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O: Fachverband Oberflächenphysik

O 14: Plasmonics and Nanooptics II: Light-Matter Interaction and Spectroscopy

O 14.8: Talk

Monday, March 18, 2024, 17:00–17:15, MA 042

Spatially resolved nonlinear plasmonics — •Florian Mangold, Johannes Schust, Mario Hentschel, Bettina Frank, and Harald Giessen — 4th Physics Institute, Research Center SCoPE, and IQST, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany

The nonlinear behavior of plasmonic nanoantenna arrays can be investigated using nonlinear spectroscopy. In our contribution we introduce nonlinear spatially resolved spectroscopy, which is capable of imaging the k-space behavior and the spectral behavior of nonlinear nanoantenna signals, as well as to spatially resolve the nonlinear signal of single nanoantennas.

These additional abilities give us the possibility to spatially resolve the THG signal of gold nanoantenna arrays and investigate the homogeneity of the antenna field. Furthermore, we are able to spatially resolve the THG emission centers of the third-order mode and observe their response to tuning the wavelength over the resonance.

In addition, we discovered that by increasing the laser intensity, certain antennas in our array became exceptionally bright. By correlating our spatially resolved nonlinear image with structural SEM data, we can prove that these bright antennas have deformed into a peanut shape. Thus our NSRS setup enables the investigation of the nonlinear self-enhancement process of nanoantennas under intense laser heating. We also simulated these peanut shaped antennas and could observe that these 3-dimensional structures lead to the enhancement of the nonlinear emission.

Keywords: nonlinear plasmonics; nonlinear spatially resolved spectroscopy; NSRS setup; third-order mode; self-enhancement of nanoantennas