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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits

Professor

Portrait of Tönu Pullerits; Photo: Kennet Ruona

Evidence of High-Order Nonlinearities in Supercontinuum White-Light Generation from a Gold Nanofilm

Author

  • Junsheng Chen
  • Alexey Krasavin
  • Pavel Ginzburg
  • Anatoly V. Zayats
  • Tõnu Pullerits
  • Khadga Jung Karki

Summary, in English

White-light supercontinuum generation can be readily observed when gold nanostructures are irradiated with short pulses of light. It is believed that the nanostructures enhance the optical fields, which facilitates the supercontinuum white-light generation from the surrounding environment or the substrate. Here, we investigate the different nonlinear processes that contribute to the generation of the supercontinuum from plasmonic nanostructures themselves using a technique that isolates the different nonlinear contributions. By exciting a gold nanofilm with a pair of frequency shifted optical frequency combs, we demonstrate multiple modulation frequencies in the supercontinuum. Their dependence on the excitation intensity reveals that the supercontinuum originates from different orders of nonlinear light-matter interactions. This contrasts with the supercontinuum generation by a cascaded third-order optical nonlinear response in traditional dielectric-based white-light sources. The while-light emission from the gold nanofilm is efficient even under relatively weak excitation indicating that nonlocal effects in nanostructures may facilitate the supercontinuum generation by adding new pathways in the nonlinear interactions. The results provide experimental basis for the understanding of the collective nonlinear response of free-electrons in the metallic nanostructures and associated nonlinear processes, which are crucial in development of nonlinear metasurfaces and nanophotonic devices.

Department/s

  • Chemical Physics
  • NanoLund: Center for Nanoscience

Publishing year

2018-05-16

Language

English

Pages

1927-1932

Publication/Series

ACS Photonics

Volume

5

Issue

5

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Condensed Matter Physics
  • Atom and Molecular Physics and Optics

Keywords

  • nonlinear interactions
  • nonlocal response
  • rough metal films
  • white-light generation

Status

Published

ISBN/ISSN/Other

  • ISSN: 2330-4022