Tailored nano-antennas for directional Raman studies of individual carbon nanotubes

TL;DR

This paper presents a novel nano-antenna fabrication method that enhances and controls Raman signals from individual carbon nanotubes, enabling better optical detection and potential integrated device applications.

Contribution

The study introduces a top-down nano-antenna fabrication approach that allows polarization control and signal enhancement for Raman spectroscopy of CNTs, surpassing tip-based methods.

Findings

Nano-antennas significantly enhance Raman signals from CNTs.

The method allows precise control of light polarization in the sample plane.

Numerical simulations confirm the effectiveness of the nano-antenna design.

Abstract

We exploit the near field enhancement of nano-antennas to investigate the Raman spectra of otherwise not optically detectable carbon nanotubes (CNTs). We demonstrate that a top-down fabrication approach is particularly promising when applied to CNTs, owing to the sharp dependence of the scattered intensity on the angle between incident light polarization and CNT axis. In contrast to tip enhancement techniques, our method enables us to control the light polarization in the sample plane, locally amplifying and rotating the incident field and hence optimizing the Raman signal. Such promising features are confirmed by numerical simulations presented here. The relative ease of fabrication and alignment makes this technique suitable for the realization of integrated devices that combine scanning probe, optical, and transport characterization.