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arXiv · 1508.06810

Cavity-enhanced Raman Microscopy of Individual Carbon Nanotubes

Thomas Hümmer·Jonathan Noe·Matthias S. Hofmann·Theodor W. Hänsch·Alexander Högele·David Hunger
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Abstract

Raman spectroscopy reveals chemically specific information and provides label-free insight into the molecular world. However, the signals are intrinsically weak and call for enhancement techniques. Here, we demonstrate Purcell enhancement of Raman scattering in a tunable high-finesse microcavity, and utilize it for molecular diagnostics by combined Raman and absorption imaging. Studying individual single-wall carbon nanotubes, we identify crucial structural parameters such as nanotube radius, electronic structure and extinction cross-section. We observe a 320-times enhanced Raman scattering spectral density and an effective Purcell factor of 6.2, together with a collection efficiency of 60%. Potential for significantly higher enhancement, quantitative signals, inherent spectral filtering and absence of intrinsic background in cavity-vacuum stimulated Raman scattering render the technique a promising tool for molecular imaging. Furthermore, cavity-enhanced Raman transitions involving localized excitons could potentially be used for gaining quantum control over nanomechanical motion and open a route for molecular cavity optomechanics.

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Thomas Hümmer, Jonathan Noe, Matthias S. Hofmann, Theodor W. Hänsch, Alexander Högele, David Hunger. 2016-07-13. Cavity-enhanced Raman Microscopy of Individual Carbon Nanotubes. https://doi.org/10.1038/ncomms12155

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