Strong and broadly tunable plasmon resonances in thick films of aligned carbon nanotubes

TL;DR

This paper demonstrates that thick films of aligned carbon nanotubes exhibit strong, narrow, and tunable plasmon resonances in the near-infrared, with potential applications in infrared telecommunications.

Contribution

It introduces a method to fabricate thick, aligned carbon nanotube films with highly tunable and efficient plasmonic resonances in the near-infrared range.

Findings

Peak attenuation reaches 70% in the films.

Quality factors of the resonances reach 9.

Peak frequencies are electrostatically tunable by a factor of 2.3.

Abstract

Low-dimensional plasmonic materials can function as high quality terahertz and infrared antennas at deep subwavelength scales. Despite these antennas' strong coupling to electromagnetic fields, there is a pressing need to further strengthen their absorption. We address this problem by fabricating thick films of aligned, uniformly sized carbon nanotubes and showing that their plasmon resonances are strong, narrow, and broadly tunable. With thicknesses ranging from 25 to 250 nm, our films exhibit peak attenuation reaching 70%, quality factors reaching 9, and electrostatically tunable peak frequencies by a factor of 2.3x. Excellent nanotube alignment leads to the attenuation being 99% linearly polarized along the nanotube axis. Increasing the film thickness blueshifts the plasmon resonators down to peak wavelengths as low as 1.4 micrometers, promoting them to a new near-infrared regime in which they can both overlap the S11 nanotube exciton energy and access the technologically important infrared telecom band.