Article
Engineering, Electrical & Electronic
Ahmed A. Ibrahim, Shaymaa M. Gaber
Summary: This paper introduces a graphene-based two ports antipodal Vivaldi antenna with improved gain for THz applications. The reconfigurability of the antenna is achieved by changing the external DC Volt, which in turn changes the graphene chemical potential and the operating frequency. Frequency selective surfaces (FSS) with a metallic patch are used to enhance the antenna gain. The MIMO antenna has good performance and is suitable for IoT THz applications.
OPTICAL AND QUANTUM ELECTRONICS
(2023)
Article
Chemistry, Multidisciplinary
Yanfei Mao, E. Shiju, Chungeng Zhu
Summary: This paper presents a new and simple design method for end-fire antenna arrays, which can easily design and construct antenna arrays with high gain, simple design and compact size.
APPLIED SCIENCES-BASEL
(2021)
Article
Computer Science, Information Systems
Hengfei Xu, Boyu Sima, Pu Wei, Lei Tang, Shu Jiang, Chuanqing Liu
Summary: This article presents the design and performance of a planar wideband circularly polarized end-fire antenna for millimeter-wave applications. The antenna achieves wide axial ratio performance by exciting a horizontally polarized electric dipole and an enhanced magnetic dipole. It features a simple and compact structure, easy fabrication and integration.
Article
Engineering, Electrical & Electronic
Li Yi, Ryohei Kaname, Ryoko Mizuno, Yihan Li, Masayuki Fujita, Hiroshi Ito, Tadao Nagatsuma
Summary: In this study, a frequency-modulated continuous-wave photonic radar system was proposed for three-dimensional imaging in the THz band. The system achieved high-quality 3D imaging by calibrating the laser source's frequency sweep linearity and introducing the synthetic aperture radar (SAR) technique to overcome the limitations of fixed focal distance.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Computer Science, Information Systems
Amalina Athira Ibrahim, Bo Li, Shenghong Ye, Takashi Shiramizu, Hanwei Chen, Yuya Mikami, Kazutoshi Kato
Summary: A new phase stabilization method using backward-directional lightwave overlapped with the THz wave generation system was proposed. By photomixing, the phase of THz waves can be controlled in the optical domain, resulting in stable THz wave generation. Experimental results demonstrated error-free transmission at high modulation frequencies.
Article
Computer Science, Information Systems
Henri Kahkonen, Juha Ala-Laurinaho, Ville Viikari
Summary: This study presents a modular dual-polarized Vivaldi antenna array design for the frequency range of 18-30 GHz. It consists of antenna and RF modules, allowing assembly of antenna arrays of various sizes and shapes. The experimental results confirm the feasibility and performance of the design.
Article
Engineering, Electrical & Electronic
Alvaro J. Pascual, Muhsin Ali, Thomas Batte, Fabien Ferrero, Laurent Brochier, Olivier de Sagazan, Frederic van Dijk, Luis E. Garcia Munoz, Guillermo Carpintero Del Barrio, Ronan Sauleau, David Gonzalez-Ovejero
Summary: This paper presents a technique for beam switching in wireless links using a photonically-excited antenna array at E-band. The authors discuss the proposed technique applied to photonic-enabled (sub)millimeter-wave transmitters and present the implementation and validation of the system. The system allows for broadband operation with switchable and directive beams.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Siyu Chen, Wenlu Shi, W. Ho
Summary: We demonstrate rectification spectroscopy (RS) for single molecules using continuous-wave terahertz (CW THz) radiation at the tunneling junction of a scanning tunneling microscope (STM) at 8 K. CW THz-RS offers a new technique for studying single-molecule vibrational and magnetic excitation spectroscopy, alongside inelastic electron tunneling spectroscopy (IETS). By comparing IETS and THz RS, we find that CW THz induces a sinusoidal bias modulation with an amplitude that is linearly dependent on the THz far-field amplitude. This THz-induced bias modulation amplitude appears to be sensitive to the alignment of the THz beam but insensitive to changes in the tunneling gap smaller than the THz wavelength.
Article
Optics
Kazutoshi Kato
Summary: Beam forming and beam steering are essential technologies for the practical application of high-frequency electromagnetic waves, while beam control technology using a phased array for terahertz waves above 100 GHz is necessary for achieving high-speed wireless communication. Adjusting the beam of terahertz waves improves not only the power efficiency but also the security of wireless transmission at the physical layer.
Article
Computer Science, Information Systems
Hijab Zahra, Wahaj Abbas Awan, Wael Abd Ellatif Ali, Niamat Hussain, Syed Muzahir Abbas, Subhas Mukhopadhyay
Summary: In this paper, an end-fire antenna for 28 GHz broadband communications is proposed with its MIMO configuration for pattern diversity applications, characterized by reasonable gain, high isolation, good envelope correlation coefficient, broad bandwidth, and high diversity gain. The antenna was fabricated and verified by experimental measurements, showing a wide -10 dB bandwidth from 26.25 GHz to 30.14 GHz for 5G communication systems. Comparisons with state-of-the-art mm-wave end-fire antennas demonstrate the worth of the proposed work in terms of operational bandwidth, electrical size, and various MIMO performance parameters.
