期刊
LIGHT-SCIENCE & APPLICATIONS
卷 6, 期 -, 页码 -出版社
CHINESE ACAD SCIENCES, CHANGCHUN INST OPTICS FINE MECHANICS AND PHYSICS
DOI: 10.1038/lsa.2017.75
关键词
disorder-induced plasmon localization; nanoantennas; nanoporous gold nanoparticles; ultrafast photoemission spectroscopy
类别
资金
- Deutsche Forschungsgemeinschaft [LI 580/12, RU 1383/5, SCHA 632/24, SPP1839]
- Korea Foundation for the International Cooperation of Science and Technology (Global Research Laboratory) [K20815000003]
- German-Israeli Foundation (GIF) [1256]
- Studienstiftung des Deutschen Volkes
We report long-lived, highly spatially localized plasmon states on the surface of nanoporous gold nanoparticles-nanosponges-with high excitation efficiency. It is well known that disorder on the nanometer scale, particularly in two-dimensional systems, can lead to plasmon localization and large field enhancements, which can, in turn, be used to enhance nonlinear optical effects and to study and exploit quantum optical processes. Here, we introduce promising, three-dimensional model systems for light capture and plasmon localization as gold nanosponges that are formed by the dewetting of gold/ silver bilayers and dealloying. We study light-induced electron emission from single nanosponges, a nonlinear process with exponents of n approximate to 5...7, using ultrashort laser pulse excitation to achieve femtosecond time resolution. The long-lived electron emission process proves, in combination with optical extinction measurements and finite-difference time-domain calculations, the existence of localized modes with lifetimes of more than 20 fs. These electrons couple efficiently to the dipole antenna mode of each individual nanosponge, which in turn couples to the far-field. Thus, individual gold nanosponges are cheap and robust disordered nanoantennas with strong local resonances, and an ensemble of nanosponges constitutes a meta material with a strong polarization independent, nonlinear response over a wide frequency range.
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