Alignment-insensitive bilayer THz metasurface absorbers exceeding 100% bandwidth

Kenney, M. , Grant, J. and Cumming, D. R.S. (2019) Alignment-insensitive bilayer THz metasurface absorbers exceeding 100% bandwidth. Optics Express, 27(15), pp. 20886-20900. (doi: 10.1364/OE.27.020886) (PMID:31510176)

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Metamaterial absorbers have been a topic of considerable interest in recent years, with a particular focus on Terahertz (THz) frequencies due to many natural materials having a weak interaction with THz light. Great efforts have aimed to expand such THz absorbers to cover a wide bandwidth whilst also being highly efficient. However, many of these require cascaded or stacked multilayer resonant elements, where even a small deviation in the alignment between layers is extremely detrimental to the performance. Here, we propose a bilayer metasurface absorber (thickness ∼ λ/6) that is immune to such layer misalignments capable of exceeding a fractional bandwidth (FWHM) of 100% of the central frequency. The design works due to a novel absorption mechanism based on Salisbury Screen and anti-reflection absorption mechanisms, using fractal cross absorbers to expand the bandwidth. Our work is of particular benefit to developing devices which require ultra-wide bandwidth, such as bolometric sensing and planar blackbody absorbers, with the extremely robust absorption responses being unaffected by any misalignments between layers – a limiting factor of previous absorbers.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Cumming, Professor David and Grant, Dr James and Kenney, Dr Mitchell Guy
Authors: Kenney, M., Grant, J., and Cumming, D. R.S.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Optics Express
Publisher:Optical Society of America
ISSN (Online):1094-4087
Published Online:11 July 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Optics Express 27(15):20886-20900
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
588332Triple wavelength superspectral camera focal-plane array (SUPERCAMERA)David CummingEngineering and Physical Sciences Research Council (EPSRC)EP/J018678/1ENG - ENGINEERING ELECTRONICS & NANO ENG
6672319UK Quantum Technology Hub in Enhanced Quantum ImagingMiles PadgettEngineering and Physical Sciences Research Council (EPSRC)EP/M01326X/1S&E P&A - PHYSICS & ASTRONOMY