Article
Optics
Khatereh Moradi, Ali Pourziad, Saeid Nikmehr
Summary: This paper presents a frequency reconfigurable THz antenna using graphene instead of PIN diodes, enabling the antenna to work in different modes by changing graphene parameters. The proposed antenna's operation frequency ranges from 2.8 to 4.2 THz, achieving suitable radiation patterns, wide impedance bandwidth, good impedance matching, and an average gain of 2dB.
Article
Optics
Arun Kumar Varshney, Nagendra P. Pathak, Debabrata Sircar
Summary: This paper proposes a frequency reconfigurable dielectric lens antenna (DLA) to compensate for high attenuation in the THz region caused by atmospheric losses. The DLA is fed using an aperture coupled graphene plasmonic nanoantenna, with frequency tuning achieved by varying the chemical potential of graphene. The proposed DLA exhibits high gain, narrow beamwidth, high radiation efficiency, and stable input impedance.
Article
Engineering, Electrical & Electronic
Khatereh Moradi, Pardis Karimi
Summary: This paper presents a patch antenna with a unique shape and feeding at terahertz frequency. By utilizing the properties of graphene, the shape of the patch can be changed to triangle, rectangle, circle, and slotted patches. By changing the shape of the patch, it is possible to simultaneously utilize the features of patches with different shapes in one antenna structure. In addition to the ability to change the resonance frequency and polarization, the antenna also has improved gain through the use of metasurface and proximity coupled feed.
AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS
(2023)
Article
Optics
Myunghwan Kim, Sangin Kim, Soeun Kim
Summary: A new type of mid-infrared ultra-compact optical modulator composed of a graphene metasurface is proposed in this study. Unlike previous schemes, this modulator utilizes the topological characteristic of the isofrequency contour in the hyperbolic metasurface to modulate transmission, providing a modulation depth of 10.7 dB with a length of 750 nm, which is approximately 1/30 of an operating wavelength.
Article
Nanoscience & Nanotechnology
Juan A. Delgado-Notario, Wojciech Knap, Vito Clerico, Juan Salvador-Sanchez, Jaime Calvo-Gallego, Takashi Taniguchi, Kenji Watanabe, Taiichi Otsuji, Vyacheslav V. Popov, Denis V. Fateev, Enrique Diez, Jesus E. Velazquez-Perez, Yahya M. Meziani
Summary: This study fabricated a graphene terahertz field-effect transistor with an asymmetric-dual-grating-gate and a continuous graphite back-gate, which enhanced the THz rectified signal by forming abrupt junctions with different potential barriers. This paves the way for new record performances of graphene THz nano-photodetectors.
Article
Optics
Yuyu Li, Roberto Paiella
Summary: Graphene plasmonics is used to extend metasurface technology to the terahertz spectral region, providing active tunability. A comprehensive design platform is introduced for the development of THz metasurfaces capable of complex wavefront manipulation functionalities. This approach is compatible with graphene grown by chemical vapor deposition and shows promise for a wide range of THz technologies.
Article
Materials Science, Multidisciplinary
S. Candussio, S. Bernreuter, T. Rockinger, K. Watanabe, T. Taniguchi, J. Eroms, I. A. Dmitriev, D. Weiss, S. D. Ganichev
Summary: This article reports on the observation of circular transversal terahertz photoconductivity in monolayer graphene supplied by a back gate. The photoconductivity response is caused by free carrier absorption and reverses its sign when the radiation helicity is switched. Additionally, the observation of a dc Hall effect suggests the breaking of time inversion symmetry induced by circularly polarized terahertz radiation in the absence of a magnetic field.
Article
Multidisciplinary Sciences
Myunghwan Kim, Seong-Han Kim, Chul Kang, Soeun Kim, Chul-Sik Kee
Summary: Graphene-based optical modulators have been widely studied, but weak graphene-light interactions limit the achievement of high modulation depth with low energy consumption. In this study, a high-performance graphene-based optical modulator, consisting of a photonic crystal structure and a waveguide, is proposed. It exhibits an electromagnetically-induced-transparency-like transmission spectrum at terahertz frequency, enhancing light-graphene interaction. The designed modulator achieves a high modulation depth of 98% with a small Fermi level shift of 0.05 eV, making it suitable for low power consumption in active optical devices.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Physical
Neha Verma, Anil Govindan, Pawan Kumar
Summary: Graphene is a promising material for terahertz radiation generation due to its unique properties, such as tunable surface plasmon resonance through doping. A scheme proposed to excite terahertz graphene plasmons at different frequencies on a graphene sheet involves nonlinear mixing of two laser beams. The amplitude of terahertz graphene surface plasmons decreases monotonically at higher frequencies due to weak coupling.
