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A 400-GHz Wideband High-Gain Quartz-Based Single-Layered Folded Reflectarray Antenna for Terahertz Applications
摘要： Compact high-gain antennas are highly desired in the high speed terahertz (THz) wireless system, especially for the space limited application such as the high speed inter-link inside the high density wireless communication base station. To this end, a 400-GHz folded reflectarray (FRA) antenna with high gain, high aperture efficiency and compact profile is proposed in this paper. It is composed of a feed source, a single-layered reflectarray using a lithography process on quartz, and a wire-grid polarizer implemented by the printed-circuit-board (PCB) technology. A 3-D printed fixture is used to assemble all parts together. In order to design accurately the THz electromagnetic properties of the supporting dielectric materials are extracted by using a THz time-domain spectrometer system. Then, a single-layered phasing element, made up of a pair of orthogonally I-shaped structures with an open square ring, is proposed and designed based on the extracted material characteristics. Both phase compensation and polarization conversion can be realized by the proposed unit cell. A reflectarray is designed by using the proposed phasing element with the conventional array synthesizing theory, and a THz grid polarizer is designed with strips on a 0.127 mm Taconic TLY-5 substrate. The THz grid is placed in front of the THz feed and the reflectarray, which is fully reflective to the feed and transparent to the reflectarray. All components of the FRA antenna have been fabricated and assembled. Experiments show that the FRA prototype has a peak gain of 33.66 dBi at 400 GHz with an aperture efficiency of 33.65%, and a 3-dB gain bandwidth of 16% (357-421 GHz).
关键词： terahertz,3-D printing,high-gain,material characteristics,quartz substrate,single-layer,Folded reflectarray antenna,THz time-domain spectrometer
更新于2025-09-10 09:29:36
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Far Infrared and THz Detectors: Principles of Operation and Figures of Merit
摘要： In this paper we discuss characteristics of detectors and their experimental applications in the Far Infared (FIR) and lower THz spectral range: 50-3000 GHz (6mm-100 μm), with special attention to Plasma Diagnostics, THz-TDS and Free Electron Lasers (FEL). The International System of Units (SI) will be used throughout.
关键词： THz-TDS,Far Infrared,THz Detectors,Plasma Diagnostics,Free Electron Lasers
更新于2025-09-09 09:28:46
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Tunable terahertz metamaterial by using three-dimensional double split-ring resonators
摘要： We present an optically tunable terahertz (THz) metamaterial by using three-dimensional double split-ring resonators (3D-DSRR), which shows superior properties in adjustability. They exhibit tunable single-band and dual-band resonances by changing height between inner and outer SRRs. The maximum tuning range of dual-band resonance is 0.55 THz from the resonance of 0.45 THz shifted to the resonance of 1.00 THz. The corresponding tuning range of free spectrum range (FSR) spanned two resonances can be tuned from 0.20 THz to 0.75 THz. By changing radius of inner SRR from 14.5 μm to 22.5 μm, the tuning range of resonance is 0.40 THz. While changing the height between inner and outer SRRs and kept the radiuses of inner and outer SRRs as constant as 22.5 μm, 3D-DSRR can be tuned to have two resonances and then merge into one resonance. 3D-DSRR shows a tunable and switchable resonance for single-band and dual-band characteristics. These characterizations are very suitable for the use of tunable multi-resonance applications. To further investigate the stability of 3D-DSRR, the rotation angles of inner and outer SRRs are modified from 0° to 180°, respectively. The corresponding resonances are identical. Such results indicate the proposed device with high stability to allow manufacturing tolerance and potentially to be used in wearable electronic devices, pressure sensors, and other fields.
关键词： Metamaterial,THz resonator,THz modulator
更新于2025-09-09 09:28:46
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Effect of MIT in epitaxial VO <sub/>2</sub> films on THz transmittance
摘要： The development of THz technologies (communication, imaging, spectroscopy etc.) requires the design of materials for high-speed modulation of radiation in THz range. For such applications, the thin films based on oxides showed a metal-insulator transition (MIT) are interesting due to large different of optical transmittance before and after critical point. Among the oxide materials with MIT vanadium dioxide, which has a transition temperature the closest to the room temperature (68oC for bulk samples), is of particular interest, with the MIT characterized by a record speed (<1 ps) and a large amplitude (a change in the conductivity is 105 times for single crystals). It is known that the MIT transition in VO2 is accompanied by a first-order phase transition, while the crystalline structure from the monoclinic (crystal type MoO2) with the properties of the semiconductor transforms into a tetragonal (rutile type) with metallic conductivity. The electronic transition in the vanadium dioxide can be caused by the temperature, the electric field and laser radiation. A set of these unique properties makes vanadium dioxide a promising key component of optoelectronic devices (switches, modulators, lenses, etc.) for the THz range controlled by thermal action, electric voltage or laser pulse.
