Article
Engineering, Electrical & Electronic
Goran Isic, Dimitrios C. Zografopoulos, Danka B. Stojanovic, Borislav Vasic, Milivoj R. Belic
Summary: In this study, a theoretical model is proposed for evaluating the diffraction efficiency of an array of lossy resonant elements. The model is demonstrated on an electrically tunable liquid-crystal terahertz beam steering metasurface, and benchmarked against rigorous metasurface simulations.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Feng Zhao, Jiashuai Xu, Zhengyong Song
Summary: This paper utilizes graphene-based Pancharatnam-Berry metasurfaces to achieve beam steering in the terahertz band, designing metasurfaces that can generate multiple beams in space.
IEEE PHOTONICS JOURNAL
(2022)
Article
Materials Science, Multidisciplinary
Fengyuan Yang, Thomas Caiwei Tan, Saurav Prakash, Abhishek Kumar, Ariando Ariando, Ranjan Singh, Nan Wang, Prakash Pitchappa
Summary: This article presents a solution for dynamic beam steering of terahertz waves in 6G networks using spatially-selective vanadium dioxide (VO2) patches and coding metasurfaces. The reversible and abrupt insulator-to-metal phase transition property of VO2 is exploited to achieve a reconfigurable transmission angle for terahertz waves. By designing metasurfaces with specific linear phase gradients and designer phase sequencing, electrically switchable beam steering is achieved. Further development of this concept will enable individual control of each active element, providing a complete 6G RIS solution for 3D terahertz beam manipulation.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Optics
Haifeng Xu, Jierong Cheng, Yunyun Ji, Fei Fan, Shengjiang Chang
Summary: Describes a metasurface that uses local phase modulation in subwavelength unit cells for wavefront shaping. Multiple beams are assigned to different diffraction orders located coaxially along the same direction, with their wavefronts tailored by optimizing the diffraction coefficients in two orders and two polarization states of a supercell. By evenly splitting the energy into two orders and adjusting the zeroth-order diffraction phase, a Bessel beam and a vortex beam are simultaneously generated in the near field and far field along a coaxial direction.
Article
Engineering, Electrical & Electronic
Jiashuai Xu, Wenwen Liu, Zhengyong Song
Summary: This paper presents a graphene-based coding metasurface for dynamic beam steering of terahertz waves, demonstrating its versatility in dynamically controlling electromagnetic waves. Experimental results verify the dynamic tunability of the proposed metasurface for various functionalities, showcasing its potential in terahertz wave applications.
IEEE PHOTONICS JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Yaseman Shiri, Hichem Guerboukha, Daniel M. M. Mittleman
Summary: Considerable research interest has been focused on the possibility of manipulating terahertz wavefronts using metasurfaces. Metasurfaces enable targeted beam direction through strategic placement of meta-elements. With rapid prototyping techniques, metasurfaces can be fabricated quickly and inexpensively, even on flexible substrates. In this study, we experimentally and numerically analyze the performance of a terahertz metasurface printed on paper under various curvature conditions. Our findings show minimal impact on the refracted beam direction and similar performance when the metasurface is bent, simplifying the design and modeling criteria for conformable metasurfaces.
JOURNAL OF INFRARED MILLIMETER AND TERAHERTZ WAVES
(2023)
Article
Chemistry, Multidisciplinary
Lingyun Zhang, Li Zhang, Rongbo Xie, Yibo Ni, Xiaoyu Wu, Yuanmu Yang, Fei Xing, Xiaoguang Zhao, Zheng You
Summary: Cascaded metasurfaces exhibit dynamic light manipulation by mechanically tuning far-field interactions. A design paradigm using a ray-tracing scheme is proposed to operate cascaded metasurfaces optimally at achievable gap sizes. A continuous 2D beam-steering device for 1064 nm light is designed as proof of concept, showing a tuning range of +/- 45 degrees within +/- 3.5 mm biaxial translations while maintaining low divergence. The generalized design paradigm can enable tunable cascaded metasurface devices for various applications.
