Tunable Fano Resonances in an Ultra-Small Gap

Fuqiang Yao; Fang Li; Zhicong He; Yahui Liu; Litu Xu; Xiaobo Han

doi:10.3390/app10072603

Applied Sciences (Apr 2020)

Tunable Fano Resonances in an Ultra-Small Gap

Fuqiang Yao,
Fang Li,
Zhicong He,
Yahui Liu,
Litu Xu,
Xiaobo Han

Affiliations

Fuqiang Yao: Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China
Fang Li: Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China
Zhicong He: Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China
Yahui Liu: Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China
Litu Xu: Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China
Xiaobo Han: Hubei Key Laboratory of Optical Information and Pattern Recognition, School of Optical Information and Energy Engineering, School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China

DOI: https://doi.org/10.3390/app10072603
Journal volume & issue: Vol. 10, no. 7
p. 2603

Abstract

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A Fano resonance is experimentally observed in a single silver nanocube separated from a supporting silver film by a thin aluminum oxide film. The resonance spectrum is modulated by changing the size of the silver nanocube and its distance from the silver film. The system is fabricated by a bottom-up process with an accurately controlled nanogap at the sub-6-nm scale. The simulation result shows that the destructive interference between the dipole mode and the quadrupole mode in this “nanocube on mirror” (NCoM) structure is responsible for the resonance. The spectra red-shifted as the size of the silver nanocube increased and its distance from the silver film decreased. In addition, a refractive index sensitivity of the spectrum of 140 meV/RIU (refractive index unit), with a 2.4 figure of merit, is obtained by changing the dielectric environment around the silver nanocube. This work will enable the development of high-performance tunable optical nanodevices based on NCoM structures.

Published in Applied Sciences

ISSN: 2076-3417 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Engineering (General). Civil engineering (General); Science: Biology (General); Science: Physics; Science: Chemistry
Website: http://www.mdpi.com/journal/applsci

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