关键词： vanadium dioxide,epitaxial films,metal-insulator transition,THz transmittance,THz technologies
更新于2025-09-09 09:28:46
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Terahertz Gyrotrons with Unique Parameters
摘要： Development of high power THz sources play important role for development advance technologies in physics, chemistry, biology, medicine. The main goal of this report is present together data about gyrotron development and the most striking examples of modern applications. The paper describes some features of THz tubes. The key information about pulsed and CW tubes is given. The described gyrotrons demonstrate (in some specific combinations) extremely low voltage and beam current, narrow frequency spectrum, wide range frequency tuning. Novel schemes of high frequency gyrotrons are analyzed. Examples of gyrotron based experiments for spectroscopy, data transmission and localized gas discharge are presented.
关键词： spectroscopy,data transmission,THz sources,gyrotrons,gas discharge
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) INTERNATIONAL CONFERENCE OF COMPUTATIONAL METHODS IN SCIENCES AND ENGINEERING 2018 (ICCMSE 2018) - Thessaloniki, Greece (14–18 March 2018)] - Investigation of terajets produced by dielectric parallelepiped structure
摘要： In this article the generalized results of full width at half-maximum intensity (FWHM) of the “terajets” are presented for a parallelepiped structure made of eight different photopolymers in the frequency range of 0.04-0.2 THz. Its S-parameters were obtained in COMSOL Multiphysics software. After the analysis of the transmission and reflection spectra the “terajet” effect was observed at the specific resonance frequencies. This gives us an opportunity to predict this effect and create narrow-band devices based on it in THz imaging and sensing.
关键词： sensing,photopolymers,THz imaging,COMSOL Multiphysics,dielectric parallelepiped structure,terajets
更新于2025-09-09 09:28:46
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A THz Receiver with Novel Features and Functionality
摘要： The presented THz receiver is based on an antenna coupled titanium micro-bolometer. A new geometrical design improves the robustness and extends the lifetime of the sensor. A study of sensor lifetime using different biasing currents is presented. The lifetime was verified by several tests and over 1000 operating hours. A new micro-bolometer sensitivity measurement algorithm is presented in the paper and measurement results using the proposed algorithm are shown. The new algorithm was developed to be suitable for ATM production testing. In the paper, a novel feature called “sensitivity boosting” is described, together with its influence on sensitivity and lifetime.
关键词： micro-bolometer lifetime,sensitivity boosting,THz micro-bolometer
更新于2025-09-09 09:28:46
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Characteristics of VOx Microbolometer on Si<inf>3</inf>N4/SiO<inf>2</inf> Membrane Fabricated by Deep-RIE and XeF2 Vapor Etching for THz-detectors
摘要： VOx thin films were fabricated on Si3N4/SiO2/Si substrates by metal-organic decomposition (MOD). Then, a VOx microbolometer was fabricated on a Si3N4/SiO2 membrane. A membrane was realized by dry etching of the backside of the Si substrate using a Deep-RIE and XeF2 vapor etching with a good reproducibility. The DC sensitivity of the bolometer on membrane was 2310 W-1. This value was about 15 times higher than that of the VOx microbolometer on the Si3N4/SiO2/Si substrate and about two orders of magnitude higher than that of the Bi microbolometer on a dielectric substrate.
关键词： Si3N4/SiO2 membrane,THz-detectors,VOx microbolometer,Deep-RIE,XeF2 vapor etching
更新于2025-09-09 09:28:46
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Terahertz waves radiated from two plasma filaments with opposite directions
摘要： The interaction and the coupling between the plasma filaments introduce some ultrafast phenomena, which not only reveal deep physical mechanisms, but also provide clues to develop the plasma filament-based applications. In this paper, the terahertz (THz) radiation from two plasma filaments with opposite directions, which are produced by focusing two counter propagating femtosecond laser pulses with a pair of off-axis-parabolic mirrors, is measured using electro-optic sampling detection method. The experimental results show that the pre-plasma weakens the THz radiation in the cases of with and without an external biased field. The lifetime of the plasma filament is estimated using the time evolution of the THz peaks. It is found that the THz radiation keeps weaker even when one pump pulse is 300 ps before the other one, which indicates that the lifetime of the plasma filament is longer than 300 ps. In addition, the THz pulses have similar shapes at different time delays between two pump laser pulses. Its underlying physical mechanisms are discussed as well.
关键词： THz radiation,filaments,opposite directions
更新于2025-09-09 09:28:46
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Metasurface-Based THz Dual-Band Absorber Sensor for the Measurement of Refractive Index Variations of Chemical and Biological Substances
摘要： In this paper we report on the results of the simulations of the electromagnetic properties of a metasurface composed of a 2D-array of plasmonic nanoantennas acting as polarisation insensitive dual band THz perfect absorber able to achieve absorption coefficients and quality factors up to 99.6% and 122, respectively. The 2D-array is designed on top of a polyimide flexible film separating it from an Ag ground layer. The plasmonic nanoantenna is composed of two Ag quadrangular rings and an Ag diamond-shape dot is placed at their geometrical centre. The absorption resonances show a linear frequency shift with respect to variations of the refractive index of transparent substances adsorbed on the metasurface. This allows the dual-band absorber to be employed as a sensor of the chemical/physical modifications taking place on the substance. In particular, in terms of the refractive index units, the sensor based on the dual-band absorber can achieve sensitivities up to 310 GHz/RIU.
关键词： THz perfect absorber,functionalised metasurfaces,plasmonic sensors
更新于2025-09-09 09:28:46