Review
Engineering, Electrical & Electronic
Yasuaki Monnai, Xuyang Lu, Kaushik Sengupta
Summary: Free-space transmission of THz waves provides great opportunities for wireless applications in the 6G era and beyond. While THz waves enhance information capacity and spatial resolution, they also suffer from severe path loss. Beam steering, implemented through active/passive phased arrays or diffractive/frequency dispersive structures, is crucial for compensating path loss. Application-driven system design approaches, coupled with signal processing, have emerged to overcome hardware limitations.
JOURNAL OF INFRARED MILLIMETER AND TERAHERTZ WAVES
(2023)
Article
Nanoscience & Nanotechnology
Qingqing Cheng, Juncheng Wang, Ling Ma, Zhixiong Shen, Jing Zhang, Xiaoying Zheng, Tao Chen, Ye Yu, Dong Yu, Qiong He, Wei Hu, Tao Li, Songlin Zhuang, Lei Zhou
Summary: By designing and fabricating an achromatic Airy-beam metalens, achromatic Airy beams with autofocusing and self-healing properties are successfully demonstrated, with a larger depth of focus. This paves the way for flat photonic devices for noninvasive biomedical imaging and light-sheet microscopy applications, with a numerical demonstration of a device protocol provided.
Article
Materials Science, Multidisciplinary
Jierong Cheng, Xipu Dong, Sai Chen, Yiwu Yuan, Qiye Wen, Shengjiang Chang
Summary: This study proposes an accordion-shaped single-element metagratings for THz beam scanning and angle-adaptive retroreflection. Dynamic beam steering is achieved through mechanical compression and rotation, allowing for beam scanning in a plane and over the 3D space. The study also investigates an angle-adaptive retroreflector with near perfect diffraction efficiency.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Chemistry, Analytical
Bin Zheng, Xin Rao, Yuyu Shan, Chuandong Yu, Jingke Zhang, Na Li
Summary: This paper proposes a method for reconfigurable antennas using graphene-based coding metasurfaces and designs and simulates various coding sequences for different applications.
Article
Engineering, Mechanical
Xiao-Shuang Li, Yan-Feng Wang, Yue-Sheng Wang
Summary: In this study, a sparse binary elastic metasurface (SBEMs) is designed to regulate flexural waves, and its effectiveness and enhanced energy output capability are demonstrated through experiments. This design strategy provides a new approach for tailoring flexural waves.
EXTREME MECHANICS LETTERS
(2022)
Article
Optics
Veysel Ercaglar, Hodjat Hajian, Andriy E. Serebryannikov, Ekmel Ozbay
Summary: The proposed multifunctional gradient metasurfaces, composed of binary Si microcylinders integrated with VO2 and graphene, can advance THz science and technology by providing tunable features. These metasurfaces act as transmittive or reflective beamsplitters for VO2 and can be used in THz interferometers, multiplexers, and light absorbers.
Article
Materials Science, Multidisciplinary
Muhammad Shemyal Nisar, Shahid Iqbal, Sai-Wai Wong
Summary: Coding metasurfaces have been widely used in free space optics but not integrated photonic applications due to the lack of implementation methods. The use of low-loss phase change materials like Sb2S3 has made it possible to implement reprogrammable integrated metasurfaces. This paper presents Sb2S3 based 1-bit and 2-bit coding metasurfaces that can potentially be practically implemented and achieve functionalities such as beam focusing, beam splitting, and beam steering. This has potential applications in various fields including integrated photonic computational platforms.
RESULTS IN PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Haonan Chang, Zhenyao Li, Wenkai Lou, Qifeng Yao, Jia-Min Lai, Bing Liu, Haiqiao Ni, Zhichuan Niu, Kai Chang, Jun Zhang
Summary: Researchers have designed a THz mechanical frequency semiconductor pillar microcavity optomechanical device based on a GaAs/AlAs nanophononic superlattice, by introducing acoustic topological interface states. The device enables the quantum ground state to be reached at high temperatures, and achieves frequency matching between optical cavity modes, providing potential for laser cooling and low threshold phonon lasing.
Article
Engineering, Electrical & Electronic
Dimitrios Chatzidimitriou, Dimitrios C. Zografopoulos, Emmanouil E. Kriezis
Summary: This study demonstrates the theoretical application of graphene saturable absorption for saturable absorption mirrors based on planar silicon photonic Bragg gratings. Two geometries, silicon wire grating and silicon slot grating, were investigated to showcase the enhanced interaction between light and matter in high-confinement slot waveguides. The effects of other nonlinear properties, such as silicon's Kerr effect and two photon absorption, were also considered but were shown to have a negligible impact compared to graphene's saturable absorption.
