title: Nonlinear Plasmonic Sensing.
abstract: We introduce the concept of nonlinear plasmonic sensing, relying on third harmonic generation from simple plasmonic nanoantennas. Because of the nonlinear conversion process we observe a larger sensitivity to a local change in the refractive index as compared to the commonly used linear localized surface plasmon resonance sensing. Refractive index changes as small as 10(-3) can be detected. In order to determine the spectral position of highest sensitivity, we perform linear and third harmonic spectroscopy on plasmonic nanoantenna arrays, which are the fundamental building blocks of our sensor. Furthermore, simultaneous detection of linear and nonlinear signals allows quantitative comparison of both methods, providing further insight into the working principle of our sensor. While the signal-to-noise ratio is comparable, nonlinear sensing gives about seven times higher relative signal changes.
authors.affiliation: 4th Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Mesch
authors.affiliation: 4th Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Metzger
authors.affiliation: 4th Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Hentschel
authors.affiliation: 4th Physics Institute and Research Center SCoPE, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Giessen
keywords: Nanooptics; nonlinear optics; plasmonics; refractive index sensing