Second harmonic generation hotspot on a centrosymmetric smooth silver surface

Matan Galanty, Omer Shavit, Adam Weissman, Hannah Aharon, David Gachet, Elad Segal, Adi Salomon

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Second harmonic generation (SHG) is forbidden for materials with inversion symmetry, such as bulk metals. Symmetry can be broken by morphological or dielectric discontinuities, yet SHG from a smooth continuous metallic surface is negligible. Using non-linear microscopy, we experimentally demonstrate enhanced SHG within an area of smooth silver film surrounded by nanocavities. Nanocavity-assisted SHG is locally enhanced by more than one order of magnitude compared to a neighboring silver surface area. Linear optical measurements and cathodoluminescence (CL) imaging substantiate these observations. We suggest that plasmonic modes launched from the edges of the nanocavities propagate onto the smooth silver film and annihilate, locally generating SHG. In addition, we show that these hotspots can be dynamically controlled in intensity and location by altering the polarization of the incoming field. Our results show that switchable nonlinear hotspots can be generated on smooth metallic films, with important applications in photocatalysis, single-molecule spectroscopy and non-linear surface imaging.

Original languageEnglish
Article number49
JournalLight: Science and Applications
Volume7
Issue number1
DOIs
StatePublished - 1 Dec 2018

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© 2018, The Author(s).

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