IEEE PHOTONICS JOURNAL
(2022)
Article
Multidisciplinary Sciences
D. C. Zografopoulos, J. F. Algorri, J. M. Lopez-Higuera, H. E. Hernandez-Figueroa, V Dmitriev
Summary: This study investigates quasi-dark resonances with antiferromagnetic order in a near-infrared metasurface. By reducing the symmetry of the metasurface, access to the quasi-dark mode is achieved. The study reveals the key optical properties of the quasi-dark mode, including resonant wavelengths, quality factors, and angular dispersion. The thickness of the silicon metasurface and the angle of incidence can be used to adjust the asymmetry degree and resonant wavelength of the mode.
SCIENTIFIC REPORTS
(2022)
Review
Materials Science, Multidisciplinary
Rafal Kowerdziej, Antonio Ferraro, Dimitrios C. Zografopoulos, Roberto Caputo
Summary: This article reviews recent progress in active metamaterials, focusing on hybrid composites that combine plasmonic and dielectric materials with soft matter assemblies. Theoretical background, experimental realizations, and state-of-the-art applications in light-matter interactions are discussed, and current challenges in the field are addressed.
ADVANCED OPTICAL MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Daniele Pirrone, Antonio Ferraro, Dimitrios C. Zografopoulos, Walter Fuscaldo, Pascal Szriftgiser, Guillaume Ducournau, Romeo Beccherelli
Summary: We demonstrate the effectiveness of frequency selective surface filters in wireless communications at low terahertz (THz) frequencies. The filters have been shown to have minimal impact on signals while effectively rejecting interfering signals, making them a promising solution for efficient spectrum management in future 6G wireless applications.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Correction
Multidisciplinary Sciences
N. Bennis, T. Jankowski, O. Strzezysz, A. Pakula, D. C. Zografopoulos, P. Perkowski, J. M. Sanchez-Pena, J. M. Lopez-Higuera, J. F. Algorri
SCIENTIFIC REPORTS
(2022)
Article
Multidisciplinary Sciences
N. Bennis, T. Jankowski, O. Strzezysz, A. Pakua, D. C. Zografopoulos, P. Perkowski, J. M. Sanchez-Pena, J. M. Lopez-Higuera, J. F. Algorri
Summary: This work presents the application of an experimental nematic liquid crystal (LC) mixture in a large aperture lens. The LC material, composed of terphenyl and biphenyl derivatives compounds, exhibits high birefringence and low viscosity. The excellent properties of this LC mixture make it of interest for lenses and optical devices in both visible and infrared regions.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Multidisciplinary
Walter Fuscaldo, Francesco Maita, Luca Maiolo, Romeo Beccherelli, Dimitrios C. Zografopoulos
Summary: In this study, the dielectric properties of three commercially available high-permittivity Rogers laminates were characterized in the sub-terahertz range using terahertz time-domain spectroscopy measurements. A transmission-line model was developed to obtain reflectance spectra by fitting the frequency-dispersive complex relative permittivity of the substrates. The results showed that the thermoset microwave laminate TMM10i exhibited lower frequency dispersion and overall dielectric losses, making it a promising candidate for low-profile and broadband components in novel terahertz applications.
APPLIED SCIENCES-BASEL
(2022)
Article
Multidisciplinary Sciences
Victor Dmitriev, Dimitrios C. C. Zografopoulos, Luis P. V. Matos
Summary: We discuss a method based on magnetic group theory for analyzing symmetric electromagnetic components with magnetic media. In this method, some of the irreducible corepresentations take on complex values exp(i theta), where theta is a real parameter. We provide a possible physical interpretation for this parameter. The symmetry-adapted linear combination method combined with the corepresentation theory is applied to the problem of current modes in an array of magnetized graphene elements. Numerical simulations and analyses are presented for the scattering matrix and eigensolutions of the array, as well as an example of a waveguide with a specific type of degeneracy described by symmetry C(4)v(C(2)v).
