Nanophotonics (Jun 2019)

Bio-inspired plasmonic leaf for enhanced light-matter interactions

  • Liu Changxu,
  • Mao Peng,
  • Guo Qinghua,
  • Han Min,
  • Zhang Shuang

DOI
https://doi.org/10.1515/nanoph-2019-0104
Journal volume & issue
Vol. 8, no. 7
pp. 1291 – 1298

Abstract

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The mathematical concept of fractals is widely applied to photonics as planar structures ranging from terahertz resonators, optical antennas, to photodetectors. Here, instead of a direct mathematical abstract, we design a plasmonic leaf with fractal geometry from the outline of a leaf from Wargrave Pink. The enhanced light-matter interactions are observed numerically from the improvement in both absorption and near-field intensification. To demonstrate the effect experimentally, a three-dimensional fractal structure is realised through direct laser writing, which significantly improves the photothermal conversion. By virtue of the self-similarity in geometry, the artificial leaf improves the absorption of a 10-nm-thick gold film with 14 × temperature increment compared to flat Au film. Not limited to the proof-of-concept photothermal experiment demonstrated here, the fractal structure with improved light-matter interactions can be utilised in a variety of applications ranging from non-linear harmonic generation, plasmonic-enhanced fluorescence, to hot electron generation for photocatalysis.

Keywords