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Proceedings Paper

Wavelength-dependent third harmonic generation in plasmonic gold nanoantennas: quantitative determination of the d-band influence (Conference Presentation)
Author(s): Joachim Krauth; Harald Giessen; Mario Hentschel

Paper Abstract

Plasmonic gold nanoantennas are highly efficient nanoscale nonlinear light converters. The nanoantennas provide large resonant light interaction cross sections as well as strongly enhanced local fields. The actual frequency conversion, however, takes places inside the gold volume and is thus ultimately determined by the microscopic gold nonlinearity which has been found to significantly surpass common bulk nonlinear materials. While the influence of the nanoantenna geometry and hence the plasmonic resonance has been studied in great detail, only little attention has been paid to the microscopic material nonlinearity. Here we show that the microscopic third-order nonlinearity of gold is in fact a resonant one by virtue of interband transitions between the d- and sp-bands. Utilizing a large set of resonant nanoantennas and a fiber-feedback optical parametric oscillator as broadband tunable light source, we show that the radiated third-harmonic signals significantly increase at the onset of interband transitions, namely, as soon as the third harmonic becomes resonant with allowed interband transitions. With the help of an anharmonic oscillator model and independent reference measurements on a gold film we can unambiguously demonstrate that the observed third-harmonic increase is related to a strongly wavelength-dependent microscopic third-order gold nonlinearity, which is additionally underlined by quantitative agreement between simulation and measurement. This additional tuning parameter allows further manipulation and optimization of nonlinear nanoscale systems and thus renders the investigation of other plasmonic materials, especially with interband transitions located in the ultra-violet range, highly intriguing.

Paper Details

Date Published: 17 September 2018
Proc. SPIE 10719, Metamaterials, Metadevices, and Metasystems 2018, 1071908 (17 September 2018); doi: 10.1117/12.2502219
Show Author Affiliations
Joachim Krauth, 4th Physics Institute and Research Ctr. SCoPE (Germany)
Harald Giessen, 4th Physics Institute and Research Ctr. SCoPE (Germany)
Mario Hentschel, 4th Physics Institute and Research Ctr. SCoPE (Germany)

Published in SPIE Proceedings Vol. 10719:
Metamaterials, Metadevices, and Metasystems 2018
Nader Engheta; Mikhail A. Noginov; Nikolay I. Zheludev, Editor(s)

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