Pronounced Fano Resonance in Single Gold Split Nanodisks with 15 nm Split Gaps for Intensive Second Harmonic Generation

Shi Zhang, Guang Can Li, Yiqin Chen, Xupeng Zhu, Shao Ding Liu, Dangyuan Lei, Huigao Duan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

82 Citations (Scopus)

Abstract

Single metallic nanostructures supporting strong Fano resonances allow more compact nanophotonics integration and easier geometrical control in practical applications such as enhanced spectroscopy and sensing. In this work, we designed a class of plasmonic split nanodisks that show pronounced Fano resonance comparable to that observed in widely studied plasmonic oligomer clusters. Using our recently developed "sketch and peel" electron-beam lithography, split nanodisks with varied diameter and split length were fabricated over a large area with high uniformity. Transmission spectroscopy measurements demonstrated that the fabricated structures with 15 nm split gap exhibit disk diameter and split length controlled Fano resonances in the near-infrared region, showing excellent agreement with simulation results. Together with the plasmon hybridization theory, in-depth full-wave analyses elucidated that the Fano resonances observed in the split nanodisks were induced by mode interference between the bright antibonding dipole mode of split disks and the subradiant mode supported by the narrow split gap. With the giant near-field enhancement enabled by the intensive Fano resonance at the tiny split gap, strong wavelength-dependent second harmonic generation was observed under near-infrared excitation. Our work demonstrated that single split nanodisks could serve as important building blocks for plasmonic and nanophotonic applications including sensing and nonlinear optics.
Original languageEnglish
Pages (from-to)11105-11114
Number of pages10
JournalACS Nano
Volume10
Issue number12
DOIs
Publication statusPublished - 27 Dec 2016

Keywords

  • Fano resonance
  • second harmonic generation
  • sketch and peel lithography
  • split disks
  • surface plasmon

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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