Adopting image theorem for rigorous analysis of a perfect electric conductor–backed array of graphene ribbons

Rahmanzadeh, Mahdi; Abdolali, Ali; Khavasi, Amin; Rajabalipanah, Hamid

doi:10.1364/josab.35.001836

Cited by 31 publications

(13 citation statements)

References 33 publications

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“…The arbitrary control of surface electric conductivity of graphene through external biasing or chemical doping has shown a great flexibility in achieving various functionalities. Because of having strong interaction with EM fields, the possibility of exploiting the array of graphene metasurfaces in a wide range of interesting applications from tunable/broadband absorption [49,50] to THz wave tailoring [51] has been conceptually assessed. Despite the rapid progress in high frequency active metasurfaces, the simultaneous realization of real-time reconfigurability, high efficiency, and polarization-multiplexing for realizing THz holograms have remained unsolved.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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AbstractAs one of the cutting-edge technologies in advanced information science, wave-based cryptography is a prerequisite to enable a plethora of secure encrypting platforms which can be realized by smart multiplexing techniques together with suitable metasurface holograms (meta-holograms). Here, relying on the polarization multiplicity and re-writability of a computer-generated meta-hologram, a fully secure communication protocol is elaborately developed at the terahertz spectrum to host unique merits for exploring real-time metasurface-based cryptography (meta-cryptography) where highly restricted access of information is imposed. The proposed meta-cryptography exploits two dynamic near-field channels of a meta-hologram whose information can be instantaneously re-written without any polarization rotation and with high contrast and acceptable frequency bandwidth. The computer-generated meta-hologram is constructed based on the weighted Gerchberg–Saxton algorithm via a two-dimensional array of vertical graphene strips whose anisotropic reflection is merely determined by external biasing conditions. Several illustrative examples have been presented to demonstrate the perfect secrecy and polarization cross-talk of the proposed meta-cryptography. Numerical simulations corroborate well our theoretical predictions. As the first demonstration of dynamic THz meta-cryptography, the meta-hologram information channels can be deciphered into manifold customized messages which would be instrumental in data storage systems offering far higher data rates than electronic encryption can deliver.

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Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Recent years have witnessed a clear tendency toward achieving multiple contour beams using fully planar metasurface‐based devices with a lighter weight and lower cost compared to the solid reflectors [ 6 ] and bulky metamaterials. [ 7 ] Metasurfaces, engineered arrays of artificially patterned microelements on a flat surface, have recently emerged as a flourishing concept which attracts tremendous interest because of providing peculiar routes to manipulate the phase, [ 8–10 ] polarization, [ 11 ] amplitude, [ 12–14 ] transversal shape, [ 15,16 ] and trajectory [ 17–20 ] of the electromagnetic (EM) fields. Since Capasso's group introduced the generalized laws of refraction/reflection in 2011, [ 21 ] this 2D version of metamaterials has inspired many exceptional and modern devices, typically in the field of antennas and antenna accessories.…”

Section: Introductionmentioning

confidence: 99%

Flexible Manipulation of Emitting Beams Using Single‐Aperture Circularly Polarized Digital Metasurface Antennas: Multi‐Beam Radiation toward Vortex‐Beam Generation

Nadi

Rajabalipanah

Cheldavi

et al. 2020

Advcd Theory and Sims

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As the technological demands for multiple‐input multiple‐output communication systems increasingly grow, there is a critical need for the next generation of multi‐beam radiators. The concept of single‐feed compact phase‐encoded metasurface antennas is introduced, the radiation specifications of which can be flexibly manipulated to provide circularly‐polarized single‐, dual‐, quad‐beam far‐field patterns, a circularly‐polarized optical angular momentum‐carrying beam, and a circularly‐polarized quasi‐omnidirectional emission. With a small footprint area at f = 5.8 GHz, the proposed circularly polarized coding metasurface antenna (CPCMA) consists of several radiating meta‐atoms with 2‐bit excitation phases of 0, π/2, π, and 3π/2. Compared with conventional antenna arrays, the center‐to‐center distance of the coding elements is noticeably reduced, where periodic boundary conditions have been employed to analyze the inter‐element coupling effects. A low‐cost and simple corporate feed network is also designed to implement the required coding mask of each CPCMA type. To verify the performance of the proposed CPCMA, a prototype is fabricated and measured. Proof‐of‐concept experiments demonstrate excellent agreement with numerical simulations and theoretical predictions. This constructs a bridge between conventional arrays and digital metasurfaces, providing a powerful host for the next generation of multi‐beam circularly polarized radiators.

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“…In another context, metasurfaces are known as two-dimensional versions of the metamaterial family [23] at subwavelength scales which cover a broad scope of applications due to their strong interactions with light and ease of fabrication [24]. They provide prominent abilities for polarizing [25][26][27][28], absorbing [29][30][31][32], channeling [33][34][35][36][37][38][39][40], and processing [41][42][43][44] waves, especially within optical frequencies. Several analytical frameworks have been recently developed to synthesize metasurfaces at microscopic to macroscopic scales such as impedance/ admittance matrices [45,46], generalized sheet transition conditions (GSTCs) by susceptibility tensors [47,48], polarizability tensors [49][50][51], and local complex scattering parameters [39,[52][53][54].…”

Section: Introductionmentioning

confidence: 99%

Parallel integro-differential equation solving via multi-channel reciprocal bianisotropic metasurface augmented by normal susceptibilities

et al. 2019

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Analog optical signal processing has dramatically transcended the speed and energy limitations accompanied with its digital microelectronic counterparts. Motivated by recent metasurface's evolution, the angular scattering diversity of a reciprocal passive bianisotropic metasurface with normal polarization is utilized in this paper to design a multi-channel meta-computing surface, performing multiple advanced mathematical operations on input fields coming from different directions, simultaneously. Here, the employed ultra-thin bianisotropic metasurface computer is theoretically characterized based on generalized sheet transition conditions and susceptibility tensors. The operators of choice are deliberately dedicated to asymmetric integro-differential equations and image processing functions, like edge detection and blurring. To clarify the concept, we present several illustrative simulations whereby diverse wave-based mathematical functionalities have been simultaneously implemented without any additional Fourier lenses. The performance of the designed metasurface overcomes the nettlesome restrictions imposed by the previous analog computing proposals such as bulky profiles, asserting only single mathematical operation, and most importantly, supporting only the even-symmetric operations for normal incidences. Besides, the realization possibility of the proposed metasurface computer is conceptually investigated via picturing the angular scattering behavior of several candidate meta-atoms. This work opens a new route for designing ultra-thin devices executing parallel and accelerated optical signal/image processing.

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Adopting image theorem for rigorous analysis of a perfect electric conductor–backed array of graphene ribbons

Cited by 31 publications

References 33 publications

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

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

Flexible Manipulation of Emitting Beams Using Single‐Aperture Circularly Polarized Digital Metasurface Antennas: Multi‐Beam Radiation toward Vortex‐Beam Generation

Parallel integro-differential equation solving via multi-channel reciprocal bianisotropic metasurface augmented by normal susceptibilities

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