Article
Optics
Futai Hu, Sai Chen, Rui Wang, Yuan Meng, Qiang Liu, Mali Gong
Summary: In this study, the combination of graphene with a nested cavity has been utilized to achieve optimal gain and terahertz perfect absorption under photoexcitation. Tuning the material conductivity can switch extremums of energy transfer, enhancing the working efficiency. The concept of the nested cavity can be extended to different materials and guided modes, enabling high-contrast dynamic modulation and multifunctional photonic devices.
Article
Multidisciplinary Sciences
Mohamed Mamdouh M. Ali, Shoukry Shams, Mahmoud Elsaadany, Ghyslain Gagnon, Ke Wu
Summary: This paper introduces the use of graphene to implement a reconfigurable printed ridge gap waveguide structure in the terahertz frequency range for the first time. This guiding structure exhibits low loss and is suitable for both millimeter and terahertz wave applications.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Electrical & Electronic
Xin-Lei Lv, Bian Wu, Chi Fan, Tao Su, Dong Jiang
Summary: This paper proposes a frequency and polarization hybrid reconfigurable microstrip antenna utilizing graphene-based tunable resistors. The antenna includes a T-shaped power divider, a 90 degrees phase shifter, and a circular patch. By adjusting the resistance of the graphene nanoplates, the antenna can achieve different polarization modes and manipulation of gain in specific frequency bands.
IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS
(2023)
Article
Optics
Anna Theodosi, Odysseas Tsilipakos, Costas M. Soukoulis, Eleftherios N. Economou, Maria Kafesaki
Summary: Graphene is a promising material for nonlinear applications in the THz regime due to its high third order nonlinearity and ability to support surface plasmons. In this study, 2D-patterned graphene-patch metasurfaces are investigated for efficient third harmonic generation. The efficiency is enhanced by aligning the fundamental and third harmonic frequencies with the metasurface resonances, achieved through 2D-patterning that modifies the dispersion of plasmons. High efficiencies of -20dB (1%) for input intensity 0.1 MW/cm(2) are achieved, and the results demonstrate the potential of graphene-based metasurfaces for nonlinear applications.
Article
Optics
Chengcheng Huang, Yonggang Zhang, Lanju Liang, Haiyun Yao, Fu Qiu, Wenjia Liu
Summary: A novel four-band tunable absorber sensor based on graphene is proposed, with the ability to directly control resonant frequencies and achieve absorption rates higher than 99% by adjusting the Fermi level of graphene. The sensor exhibits superior refractive index sensitivity and good linearity, making it highly promising for applications in the biomedical field.
Article
Multidisciplinary Sciences
Mohammad Mashayekhi, Pooria Kabiri, Amir Saman Nooramin, Mohammad Soleimani
Summary: This article investigates the design of a reconfigurable multi-band patch antenna based on graphene for terahertz applications. The study evaluates the dependence of the antenna radiation characteristics on its geometric parameters and graphene properties, and explores the use of a deep neural network to predict antenna parameters. The results show high accuracy and negligible errors, highlighting the potential applications of the proposed antenna in the THz frequency band.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Multidisciplinary
Nikita Nefedkin, Ahmed Mekawy, Jonas Krakofsky, Yongrui Wang, Alexey Belyanin, Mikhail Belkin, Andrea Alu
Summary: Engineered intersubband transitions in multi-quantum well semiconductor heterostructures exhibit high second-order nonlinear susceptibilities in metasurfaces. By optimizing the design, the saturation limits in mid-infrared frequency upconversion in nonlinear metasurfaces are significantly extended. This has important implications for night-vision imaging and compact nonlinear wave mixing systems.
ADVANCED MATERIALS
(2023)
Review
Optics
Hannah Price, Yidong Chong, Alexander Khanikaev, Henning Schomerus, Lukas J. Maczewsky, Mark Kremer, Matthias Heinrich, Alexander Szameit, Oded Zilberberg, Yihao Yang, Baile Zhang, Andrea Alu, Ronny Thomale, Iacopo Carusotto, Philippe St-Jean, Alberto Amo, Avik Dutt, Luqi Yuan, Shanhui Fan, Xuefan Yin, Chao Peng, Tomoki Ozawa, Andrea Blanco-Redondo
Summary: Topological photonics controls the behavior of light through the design of photonic structures, with potential applications in photonics devices. This roadmap surveys emerging areas of research within this field, with a focus on addressing fundamental scientific questions and presenting exciting opportunities for future research and developments.
