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Chalcogenide–gold dual-layers coupled to gold nanoparticles for reconfigurable perfect absorption

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Abstract

Recently, tunable high absorptance from various nanophotonic structures has been demonstrated. However, most of these structures require nano-lithography, which is expensive and slow. Lithography-free tuneable absorbers are rarely explored for tuneable visible and near-infrared photonics. Herein, we demonstrate a gold (Au)/chalcogenide dual-layer that is resonantly coupled to Au nanoparticles (NPs). The structure exhibits angle and polarisation-independent high absorptance. At resonance, waveguide cavity-like modes are excited between the film and NPs whilst gap plasmon modes are excited between the NPs. Coalescence of the waveguide cavity-like modes, the gap plasmon modes, and the highly absorbing chalcogenide semiconductor not only leads to perfect absorptance but also a reconfigurable response via reversible structural phase transitions in the chalcogenide film. In the amorphous state, the design provides nearly perfect absorptance for both p- and s-polarisation states at an incident angle of 20°. However, after switching to the crystalline state, the peak absorptance spectrally broadens and redshifts from 980 to 1520 nm. This experimental observation was theoretically validated by the finite element method. Thermal-electric modeling was performed to show that the structural transition from crystalline to amorphous states is possible in just 5 ns, thus allowing high-speed reconfigurable perfect absorbers.

Graphical abstract: Chalcogenide–gold dual-layers coupled to gold nanoparticles for reconfigurable perfect absorption

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Publication details

The article was received on 05 Jun 2019, accepted on 05 Aug 2019 and first published on 09 Aug 2019


Article type: Paper
DOI: 10.1039/C9NR04759J
Nanoscale, 2019, Advance Article

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    Chalcogenide–gold dual-layers coupled to gold nanoparticles for reconfigurable perfect absorption

    T. Cao, K. Liu, L. Lu, H. Chui and R. E. Simpson, Nanoscale, 2019, Advance Article , DOI: 10.1039/C9NR04759J

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