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.
Original language | English |
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Pages (from-to) | 20546-20553 |
Number of pages | 8 |
Journal | Nanoscale |
Volume | 11 |
Issue number | 43 |
DOIs | |
Publication status | Published - 21 Nov 2019 |
Bibliographical note
Funding Information:This work was supported by the Singapore–China Joint Research Program (JRP) with grant number 2015DFG12630 from the International Science & Technology Cooperation Program of China and grant number 142020046 from the Singapore Agency for Science Technology and Research, A*Star. T. C. acknowledges support from the Program for Liaoning Excellent Talents in University (Grant No. LJQ2015021). L. L. is grateful for his Ministry of Education President’s Graduate Fellowship.
Publisher Copyright:
© The Royal Society of Chemistry.
ASJC Scopus subject areas
- General Materials Science