Broadband polarization-independent perfect absorber using a phase-change metamaterial at visible frequencies

Tun Cao*, Chen Wei Wei, Robert E. Simpson, Lei Zhang, Martin J. Cryan

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

172 Citations (Scopus)
254 Downloads (Pure)

Abstract

We report a broadband polarization-independent perfect absorber with wide-angle near unity absorbance in the visible regime. Our structure is composed of an array of thin Au squares separated from a continuous Au film by a phase change material (Ge 2 Sb 2 Te 5) layer. It shows that the near perfect absorbance is flat and broad over a wide-angle incidence up to 80for either transverse electric or magnetic polarization due to a high imaginary part of the dielectric permittivity of Ge 2 Sb 2 Te 5. The electric field, magnetic field and current distributions in the absorber are investigated to explain the physical origin of the absorbance. Moreover, we carried out numerical simulations to investigate the temporal variation of temperature in the Ge 2 Sb 2 Te 5 layer and to show that the temperature of amorphous Ge 2 Sb 2 Te 5 can be raised from room temperature to > 433â€...K (amorphous-to- crystalline phase transition temperature) in just 0.37†ns with a low light intensity of 95â€...nW/μm 2, owing to the enhanced broadband light absorbance through strong plasmonic resonances in the absorber. The proposed phase-change metamaterial provides a simple way to realize a broadband perfect absorber in the visible and near-infrared (NIR) regions and is important for a number of applications including thermally controlled photonic devices, solar energy conversion and optical data storage.

Original languageEnglish
Article number3955
JournalScientific Reports
Volume4
DOIs
Publication statusPublished - 4 Feb 2014

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