Nanoantenna-enhanced ultrafast nonlinear spectroscopy of a single gold nanoparticle

• Published in: Nature communications Vol. 2; no. 1; p. 333
• Main Authors: Schumacher, Thorsten, Kratzer, Kai, Molnar, David, Hentschel, Mario, Giessen, Harald, Lippitz, Markus
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31.05.2011; Nature Publishing Group
• Subjects: 639/624/400/584; 639/925/350/354; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms1334

Optical nanoantennas, just like their radio-frequency equivalents, enhance the light-matter interaction in their feed gap. Antenna enhancement of small signals promises to open a new regime in linear and nonlinear spectroscopy on the nanoscale. Without antennas especially the nonlinear spectroscopy of single nanoobjects is very demanding. Here we present the first antenna-enhanced ultrafast nonlinear optical spectroscopy. In particular, we use the antenna to determine the nonlinear transient absorption signal of a single gold nanoparticle caused by mechanical breathing oscillations. We increase the signal amplitu-de by an order of magnitude, which is in good agreement with our analytical and numerical models. Our method will find applications in linear and nonlinear spectroscopy of single nanoobjects, especially in simplifying such challenging experiments as transient absorption or multiphoton excitation. Optical nanoantennas can be used for spectroscopic investigations at previously unattainable dimensions. Schumacher et al. describe time-resolved antenna-enhanced ultrafast nonlinear optical spectroscopy and determine the transient absorption signal of a single gold nanoparticle.