Directly patterned substrate-free plasmonic "nanograter" structures with unusual Fano resonances

Ajuan Cui, Zhe Liu, Jiafang Li, Tiehan H. Shen, Xiaoxiang Xia, Zhiyuan Li, Zhijie Gong, Hongqiang Li, Benli Wang, Junjie Li, Haifang Yang, Wuxia Li*, Changzhi Gu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

105 Citations (Scopus)

Abstract

The application of three-dimensional (3D) plasmonic nanostructures as metamaterials (MMs), nano-antennas, and other devices faces challenges in producing metallic nanostructures with easily definable orientations, sophisticated shapes, and smooth surfaces that are operational in the optical regime and beyond. Here, we demonstrate that complex 3D nanostructures can be readily achieved with focused-ion-beam irradiation-induced folding and examine the optical characteristics of plasmonic "nanograter" structures that are composed of free-standing Au films. These 3D nanostructures exhibit interesting 3D hybridization in current flows and exhibit unusual and well-scalable Fano resonances at wavelengths ranging from 1.6 to 6.4 μm. Upon the introduction of liquids of various refractive indices to the structures, a strong dependence of the Fano resonance is observed, with spectral sensitivities of 1400 nm and 2040 nm per refractive index unit under figures of merit of 35.0 and 12.5, respectively, for low-order and high-order resonance in the near-infrared region. This work indicates the exciting, increasing relevance of similarly constructed 3D free-standing nanostructures in the research and development of photonics and MMs.

Original languageEnglish
Article numbere308
JournalLight: Science and Applications
Volume4
Issue number7
DOIs
Publication statusPublished - 3 Jul 2015
Externally publishedYes

Keywords

  • Extraordinary Fano resonances
  • Plasmonic nanostructures
  • Spatially oriented
  • Substrate-free
  • Three-dimensional

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