JOURNAL OF PHYSICS-PHOTONICS
(2022)
Article
Engineering, Electrical & Electronic
Fernando D. Quesada Pereira, Antonio M. Huescar de la Cruz, Celia Gomez Molina, Alejandro Alvarez Melcon, Vicente E. Boria Esbert
Summary: An integral equation technique is proposed for the analysis of multiport H-plane microwave circuits composed of metallic and/or dielectric elements. The structure is divided into different regions, with access waveguide ports modeled using parallel plate Green's functions and the central region characterized by 2D rectangular cavity Green's functions. The use of this kind of Green's functions is novel, and the Ewald method is employed for accelerating the computation of these Green's functions. Results show high computational efficiency and good agreement with commercial software tools and measurements. Overall, this technique is highly valuable for the analysis of multiport microwave circuits.
IET MICROWAVES ANTENNAS & PROPAGATION
(2023)
Article
Chemistry, Multidisciplinary
Julian Klein, Zhigang Song, Benjamin Pingault, Florian Dirnberger, Hang Chi, Jonathan B. Curtis, Rami Dana, Rezlind Bushati, Jiamin Quan, Lukas Dekanovsky, Zdenek Sofer, Andrea Alu, Vinod M. Menon, Jagadeesh S. Moodera, Marko Loncar, Prineha Narang, Frances M. Ross
Summary: Atomic-level defects in van der Waals (vdW) materials are essential for quantum technologies and sensing applications. The magnetic semiconductor CrSBr, with a direct gap and rich magnetic phase diagram, exhibits optically active defects that are correlated with the magnetic environment. The narrow defect emission in CrSBr is related to both the bulk magnetic order and an additional defect-induced magnetic order. This study establishes vdW magnets like CrSBr as an exceptional platform for studying defects and creating tailor-made magnetic textures with optical access.
Article
Nanoscience & Nanotechnology
Guangwei Hu, Weiliang Ma, Debo Hu, Jing Wu, Chunqi Zheng, Kaipeng Liu, Xudong Zhang, Xiang Ni, Jianing Chen, Xinliang Zhang, Qing Dai, Joshua D. Caldwell, Alexander Paarmann, Andrea Alu, Peining Li, Cheng-Wei Qiu
Summary: Various optical crystals with opposite permittivity components have been observed and characterized in the mid-infrared regime. These crystals possess hyperbolic polaritons with large-momenta optical modes and wave confinement, making them promising for nanophotonic on-chip technologies. Monoclinic CdWO4 crystals are shown to exhibit symmetry-broken hyperbolic phonon polaritons and offer new opportunities for polaritonic phenomena.
NATURE NANOTECHNOLOGY
(2023)
Article
Nanoscience & Nanotechnology
Andrea Cordaro, Brian Edwards, Vahid Nikkhah, Andrea Alu, Nader Engheta, Albert Polman
Summary: As traditional microelectronic technology reaches its limits in speed and power consumption, there is a strong demand for novel computing strategies. Analogue optical computing has the advantage of processing large amounts of data at high speeds with negligible energy costs. Researchers have recently explored ultrathin optical metasurfaces for real-time image processing, particularly for edge detection. By incorporating feedback, they have also demonstrated that metamaterials can be used to solve complex mathematical problems, although this has been limited to guided-wave systems and large setups. This study presents an ultrathin Si metasurface-based platform for analogue computing, capable of solving Fredholm integral equations of the second kind using free-space visible radiation. The device combines an inverse-designed Si-based metagrating with a semitransparent mirror to perform the required Neumann series and solve the equation in the analogue domain at the speed of light. The use of visible wavelength operation enables a compact, ultrathin device that can be integrated on a chip and has high processing speeds.
NATURE NANOTECHNOLOGY
(2023)
Editorial Material
Materials Science, Multidisciplinary
Andrea Alu
Summary: Optical Materials Express Editor-in-Chief, Andrea Ali, has introduced new topic categories for the Journal, redefining the Journal scope and better reflecting the current state of this dynamic field of research.
