Asynchronous Space‐Time‐Coding Digital Metasurface

Wang, Si Ran; Chen, Ming Zheng; Ke, Jun Chen; Cheng, Qiang; Cui, Tiejun

doi:10.1002/advs.202200106

Cited by 36 publications

(13 citation statements)

References 42 publications

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“…However, all the above studies on space-time programmable metamaterials are carried out in a synchronous framework, that is, all the meta-atoms on the aperture share the same modulation frequency. Hence, an asynchronous space-time programmable metamaterial is proposed, where the metaatoms are manipulated by different time coding periods (Wang et al, (2022b)). It is shown that when the metamaterial is operated under asynchronous conditions (all meta-atoms no longer share the same manipulating frequency), the reflected waves will generate dynamic scattered wavefronts in space due to the scattering echoes of each element.…”

Section: Asynchronous Space-time Programmable Metamaterialsmentioning

confidence: 99%

“…It is shown that when the metamaterial is operated under asynchronous conditions (all meta-atoms no longer share the same manipulating frequency), the reflected waves will generate dynamic scattered wavefronts in space due to the scattering echoes of each element. Therefore, the phase gradient between the Wang et al, (2022b). meta-atoms is no longer constant with time, resulting in the time-varying characteristics of the scattered EM waves.…”

Section: Asynchronous Space-time Programmable Metamaterialsmentioning

confidence: 99%

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Programmable metamaterials

et al. 2023

Program. mater.

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As a major approach for controlling electromagnetic (EM) waves, metamaterials have experienced an abundant and rapid development in the 21st century. They have provided flexible and powerful techniques for controlling EM waves and brought many unique applications that are difficult to realise with natural materials. With increasing demands on dynamic controls of the EM waves, many innovations have been conducted in both three-dimensional metamaterials and two-dimensional metasurfaces, in which the meta-atom has been gradually evolved from passive to active. In 2014, coding and digital mechanisms were initially introduced to the metamaterials, further advancing the appearance of digitally programmable metamaterials. The programmable metamaterials have shown great potentials in not only real-time manipulations of the EM waves, but also direct information processing on the EM wave level. In this article, we present an in-depth review of the programmable EM metamaterials and metasurfaces, focusing on the programmable features including theoretical concepts, implementing methods and applications in EM controls. We first give a short retrospect of traditional metamaterials and metasurfaces, followed by the concepts and detailed discussions of digital coding and field-programmable metamaterials. Then, we introduce space-domain, time-domain and space–time-domain programmable metamaterials and metasurfaces, mainly focusing on their theories, functionalities, experimental implementations, and system-level applications. Finally, we conclude the current advances of the programmable metamaterials and metasurfaces, and give a prospect for the future developments.

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Section: Asynchronous Space-time Programmable Metamaterialsmentioning

confidence: 99%

Section: Asynchronous Space-time Programmable Metamaterialsmentioning

confidence: 99%

Programmable metamaterials

et al. 2023

Program. mater.

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“…In fact, such an approach can be feasible and generalized through a space-time-coding digital metasurface with field-programmable-gate-array (FPGA) technology, particularly in the microwave regime 29 – 37 In such a case, different metasurface responses can be digitized by controlling the bias voltages with the adoption of FPGA, which offers the metasurface powerful programmability for space-time modulation.…”

Section: Introductionmentioning

confidence: 99%

Generation of time-varying orbital angular momentum beams with space-time-coding digital metasurface

Zhang

Cheung

et al. 2023

Adv. Photon.

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The recently proposed extreme-ultraviolet beams with time-varying orbital angular momentum (OAM) realized by high-harmonic generation provide extraordinary tools for quantum excitation control and particle manipulation. However, such an approach is not easily scalable to other frequency regimes. We design a space-time-coding digital metasurface operating in the microwave regime to experimentally generate time-varying OAM beams. Due to the flexible programmability of the metasurface, a higher-order twist in the envelope wavefront structure of time-varying OAM beams can be further designed as an additional degree of freedom. The time-varying OAM field patterns are dynamically mapped by developing a two-probe measurement technique. Our approach in combining the programmability of space-time-coding digital metasurfaces and the two-probe measurement technique provides a versatile platform for generating and observing time-varying OAM and other spatiotemporal excitations in general. The proposed time-varying OAM beams have application potentials in particle manipulation, time-division multiplexing, and information encryption.

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“…The phases and/or amplitudes of the STC digital metasurfaces are encoded both in space and time so as to simultaneously manipulate the propagation direction (space domain) and harmonic distribution (frequency domain) of EM waves. STC digital metasurfaces have been applied in many exciting areas such as reciprocal reflection [37], harmonic beam steering [35,38], scattering suppression [35,39], joint multi-harmonic control [40], polarization syntheses [41], analog signal processing [42], direction finding [43], nonuniform periodic modulation [44], multiplexed wireless communication [45].…”

Section: Introductionmentioning

confidence: 99%

Joint time-frequency analysis on space-time-coding digital metasurfaces

et al. 2022

Self Cite

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Space-time and time-varying metastructures have attracted a lot of research interest in recent years. On the other hand, digital programmable metasurfaces have also gained great attention owing to their powerful capabilities in controlling electromagnetic (EM) fields and waves in real time, which is very suitable for implementing spatiotemporal modulations in a digital manner. Accordingly, space-time-coding (STC) digital metasurfaces have recently been proposed to realize advanced manipulations of EM wavefronts and digital information, allowing simultaneous control of propagation directions in the space domain and harmonic distributions in the frequency domain. However, their instantaneous responses and the connection between the time- and frequency-domain characteristics have not yet been fully revealed. Here, we present a joint time-frequency analysis method to revisit STC digital metasurfaces, in which the time-domain instantaneous scattering patterns and frequency-domain equivalent excitations are investigated to analyze the spatial-spectral distributions of the modulated waves. This joint time-frequency analysis method helps to better explain the basic working principle of STC digital metasurfaces and is expected to facilitate more applications in wireless communications, radar, imaging, and beamforming.

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Asynchronous Space‐Time‐Coding Digital Metasurface

Cited by 36 publications

References 42 publications

Programmable metamaterials

Programmable metamaterials

Generation of time-varying orbital angular momentum beams with space-time-coding digital metasurface

Joint time-frequency analysis on space-time-coding digital metasurfaces

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