Article
Optics
J. F. Algorri, F. Dell'Olio, Y. Ding, F. Labbe, V. Dmitriev, J. M. Lopez-Higuera, J. M. Sanchez-Pena, L. C. Andreani, M. Galli, D. C. Zografopoulos
Summary: We investigate a metasurface supporting a silicon-slot quasi-bound state in the continuum (qBIC) mode resonating in the near-infrared spectrum both theoretically and experimentally. The metasurface is composed of circular slots etched in a silicon layer on a sapphire substrate. By reducing the symmetry of the metasurface unit cell, we access the symmetry-protected mode and analyze its properties through finite-element full-wave and eigenfrequency analysis. The measured transmittance spectra confirm the excitation of the investigated qBIC mode with experimental quality factors exceeding 700. The resonant qBIC mode exhibits strong field confinement in the slots, leading to high sensitivity values for refractometry.
OPTICS AND LASER TECHNOLOGY
(2023)
Article
Chemistry, Analytical
Odysseas Tsilipakos, Zacharias Viskadourakis, Anna C. Tasolamprou, Dimitrios C. Zografopoulos, Maria Kafesaki, George Kenanakis, Eleftherios N. Economou
Summary: A conductive meta-atom of toroidal topology is studied for its sharp and highly controllable resonant response. The structure is fabricated with 3D printing and coated with silver paste, resulting in a practical and potentially low-loss system. Measurements show good agreement with simulations in the 5 GHz regime.
Article
Chemistry, Multidisciplinary
Jose Francisco Algorri, Victor Dmitriev, Jose Miguel Lopez-Higuera, Dimitrios C. Zografopoulos
Summary: This study proposes a novel dielectric metasurface that addresses the two main problems in sensing and spectroscopy based on electromagnetic field enhancement. By supporting delocalized modes and quasi-bound states in the continuum, the metasurface achieves polarization-insensitive, high-Q-factor resonances with very high electric field enhancements. This work opens up new research opportunities in optical sensing and advanced spectroscopy.
Article
Computer Science, Information Systems
Walter Fuscaldo, Elahehsadat Torabi, Dimitrios C. Zografopoulos, Danilo Erricolo, Romeo Beccherelli
Summary: This paper proposes a rectangular metallic leaky waveguide antenna loaded with liquid crystals to mitigate the trade-off between directivity and tunable angular range in dynamic beamscanning antennas. The antenna design is optimized to achieve a tunable angular range of 28 degrees while maintaining a gain of 7 dBi. Rigorous modeling and full-wave simulations validate the antenna's performance.
Review
Materials Science, Multidisciplinary
Dimitrios C. Zografopoulos, Odysseas Tsilipakos
Summary: All-dielectric metasurfaces have been extensively studied as a flat-optics platform for advanced manipulation of electromagnetic waves. They can be engineered to have either extremely narrowband response or ultrabroadband response, opening the path towards enhanced light-matter interaction and strong field enhancement, or achromatic, flat components for imaging and ultra-short pulse processing applications.
MATERIALS ADVANCES
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Daniele Pirrone, Antonio Ferraro, Dimitrios C. Zografopoulos, Pascal Szriftgiser, Guillaume Ducournau, Romeo Beccherelli, Walter Fuscaldo
Summary: This research experimentally demonstrates the capabilities of frequency-selective surface (FSS) as free-space filters for wireless communications in the 300 GHz band. The presence of a filter plays a key role in protecting wireless communications from out-of-band interference without using computation intensive forward error correction schemes.
PROCEEDINGS OF THE 2022 21ST MEDITERRANEAN MICROWAVE SYMPOSIUM (MMS 2022)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Francesca Imperato, P. Burghignoli, Dimitrios C. Zografopoulos, Romeo Beccherelli, Alessandro Galli, Walter Fuscaldo
Summary: A one-dimensional leaky-wave antenna based on nematic liquid crystals (NLC) is proposed in this work for dynamic beam-steering of the antenna radiation pattern at a fixed frequency, with full-wave results provided to demonstrate the concept.
PROCEEDINGS OF THE 2022 21ST MEDITERRANEAN MICROWAVE SYMPOSIUM (MMS 2022)
(2022)