OPTICAL MATERIALS EXPRESS
(2023)
Article
Nanoscience & Nanotechnology
Sander A. . Mann, Heedong Goh, Andrea Alu
Summary: Enabling strong nonlinear optical phenomena requires carefully designed photonic devices to maximize light-matter interactions. Topology optimization has been widely used in optimizing photonic devices due to its efficiency in dealing with large parameter spaces. However, the application of topology optimization in nonlinear effects in dielectric structures is limited.
Article
Nanoscience & Nanotechnology
Nikita Nefedkin, Michele Cotrufo, Andrea Alu
Summary: Nonreciprocity originating from classical interactions among nonlinear scatterers is explored in this work, offering a promising tool for quantum information processing and quantum computing. It is shown that large nonreciprocal responses can be achieved in nonlinear systems by controlling the position and transition frequencies of the atoms, without requiring a nonreciprocal environment. The connection between this effect and the asymmetric population of a slowly decaying dark state is demonstrated.
Article
Engineering, Electrical & Electronic
Clara Maximo-Gutierrez, Juan Hinojosa, Alejandro Alvarez-Melcon
Summary: This paper proposes a design method for Chebyshev band-pass filters based on groove gap waveguide (GGW) technology and evanescent mode for the first time. The design method reduces the analysis number and computation cost, and solves the discretization problem of the evanescent mode section. A fourth-order Chebyshev band-pass GGW filter is designed and the measured results show good agreement with electromagnetic simulation results. The proposed GGW band-pass filter has a reduced size and high-performance characteristics, making it beneficial for future emerging communications systems.
AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS
(2023)
Article
Chemistry, Analytical
Clara Maximo-Gutierrez, Juan Hinojosa, Jose Abad-Lopez, Antonio Urbina-Yeregui, Alejandro Alvarez-Melcon
Summary: This paper presents a compact wideband bandpass filter using groove gap waveguide (GGW) technology. The structure includes metallic pins along the GGW bottom plate and achieves a bandpass response by combining the high-pass characteristic of GGW and the low-pass behavior of the metallic pins. The filter design technique allows for a reduction in manufacturing complexity and the realization of high-performance filters.
Article
Engineering, Electrical & Electronic
Alejandro Pons-Abenza, Alejandro Alvarez-Melcon, Fernando Daniel Quesada-Pereira, Antonio Romera-Perez, Lara Arche-Andradas
Summary: This paper presents a novel quart-torus cavity for waveguide filters, which optimizes the footprint distribution of cavity filter structures without compromising their electrical performance. The resonator is constructed using a circular revolution process applied to a 2-D surface generator. The proposed cavities show similar theoretical unloaded-Q factors to their equivalent circular waveguide cavities, while offering advantages in physical layout disposition. A prototype is manufactured using selective laser melting technique and shows good agreement with simulations.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
(2023)
Article
Engineering, Electrical & Electronic
Antonio Manuel Huescar de la Cruz, Celia Gomez Molina, Fernando Daniel Quesada Pereira, Alejandro Alvarez Melcon, Vicente E. Boria Esbert
Summary: In this article, the Ewald method is used to accelerate the computation of the rectangular waveguide Green's functions derivatives. New approximation formulae are proposed to avoid the evaluation of computationally expensive complementary error functions. Numerical studies show a similar convergence rate for computing the original GFs and their derivatives. The newly derived expressions are useful for electromagnetic field evaluation and the analysis of rectangular cavities using integral equation formulations.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
(2023)
Article
Computer Science, Information Systems
J. M. Garcia-Barcelo, A. Alvarez Melcon, S. Arguedas Cuendis, A. Diaz-Morcillo, B. Gimeno, A. Kanareykin, A. J. Lozano-Guerrero, P. Navarro, W. Wuensch
Summary: This article introduces an electronic tuning method using ferroelectric materials for haloscopes in the search for dark matter axions. The proposed technique provides a more reliable and expanded tuning range compared to current mechanical tuning systems. The use of ferroelectric Potassium Tantalate (KTaO3 or KTO) as a tuning element achieves a major improvement over previous works and holds significant interest for the study of dark matter axions.
Article
Quantum Science & Technology
Nikita Nefedkin, Michele Cotrufo, Alex Krasnok, Andrea Alu
Summary: This study investigates nonreciprocal wave phenomena in atom-like quantum systems and reviews different approaches to isolation and nonreciprocity in quantum systems. It discovers that nonreciprocity induced by nonlinearity and discusses its underlying physics.
ADVANCED QUANTUM TECHNOLOGIES
(2022)
