Space-time-coding digital metasurfaces

By Lei Zhang, X. Q. Chen, Shuo Liu, Qian Zhang, Jie Zhao, Jun Yan Dai, Guo Dong Bai, Xiang Wan, Qiang Cheng, G. Castaldi and 2 more. Nature Communications, 2018

1,136 citations recorded by the source corpus.

The recently proposed digital coding metasurfaces make it possible to control electromagnetic (EM) waves in real time, and allow the implementation of many different functionalities in a programmable way. However, current configurations are only space-encoded, and do not exploit the temporal dimension. Here, we propose a general theory of space-time modulated digital coding metasurfaces to obtain simultaneous manipulations of EM waves in both space and frequency domains, i.e., to control the propagation direction and harmonic power distribution simultaneously. As proof-of-principle application examples, we consider harmonic beam steering, beam shaping, and scattering-signature control. For validation, we realize a prototype controlled by a field-programmable gate array, which implements the harmonic beam steering via an optimized space-time coding sequence. Numerical and experimental results, in good agreement, demonstrate good performance of the proposed approach, with potential applications to diverse fields such as wireless communications, cognitive radars, adaptive beamforming, holographic imaging. Current digital coding metasurfaces are only space-encoded. Here, the authors propose space-time modulated digital coding metasurfaces to obtain simultaneous manipulations of electromagnetic waves and present harmonic beam steering, beam shaping, and scattering-signature control as application examples.

Subfields: Aerospace Engineering, Electronic, Optical and Magnetic Materials

View Paper: https://www.semanticscholar.org/paper/dc4ebdb47db84698be4947e9663ef04a8253867a

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Aerospace Engineering

In Electronic, Optical and Magnetic Materials

Citations in the corpus

Security and Privacy for 6G: A Survey on Prospective Technologies and Challenges (2021, background): “The preliminary results of the study in [147] indicate that, by controlling the propagation direction and harmonic power distribution simultaneously,”
Large Intelligent Surface-Assisted Wireless Communication Exploiting Statistical CSI (2018, background): “LIS is a cheap passive artificial structure that can digitally manipulate electromagnetic waves and obtain preferable electromagnetic propagation environment with limited power consumption [2], [3].”
Path Loss Modeling and Measurements for Reconfigurable Intelligent Surfaces in the Millimeter-Wave Frequency Band (2021, background): “An RIS is a thin surface that comprises a 52 large number of sub-wavelength unit cells that have the capa- 53 bility of modifying the phase and amplitude response on the 54 incident signals [8]–[10].”
Reconfigurable Intelligent Surfaces for Energy Efficiency in Wireless Communication (2018, background): “The RIS units operating on the incoming ﬁeld can be distributed over the meta-surface with continuity [14], [19], [20], [29] or in discrete positions [15], [22], [23], [30].”
6G and Beyond: The Future of Wireless Communications Systems (2020, methodology): “Common functions include wave steering, focusing, collimating (i.e., producing a planar wavefront as a response to an impinging wave), polarizing, phase altering, full or partial absorption, frequency selective ﬁltering and even modulation [60], [64].”
Toward Smart Wireless Communications via Intelligent Reflecting Surfaces: A Contemporary Survey (2019, background): “Realizing wave manipulations in both space and frequency domains, the authors in [69] design a space-time modulated digital coding metasurface to control the propagation direction and power distribution simultaneously in the frequency range of 8-10 GHz.”
Photonics of time-varying media (2021, methodology): “Recent implementations of frequency translation with metasurfaces have been recently carried out in the microwave regime,(102) and implementations with experimentally more practical discretized arrays of time- and space–time-modulated reactive elements are in steady development.(107,114) Several mor”
Phase-Induced Frequency Conversion and Doppler Effect With Time-Modulated Metasurfaces (2020, background): “interesting space–time-coding metasurfaces that are digitally controlled by an FPGA: in [49] the metasurface converts a normally impinging plane wave at frequency f0 in a set of waves at different harmonics f0+n fm , propagating in different directions.”
Dynamically controlling terahertz wavefronts with cascaded metasurfaces (2021, positive): “…found in the microwave regime (e.g., PIN diodes and varactors), which have been successfully used to construct active metadevices for beam-steering, 34 – 36 programmable holograms, 37,38 and dynamic imaging, 39,40 they are difficult to realize at frequencies higher than THz, due to both size…”
Intelligent Metasurfaces with Continuously Tunable Local Surface Impedance for Multiple Reconfigurable Functions (2018, background): “Moreover, with arbitrary space and time modulation of the loads, our intelligent metasurface can open new opportunities for electromagnetic wave manipulation [45,46].”
Beamforming Optimization for Wireless Network Aided by Intelligent Reflecting Surface With Discrete Phase Shifts (2019, methodology): “Moreover, the switching frequency of the PIN diode can be up to 5 MHz [31], which makes the switching time negligible as compared to the typical wireless channel coherence time.”
Intelligent Reflecting Surface-Aided Wireless Communications: A Tutorial (2020, background): “According to [52], the PIN diode switching frequency can be up to 5 megahertz (MHz), which corresponds to the switching time of 0.2 microsecond ( μ s).”