Real-time terahertz meta-cryptography using polarization-multiplexed graphene-based computer-generated holograms

Rajabalipanah, Hamid; Rouhi, Kasra; Abdolali, Ali; Iqbal, Shahid; Zhang, Lei; Liu, Shuo

doi:10.1515/nanoph-2020-0110

Cited by 47 publications

(19 citation statements)

References 96 publications

(119 reference statements)

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“…The other important issue related to the finding of optimal ways to minimize a coherent source and a camera (without lenses) in the set-up as it was considered in THz imaging [271] and extend it to THz holography. One can expect a new breakthrough relying on the polarization multiplicity and rewritability of a computer-generated metahologram in THz range to host unique merits for exploring real-time metasurface-based cryptography [272].…”

Section: Thz Computational Imagingmentioning

confidence: 99%

Roadmap of Terahertz Imaging 2021

Valušis

Lisauskas

Yuan

et al. 2021

Sensors

175

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In this roadmap article, we have focused on the most recent advances in terahertz (THz) imaging with particular attention paid to the optimization and miniaturization of the THz imaging systems. Such systems entail enhanced functionality, reduced power consumption, and increased convenience, thus being geared toward the implementation of THz imaging systems in real operational conditions. The article will touch upon the advanced solid-state-based THz imaging systems, including room temperature THz sensors and arrays, as well as their on-chip integration with diffractive THz optical components. We will cover the current-state of compact room temperature THz emission sources, both optolectronic and electrically driven; particular emphasis is attributed to the beam-forming role in THz imaging, THz holography and spatial filtering, THz nano-imaging, and computational imaging. A number of advanced THz techniques, such as light-field THz imaging, homodyne spectroscopy, and phase sensitive spectrometry, THz modulated continuous wave imaging, room temperature THz frequency combs, and passive THz imaging, as well as the use of artificial intelligence in THz data processing and optics development, will be reviewed. This roadmap presents a structured snapshot of current advances in THz imaging as of 2021 and provides an opinion on contemporary scientific and technological challenges in this field, as well as extrapolations of possible further evolution in THz imaging.

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Section: Thz Computational Imagingmentioning

confidence: 99%

Roadmap of Terahertz Imaging 2021

Valušis

Lisauskas

Yuan

et al. 2021

Sensors

175

View full text Add to dashboard Cite

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“…All of the required DC voltages fall below the breakdown voltage, computed as 65 V by the I-V curve analysis presented in [42]. This breakdown voltage is corresponding to the breakdown field of 1 V/nm [43]. In addition, the required external voltage for biasing graphene layers related to the values employed in this paper is calculated and presented in Appendix B.…”

Section: Biasing Voltage Calculationmentioning

confidence: 99%

Multi-Channel Near-Field Terahertz Communications Using Reprogrammable Graphene-Based Digital Metasurface

Rouhi

Hosseininejad

Abadal

et al. 2021

J. Lightwave Technol.

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Digital metasurfaces have opened unprecedented ways to accomplish novel electromagnetic devices thanks to their simple manipulation of electromagnetic waves. However, the metasurfaces leveraging phase-only or amplitude-only modulation restricted the full-functionality control of the devices. Herein, a digital graphene-based metasurfaces engineering wavefront amplitude and phase are proposed for the first time to tackle this challenge in the terahertz (THz) band. The concept and its significance are verified using reprogrammable multi-focal metalens based on a 2/2-bit digital unit cell with independent control of 2-bit states of amplitude and phase individually. Moreover, we introduce a novel method to directly transmit digital information over multiple channels via the reprogrammable digital metasurface. Since these metasurfaces are composed of digital building blocks, the digital information can be directly modulated to the metasurface by selecting specific digital sequences and sent them to predetermined receivers distributed in the focal points. Following that, a multi-channel THz high-speed communication system and its application to build three-dimensional wireless agile interconnection are demonstrated. The presented method provides a new architecture for wireless communications without using complicated components of conventional systems. This work motivates versatile meta-devices in many applications envisioned for the THz frequencies, which will play a vital role in modern communications.

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“…Finally, after removing the voltage the, value of σ g remains constant, and no voltage is needed to sustain σ g . Hence, the floating-gate tuning design is preferred to the capacitor-based tuning methods, where the static power consumption is inevitable 63,64 .…”

Section: /28mentioning

confidence: 99%

Switchable and Simultaneous Spatiotemporal Analog Computing

Momeni,

Rouhi,

Fleury

2021

Preprint

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Optical wave-based computing has enabled the realization of real-time information processing in both space and time domains. In the past few years, analog computing has experienced rapid development but mostly for a single function. Motivated by parallel space-time computing and miniaturization, we show that reconfigurable graphene-based metasurfaces offer a promising path towards spatiotemporal computing with integrated functionalities by properly engineering both spatial-and temporal-frequency responses. This paper employs tunable graphene-based metasurface to enable analog signal and image processing in both space and time by tuning the electrostatic bias. In the first part of the paper, we propose a switchable analog computing paradigm in which the proposed metasurface can switch among defined performances by selecting a proper external voltage for graphene monolayers. Spatial isotropic differentiation and edge detection in the spatial channel and first-order temporal differentiation and metasurface-based phaser with linear group-delay response in the temporal channel are demonstrated.In the second section of the paper, simultaneous and parallel spatiotemporal analog computing is demonstrated. The proposed metasurface processor has almost no static power consumption due to its floating-gate configuration. The spatial-and temporal-frequency transfer functions (TFs) are engineered by using a transmission line (TL) model, and the obtained results are validated with full-wave simulations.Our proposal will enable real-time parallel spatiotemporal analog signal and image processing.

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Real-time terahertz meta-cryptography using polarization-multiplexed graphene-based computer-generated holograms

Cited by 47 publications

References 96 publications

Roadmap of Terahertz Imaging 2021

Roadmap of Terahertz Imaging 2021

Multi-Channel Near-Field Terahertz Communications Using Reprogrammable Graphene-Based Digital Metasurface

Switchable and Simultaneous Spatiotemporal Analog Computing

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