Flash Ablation of Tunable and Deep-Subwavelength Nanogap by Using a Spatially Modulated Femtosecond Laser Pulse for Plasmonic Application

Zhijie Xu, Lan Jiang, Xiaowei Li, Andong Wang, Bohong Li, Lingling Huang, Zemeng Lin, Ji Huang, Yongfeng Lu

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

The fabrication of gold nanostructures on a dielectric substrate with a nanogap between the opposite tips is suitable for the excitation of hot spots. In this study, a novel and efficient one-step method is reported for fabricating a gold bowtie nanogap by using a spatially shaped femtosecond laser pulse. The size of the nanogap could be flexibly controlled by adjusting the pulse energy. The smallest nanogap produced by the proposed method measures 30 nm (≈1/26 of the laser wavelength). The formation mechanism of the different morphologies is investigated. Combined with a phase- and amplitude-based beam-shaping technique, the bridge could be manipulated. Both experimental surface-enhanced Raman scattering spectra and simulated finite-difference time-domain results are used to characterize the plasmonic properties of the fabricated bowtie nanogap. The manufacturing scalability of the proposed method is demonstrated through the fabrication of a matrix of nanostructure, which exhibits great uniformity, achieving a density of 2.13 × 106 devices cm-2. Large-area microgaps can be patterned on a terahertz metasurface through the proposed method. The proposed technique provides a simple, flexible, and efficient alternative method for nanogap fabrication. The method can be extensively implemented in biosensing, photovoltaics, and nanophotonics.

Original languageEnglish (US)
Pages (from-to)4933-4941
Number of pages9
JournalACS Applied Nano Materials
Volume2
Issue number8
DOIs
StatePublished - Aug 23 2019

Keywords

  • bowtie nanogap
  • femtosecond laser ablation
  • plasmonic application
  • scalable fabrication
  • spatial light modulation

ASJC Scopus subject areas

  • Materials Science(all)

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