Spread-Spectrum Selective Camouflaging Based on Time-Modulated Metasurface

Wang, Xiaoyi; Caloz, Christophe

doi:10.1109/tap.2020.3008621

Cited by 86 publications

(41 citation statements)

References 37 publications

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“…Generally, with the aid of the STC strategy, the scattered energy can be excellently suppressed in both the spatial and spectral domains, which ensures a more effective and robust effect of RCS reduction. Other related applications of scattering control also include spectral camouflage by introducing random time-modulated signals [ 116 ].…”

Section: Recent Advances and Representative Applicationsmentioning

confidence: 99%

“…That is to say, one can simultaneously manipulate the harmonic distribution and propagation direction of reflected waves [ 110 ]. The STC digital metasurfaces extend and generalize the concepts of “phase-switched screens” [ 111 ] and “time-modulated arrays” [ 112 ] and have been applied successfully to harmonic beam control [ 110 ], scattering reduction [ 110 ], nonreciprocal effect [ 113 ], multibit phase generation [ 114 ], terahertz harmonic manipulations [ 115 ], spread-spectrum camouflaging [ 116 ], analog computing [ 117 ], and wireless communications [ 118 ].…”

Section: Introductionmentioning

confidence: 99%

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Space-Time-Coding Digital Metasurfaces: Principles and Applications

Zhang

Cui

2021

Research

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Space-time-modulated metastructures characterized by spatiotemporally varying properties have recently attracted great interest and become one of the most fascinating and promising research fields. In the meantime, space-time-coding digital metasurfaces with inherently programmable natures emerge as powerful and versatile platforms for implementing the spatiotemporal modulations, which have been successfully realized and used to manipulate the electromagnetic waves in both the spectral and spatial domains. In this article, we systematically introduce the general concepts and working principles of space-time-coding digital metasurfaces and provide a comprehensive survey of recent advances and representative applications in this field. Specifically, we illustrate the examples of complicated wave manipulations, including harmonic beam control and programmable nonreciprocal effect. The fascinating strategy of space-time-coding opens the door to exciting scenarios for information systems, with abundant applications ranging from wireless communications to imaging and radars. We summarize this review by presenting the perspectives on the existing challenges and future directions in this fast-growing research field.

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Section: Recent Advances and Representative Applicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Space-Time-Coding Digital Metasurfaces: Principles and Applications

Zhang

Cui

2021

Research

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“…Space-time coding has also been recently adopted to develop digital metasurfaces capable of light manipulation in space and frequency while offering nonreciprocity [56][57][58][59]. In addition to nonreciprocity, TMMs hold a great potential for a wide range of applications such as wavefront engineering [60][61][62][63], extreme energy accumulation [64], spectral camouflaging [65,66], wide band impedance matching [67,68], signal amplification [69], pulse shaping [70][71][72], and providing multiple access through multiplexing and multicasting [73,74]. A fundamental property of a TMM is frequency mixing which leads to conversion of an incident frequency (f 0 ) into higher-order frequency harmonics.…”

Section: Introductionmentioning

confidence: 99%

Time-varying optical vortices enabled by time-modulated metasurfaces

2020

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AbstractIn this paper, generation of optical vortices with time-varying orbital angular momentum (OAM) and topological charge is theoretically demonstrated based on time-modulated metasurfaces with a linearly azimuthal frequency gradient. The topological charge of such dynamic structured light beams is shown to continuously and periodically change with time evolution while possessing a linear dependence on time and azimuthal frequency offset. The temporal variation of OAM yields a self-torqued beam exhibiting a continuous angular acceleration of light. The phenomenon is attributed to the azimuthal phase gradient in space-time generated by virtue of the spatiotemporal coherent path in the interference between different frequencies. In order to numerically authenticate this newly introduced concept, a reflective dielectric metasurface is modelled consisting of silicon nanodisk heterostructures integrated with indium-tin-oxide and gate dielectric layers on top of a mirror-backed silicon slab which renders an electrically tunable guided mode resonance mirror in near-infrared regime. The metasurface is divided into several azimuthal sections wherein nanodisk heterostructures are interconnected via nanobars serving as biasing lines. Addressing azimuthal sections with radio-frequency biasing signals of different frequencies, the direct dynamic photonic transitions of leaky-guided modes are leveraged for realization of an azimuthal frequency gradient in the optical field. Generation of dynamic twisted light beams with time-varying OAM by the metasurface is verified via performing several numerical simulations. Moreover, the role of modulation waveform and frequency gradient on the temporal evolution and diversity of generated optical vortices is investigated which offer a robust electrical control over the number of dynamic beams and their degree of self-torque. Our results point toward a new class of structured light for time-division multiple access in optical and quantum communication systems as well as unprecedented optomechanical manipulation of objects.

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“…More recently, time-modulated metasurfaces (TMMs) have emerged as a new class of active metasurfaces in which the external stimuli controlling the optical properties of the metasurface are varying periodically in time [40], [48]- [50]. These metasurfaces have been shown to enable a wide range of novel physical phenomena including nonreciprocity [51]- [59], wavefront engineering [60]- [64], spatiotemporal light manipulation [65]- [67], signal amplification [68], [69], extreme energy accumulation [70], wideband impedance matching [71], pulse shaping and reversal [72]- [74], and camouflaging [75], [76]. A fundamental property of such metasurfaces is the frequency mixing functionality which leads to generation of higher-order frequency harmonics.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Multichannel Terahertz Communication by Space-Time Shared Aperture Metasurfaces

2020

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We propose a technique for adaptive multichannel communication in the low-terahertz frequency regime through simultaneous and independent multifrequency multibeam scanning via a single time-modulated metasurface consisting of graphene micro-patch antennas whose Fermi energy levels are modulated by radio-frequency biasing signals. For this purpose, we divide the metasurface aperture into interleaved orthogonally modulated sub-array antennas with distinct modulation frequencies, rendering a shared aperture in space-time. The higher-order frequency harmonics generated by the sub-arrays in such a space-time shared-aperture metasurface are mutually orthogonal as they do not yield an observable interference pattern. A distinct constant progressive modulation phase delay can be adopted in each sub-array to independently scan its corresponding higher-order frequency harmonics via dispersionless modulationinduced phase gradient with minimal sidelobe level and full angle-of-view over a wide bandwidth. The number of sub-arrays and distinct channels can be scaled easily without suffering from cross-talk due to orthogonality of the channels. The concept is established theoretically and verified through numerical simulations. We characterize active beam-scanning performance of the space-time shared aperture metasurface in terms of gain and half power beamwidth and their dependence to the array architecture. We consider both one-dimensional and two-dimensional interleaving for scanning the beams along elevation and azimuth angles. We also obtain the upper bounds for the number of independent channels attainable without compromising angle-of-view as 8 and 64 for one-dimensional and two-dimensional interleaving, respectively within the same physical aperture. Our results point toward high-capacity platforms with low size, weight and power for next generations of terahertz communication systems. INDEX TERMS Time-modulated metasurface, shared-aperture antennas, beam steering, terahertz communication

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Spread-Spectrum Selective Camouflaging Based on Time-Modulated Metasurface

Cited by 86 publications

References 37 publications

Space-Time-Coding Digital Metasurfaces: Principles and Applications

Space-Time-Coding Digital Metasurfaces: Principles and Applications

Time-varying optical vortices enabled by time-modulated metasurfaces

Adaptive Multichannel Terahertz Communication by Space-Time Shared Aperture Metasurfaces

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