ISBN 9783843943147

978-3-8439-4314-7, Reihe Physik

Joachim Krauth
Nonlinear Spectroscopy of Complex Plasmonic Nanostructures

220 Seiten, Dissertation Universität Stuttgart (2019), Softcover, A5

Zusammenfassung / Abstract

The aim of this thesis is to develop an optical setup for nonlinear spectroscopy and to conduct spectroscopic measurements with it.

In order to perform nonlinear spectroscopy experiments on plasmonic nanostructures, a tunable optical parametric oscillator for the near-infrared spectral region was set up. The femtosecond pulse duration and the broad tuning range renders this source an ideal light source for the illumination of plasmonic nanostructures.

With this setup, the spectral dependence of the intrinsic gold nonlinearity, which exhibits a strong wavelength dependence due to interband transitions of electrons from the 5d- to the 6sp-bands is unraveled.

Furthermore, the third harmonic response of a three-dimensional so-called dolmen-type structure is investigated. Here, excitation of an originally dark mode is enabled by coupling to a dipolar mode. We find a contribution in the third harmonic signal polarized along the quadrupole rods, which we assign to structural asymmetries resulting in a non-vanishing dipole moment of the originally dark mode, which hardly manifests itself in the linear regime, but is clearly visible in the nonlinear response. Thus, nonlinear investigations can help to resolve minor asymmetries in plasmonic systems.