Coherent Perfect Diffraction in Metagratings

Metasurfaces are 2D engineered structures with subwavelength granularity, offering a wide range of opportunities to tailor the impinging wavefront. However, fundamental limitations on their efficiency in wave transformation, associated with their deeply subwavelength thickness, challenge their imple...

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Bibliographic Details
Published in:Advanced materials (Weinheim) 2020-09, Vol.32 (36), p.e2002341-n/a
Main Authors: Zhang, Ziying, Kang, Ming, Zhang, Xueqian, Feng, Xi, Xu, Yuehong, Chen, Xieyu, Zhang, Huifang, Xu, Quan, Tian, Zhen, Zhang, Weili, Krasnok, Alex, Han, Jiaguang, Alù, Andrea
Format: Article
Language:English
Subjects:
Bandwidths
Broadband
Coherence
coherent control
Diffraction
Diffraction efficiency
Efficiency
Energy distribution
Excitation
metagratings
terahertz
Terahertz frequencies
Wave fronts
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Summary:Metasurfaces are 2D engineered structures with subwavelength granularity, offering a wide range of opportunities to tailor the impinging wavefront. However, fundamental limitations on their efficiency in wave transformation, associated with their deeply subwavelength thickness, challenge their implementation in practical application scenarios. Here, it is shown how the coherent control of metagratings through multiple wave excitations can provide new opportunities to achieve highly reconfigurable broadband metasurfaces with large diffraction efficiency, beyond the limitations of conventional approaches. Remarkably, energy distribution between the 0th and higher diffraction orders can be continuously tuned by changing the relative phase difference between two excitation waves, enabling coherent control, with added benefits of enhanced efficiency and bandwidth. This concept is demonstrated for a thin electric metagrating operating at terahertz frequencies, showing that coherent control can overcome several of the limitations of single‐layer ultrathin metastructures, and extend their feasibility in various practical scenarios. Coherent control of metagratings through multiple wave excitations is shown to provide new opportunities for highly reconfigurable broadband metasurfaces with unitary diffraction efficiency.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.202002341