Article
Engineering, Electrical & Electronic
James P. Seddon, Michele Natrella, Xiaoli Lin, Chris Graham, Cyril C. Renaud, Alwyn J. Seeds
Summary: This paper discusses the optimization of high-speed photodiodes in terms of bandwidth and output power in the Terahertz frequency band. A numerical modeling tool for evaluating antenna coupled uni-travelling carrier photodiodes and experimental evaluation of fabricated designs are presented. Additionally, a thermal analysis and pulsed measurements of the output power saturation are also discussed for the photodiodes.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2022)
Article
Engineering, Electrical & Electronic
P. Prasanna Kumar, Prerna Saxena
Summary: The proposed antenna utilizes a novel metamaterial design to cover the 20-40 GHz frequency range, demonstrating high gain and stable radiation pattern in a compact size. It is suitable for wideband millimeter wave imaging applications, specifically for detecting concealed weapons and structural defects.
JOURNAL OF INFRARED MILLIMETER AND TERAHERTZ WAVES
(2022)
Article
Multidisciplinary Sciences
Peiying Lin, Yuting Wu, Zhouyi Wu, Ruofan Zhuo, Jiangtao Huangfu
Summary: This study proposes an optically frequency-reconfigurable antenna with multiband characteristics using photodiodes. The antenna can be reconfigured at multiple low frequencies and remains stable at high frequencies. By illuminating different photodiodes, the antenna can switch between three narrowband modes. The antenna also has good working characteristics in specific frequency ranges, making it suitable for various applications.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Electrical & Electronic
Li Zhou, Min Tang, Jiawei Qian, Yue-Ping Zhang, Junfa Mao
Summary: In this article, a new type of Vivaldi antenna with enhanced heat dissipation is proposed and manufactured using 3-D printing and printed circuit board (PCB) technologies. The antenna achieves a wide bandwidth and gain by employing a longitudinal slot for feeding the Vivaldi radiation structure. The measured results are in good agreement with the simulated ones, indicating the potential application of the proposed antenna in 5G millimeter-wave systems.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2022)
Article
Computer Science, Information Systems
Raza Ullah, Sadiq Ullah, Farooq Faisal, Rizwan Ullah, Dong-you Choi, Ashfaq Ahmad, Babar Kamal
Summary: In this study, an antipodal Vivaldi antenna was designed for 5th generation (5G) mobile communication and Ku-band applications. The antenna has three layers and compact size. It covers multiple frequency bands, shows high efficiency, and is suitable for 5G communication and radar applications.
Article
Optics
Ram S. Prakash, Rajesh Kumar, Anirban Mitra
Summary: This paper proposes a lithography-free spectrally tunable perfect absorber that utilizes an asymmetric Fabry-Perot cavity with Ge2Sb2Te5 (GST) as the cavity layer. The device achieves a maximum absorption of 99.7% at 1550 nm when GST is in the amorphous state under specific angle of incidence and polarization. When GST transforms from amorphous to crystalline, the absorption spectrum switches to longer wavelengths. The tuning range is about 866 nm, and the absorption remains above 99% throughout the tuning range. The crystallinity ratio of GST can be varied by applying voltage pulses, and electrothermal cosimulations confirm the phase change throughout the GST layer. Additionally, by reamorphization of GST, the absorption spectrum can be switched back, enabling reconfigurable perfect absorption. This work demonstrates a feasible approach for achieving a tunable perfect absorber that covers the 1550 nm communication wavelength window as well as the emerging optical communication window around 2 μm wavelength.
Article
Optics
Mohammad Faraz Abdullah, Nadir Ali, Vilson R. Almeida, Roberto R. Panepucci, Yiwei Xie, Daoxin Dai, Rajesh Kumar
Summary: This study presents a thorough investigation of a photonic memory with phase change material in a partially etched silicon waveguide at a wavelength of 1550 nm. The results show that the proposed approach has better performance than other methods that integrate the phase change material on top of or fill the waveguide.
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Uttam Nandi, Moritz Scheer, Hong Lu, Justin C. Norman, Arthur C. Gossard, Sascha Preu
Summary: This article presents the investigation of bias-dependent carrier dynamics in ErAs:In(Al)GaAs superlattice photoconductors and compares the results to a theoretical model. The carrier lifetime decreases with bias for materials without InAlAs layer, and for materials with SL consisting of InGaAs and high-barrier InAlAs layer, the carrier lifetime features a bias-dependent fast decay followed by a bias-independent slower decay. The THz spectra recorded confirm the decrease in carrier lifetime, and the power for high-frequency components shows improvement in agreement with theoretical expectations.
IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Benedikt Leander Krause, Amlan Kusum Mukherjee, Sascha Preu
Summary: In this paper, a photonic spectrum analyzer is presented for measuring spectral power, linewidth, and harmonics of signals in the terahertz range. By using a photonically generated local oscillator frequency and a photoconductor, the signal under test can be downconverted and measured. The measurement results demonstrate that this method is suitable for measuring signals transported via a dielectric waveguide and characterizing on-chip sources.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2023)
Article
Optics
Amlan Kusum Mukherjee, Sven Wassmann, Konstantin Wenzel, Bjoern Globisch, Robert Kohlhaas, Lars Liebermeister, Sascha Preu
Summary: Material characterisation and imaging applications using terahertz radiation have gained interest due to their potential for industrial applications. This work presents a vector-based implementation of the gradient descent algorithm to fit measured transmission and reflection coefficients of multilayered objects to a scattering parameter-based model. The algorithm extracts thicknesses and refractive indices of the layers with a maximum 2% error margin.
Article
Chemistry, Analytical
Christoph Hoog Antink, Romina Schulz, Maurice Rohr, Konstantin Wenzel, Lars Liebermeister, Robert Kohlhaas, Sascha Preu
Summary: We used a high-sampling rate terahertz homodyne spectroscopy system to estimate thoracic movement during breathing of healthy subjects at different frequencies. The THz system provided amplitude and phase information, and the motion signal was derived from the raw phase data. The electrocardiogram (ECG) signal recorded with a chest strap showed suboptimal performance, while the THz system showed good agreement with the measurement protocol, resulting in a root mean square estimation error of 1.40 BPM for all subjects.
Article
Chemistry, Analytical
Rahul Yadav, Florian Ludwig, Fahd Rushd Faridi, J. Michael Klopf, Hartmut G. Roskos, Sascha Preu, Andreas Penirschke
Summary: This study presents the characterization of a Zero-bias Schottky diode-based THz detector that operates up to 5.56 THz. The detector was tested using a table-top system up to 1.2 THz and a Free-Electron Laser facility at frequencies ranging from 1.9 to 5.56 THz. Two measurement techniques were employed to differentiate between sub-ns-scale and ms-scale responsivity. The results show that the detector has a noise equivalent power (NEP) in the range of 10-17 pW/vHz and a voltage and current responsivity of approximately 500 kV/W and 100 mA/W, respectively, within the frequency range of 0.2 to 1.2 THz.
Article
Engineering, Electrical & Electronic
Amlan Kusum Mukherjee, Sven Wassmann, Sascha Preu
Summary: By using digital postprocessing technique, the noise in terahertz systems can be significantly reduced without adding too much processing time, thus improving the signal-to-noise ratio, expanding the operational bandwidth, and enhancing the data quality.
IEEE TRANSACTIONS ON TERAHERTZ SCIENCE AND TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Sumer Makhlouf, Oleg Cojocari, Martin Hofmann, Tadao Nagatsuma, Sascha Preu, Nils Weimann, Heinz-Wilhelm Huebers, Andreas Stoehr
Summary: This manuscript reports on the latest achievements in terahertz sources and receivers, providing a comprehensive overview of their working principles and applications in THz systems.
IEEE JOURNAL OF MICROWAVES
(2023)
Correction
Engineering, Electrical & Electronic
Mohammad Faraz Abdullah, Amlan K. Mukherjee, Rajesh Kumar, Sascha Preu
JOURNAL OF INFRARED MILLIMETER AND TERAHERTZ WAVES
(2022)
Article
Computer Science, Information Systems
Benedikt Leander Krause, Anuar De Jesus Fernandez Olvera, Sascha Preu
Summary: This paper presents an ultra-broadband and inexpensive photonic spectrum analyzer for wireless signals, which has a wide frequency coverage from microwave to terahertz range. By down-converting the signal using an optical local oscillator, the system achieves a large tuning range without the need for component interchange. Compared to an electronic spectrum analyzer, our system offers similar performance at a fraction of the cost.
Review
Nanoscience & Nanotechnology
Ping-Keng Lu, Anuar de Jesus Fernandez Olvera, Deniz Turan, Tom Sebastian Seifert, Nezih Tolga Yardimci, Tobias Kampfrath, Sascha Preu, Mona Jarrahi
Summary: Efficient terahertz generation and detection are crucial for high-performance terahertz systems. Photomixing process in photo-absorbing semiconductor material enables the generation of terahertz frequency components, which can be radiated or mixed with incoming terahertz waves in terahertz emitters and detectors. Current methods often use semiconductors with short carrier lifetimes, resulting in limited photoconductive gain and optical responsivity. Exploring alternative techniques without relying on these semiconductors is of great importance.
