Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Plasmonics II (joint session O/CPP)

CPP 27.3: Vortrag

Dienstag, 2. April 2019, 14:30–14:45, H8

Wavelength-dependent Third Harmonic Generation in Metallic Thin Films — •Vincent Drechsler, Joachim Krauth, Mario Hentschel, and Harald Giessen — 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany

Harmonic generation in plasmonic systems has gained significant interest in the last years. While the plasmonic near-field enhancement has been studied in great detail, little attention was paid to the origin of the nonlinear signals which in fact lie in the microscopic nonlinearity of the involved plasmonic metals. In order to predict wavelength-dependent nonlinear processes it is therefore crucial to understand these microscopic nonlinearities. Utilizing an optical parametric oscillator as a tunable broadband light source, we study wavelength-dependent third harmonic generation from metallic thin films made of Gold, Copper, and Magnesium. We find that the linear properties of the metallic films, that is their absorption, strongly influence the third harmonic generation efficiency. Optical transitions between the different bands lead to a resonant enhancement of the third order susceptibilities. Utilizing hydrogen to switch metallic magnesium to dielectric magnesium hydride we can tune the nonlinearity of thin films and observe the metallic-dielectric phase transition in the linear and nonlinear regime. We find complex relations between the linear transmittance and the radiated third harmonic, which provide new insights into the phase transition.