilibrium distances interband surface plasmons have a profound effect on the inter-tube Casimir force. Strong overlapping plasmon resonances from both tubes warrant their stronger attraction. Nanotube chiralities possessing such collective excitation features will result in forming the most favorable inner-outer tube combination in double-wall carbon nanotubes. These results pave the way for the development of new generation of tunable optoelectronic and nano-electromechanical device applications with carbon nanotubes.