Cavity-enhanced optical detection of carbon nanotube Brownian motion

TL;DR

This paper demonstrates the use of a fiber-based high-finesse optical microcavity to detect the Brownian motion of a suspended carbon nanotube at room temperature, achieving high sensitivity and spectral characterization.

Contribution

It introduces a novel optical cavity technique for detecting nanomechanical motion of carbon nanotubes at room temperature with high precision.

Findings

Detection of nanotube deflections down to 50pm/Hz^1/2

Full vibrational spectrum obtained and verified by electron microscopy

Extension of optomechanical detection to molecular-scale systems

Abstract

Optical cavities with small mode volume are well-suited to detect the vibration of sub-wavelength sized objects. Here we employ a fiber-based, high-finesse optical microcavity to detect the Brownian motion of a freely suspended carbon nanotube at room temperature under vacuum. The optical detection resolves deflections of the oscillating tube down to 50pm/Hz^1/2. A full vibrational spectrum of the carbon nanotube is obtained and confirmed by characterization of the same device in a scanning electron microscope. Our work successfully extends the principles of high-sensitivity optomechanical detection to molecular scale nanomechanical systems.