White Light Generation and Anisotropic Damage in Gold Films near Percolation Threshold

Sergey M. Novikov, Christian Frydendahl, Jonas Beermann, Volodymyr Zenin, Nicolas Stenger, Victor Coello, N. Asger Mortensen, Sergey I. Bozhevolnyi*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Strongly enhanced and confined electromagnetic fields generated in metal nanostructures upon illumination are exploited in many emerging technologies by either fabricating sophisticated nanostructures or synthesizing colloid nanoparticles. Here we study effects driven by field enhancement in vanishingly small gaps between gold islands in thin films near the electrically determined percolation threshold. Optical explorations using two-photon luminescence (TPL) and near-field microscopies reveals supercubic TPL power dependencies with white-light spectra, establishing unequivocally that the strongest TPL signals are generated close to the percolation threshold films, and occurrence of extremely confined (∼30 nm) and strongly enhanced (∼100 times) fields at the illumination wavelength. For linearly polarized and sufficiently powerful light, we observe pronounced optical damage with TPL images being sensitive to both wavelength and polarization of illuminating light. We relate these effects to thermally induced morphological changes observed with scanning electron microscopy images. Exciting physics involved in light interaction with near-percolation metal films along with their straightforward and scalable one-step fabrication procedure promises a wide range of fascinating developments and technological applications within diverse areas of modern nanotechnology, from biomolecule optical sensing to ultradense optical data storage.

Original languageEnglish
JournalACS Photonics
Volume4
Issue number5
Pages (from-to)1207-1215
ISSN2330-4022
DOIs
Publication statusPublished - 2017

Keywords

  • field enhancement
  • linear and nonlinear light scattering from surfaces
  • metal optics
  • phase-resolved near-field microscopy
  • scanning microscopy
  • surface plasmons

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