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Wideband Rectangular Double-Ring Nanoribbon Graphene-Based Antenna for Terahertz Communications
摘要： A wideband nanoribbon graphene-based antenna with double rectangular rings for terahertz (THz) applications is presented. The wideband and efficient graphene-based antenna on physical parameters is developed in this paper. The antenna has a wide impedance bandwidth of 26% at the center frequency of 1 THz, minimum return loss equal to 24 dB and average radiation efficiency approximately equal to 44% is obtained. An average gain of 2.45 dB is achieved at the operational frequency band. The goal of this paper is to provide an antenna with capabilities of being wideband, efficient and re-configurable with a simple and single-layer structure for THz communication.
关键词： Double-ring antenna,wideband antenna,graphene,terahertz,THz,re-con?gurable,nanoribbon antenna
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE/MTT-S International Microwave Symposium - IMS 2019 - Boston, MA, USA (2019.6.2-2019.6.7)] 2019 IEEE MTT-S International Microwave Symposium (IMS) - Silicon-Micromachined Waveguide Calibration Shims for Terahertz Frequencies
摘要： A new method of realising precision waveguide shims for use in THz Through-Re?ect-Line (TRL) calibrations, based on silicon-micromachining, is introduced. The proposed calibration shims combine a thin λ/4 silicon layer, co-fabricated with a thicker layer which provides mechanical support. This design overcomes the limitations of CNC milling for the creation of calibration shims, facilitating use of standard TRL calibration at currently challenging frequencies. The novel shim ?ts inside the inner recess of a standard waveguide ?ange and is compatible with conventional ?ange alignment pins. Five micromachined shims were fabricated in a silicon-on-insulator process for operation in the WM-570 waveguide band (325 – 500 GHz). The fabricated shims show excellent performance across the entire band, with return loss in excess of 25 dB, insertion loss below 0.2 dB and high uniformity between samples. Veri?cation reveals that the micromachined shims have an electrical length within 2% of the expected value. Comparative measurements of a DUT calibrated with the proposed shim and a previously un-used conventional metallic shim show that the novel concept offers equivalent, if not better, performance. The mechanical design of the micromachined shim and the rigid nature of silicon ensure that it will not suffer from performance degradation with repeated use, as is problematic with thin metallic shims. This work enables the creation of low-cost, highly-repeatable, trace- able calibration shims with micrometer feature-sizes and high product uniformity, surpassing the limits of current techniques.
关键词： calibration,micromachining,TRL,terahertz,waveguide,THz
更新于2025-09-11 14:15:04
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Study on Detecting Dielectric Properties of Typical Electrical Insulation Materials by Terahertz Wave Spectroscopy
摘要： The dielectric properties of the electrical insulation materials is of great importance to the safe operation of the power system. As a promising technique in the field of material testing and with the very adaptive physical modeling of wave transmission process, terahertz wave was used to measure the dielectric properties of five commonly used insulation materials by two methods in this paper. When excluding the echo pulse from the reference signal and the sample signal, a better signal-noise ratio and a wider effective frequency band of spectrums can be obtained. Alternatively, the dielectric properties can also be achieved by separating the main pulse and echo pulse from the sample signal. The latter method makes the sampling of reference signal unnecessary. Furthermore, the dielectric properties of materials were also measured on a relative lower frequency band (1Hz-1MHz) by the broadband dielectric spectrometer. Compared with a relatively lower frequency band, due to the polarization, the dielectric constant of the tested insulation materials was lower on the terahertz band while the dielectric loss tangent was generally higher except the epoxy resin.
关键词： Dielectric properties,Terahertz wave,Insulation materials,Broadband dielectric spectrometer
更新于2025-09-11 14:15:04
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[IEEE 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama) - Toyama (2018.8.1-2018.8.4)] 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama) - Characterization of Terahertz Plasmonic Structures Based on Metallic Wire Woven Meshes
摘要： A THz plasmonic structure based on metallic wire woven meshes to support Fano resonance is presented in numerical calculation. The structure unit of the woven metal wire is critical to perform this resonance ?eld due to its asymmetry, which is compared with the symmetry of metal-hole-array. Using di?erent bent wires with various curvatures on the woven metal wire structure can modulate the spectral properties of resonance ?eld in the frequency and bandwidth. High Q-factor resonance are thus optimized via the dimensions of the wire bending section and realized to con?ne a large volume of resonance ?eld.
关键词： Fano resonance,Terahertz,plasmonic structures,metallic wire woven meshes
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Control of Terahertz Nonlinearity in Graphene by Gating
摘要： We study the dependence of the terahertz (THz) nonlinearity of graphene and its temporal dynamics on the free carrier concentration by THz-pump/THz-probe spectroscopy of a gated graphene at room temperature. The strong THz nonlinearity is attributed to electron heating by the driving THz field and shows a drastic dependence on the background electron concentration, demonstrating a wide-range tunability of the THz nonlinearity of graphene.
关键词： Gating,Electron heating,Graphene,Nonlinearity,Terahertz
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Photonic Bandgap Bragg Waveguide-based Terahertz Microfluidic Sensor
摘要： A 3D printed photonic bandgap Bragg waveguide-based resonant fluidic sensor operating in the THz spectral range is theoretical analyzed and experimental studied. The liquid analytes injected into a microfluidic channel inside the reflector region result in anticrossing of the dispersion relation between the core-guided mode and the defect state. By tracking the spectral positions of the induced absorption dips and phase changes on the transmission spectra, the fluidic sensor exhibits a sensitivity of 110 GHz/RIU and a resolution of 0.0045 RIU. The sensor provides a non-contact measurement method for real-time monitoring of the refractive index change of liquid flow in practical applications.
关键词： 3D Printing,Photonic Bandgap,Microfluidic Sensor,Bragg Waveguide,Terahertz
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Spectroscopic characterization at THz frequencies of glucose-based biomaterials: paramylon, paramylon-ester and cellulose
摘要： The terahertz (THz) spectroscopy of paramylon (β-1,3-glucan) and paramylon-ester extracted from microalgae called as Euglena have been studied by Fourier Transform Infrared Spectrometer (FT-IR) in a frequency range from 0.3 to 9 THz. The absorption spectra of paramylon were analyzed by comparing them with cellulose that has a similar long-chain -(C6H10O5)n-structure with paramylon. The differences in absorption features between paramylon and cellulose may be caused by their different chain structures. The broad absorption spectra of paramylon-ester can be attributed to some sort of disorder of long-chain molecular vibration modes due to the substitution of propionyl chloride and long-chain acid chloride by esterification.
关键词： microalgae,Euglena,paramylon-ester,paramylon,cellulose,terahertz spectroscopy,Fourier Transform Infrared Spectrometer
更新于2025-09-11 14:15:04
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - The terahertz near-field response of graphene layers and graphene structures
摘要： We report on the experimental study of the scattering and the near-field interaction of a THz electromagnetic field with graphene layers near the probe of a terahertz near-field microscope. There are resonance lines in the spectrum for a graphene monolayer-based transistor structure, which is possibly due to the strong plasmon response at terahertz frequencies and the manifestation of plasmon interference in the graphene strip.
关键词： terahertz,near-field microscopy,graphene,plasmon response
更新于2025-09-11 14:15:04
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A Hybrid THz Imaging System With a 100-Pixel CMOS Imager and a 3.25–3.50 THz Quantum Cascade Laser Frequency Comb
摘要： The terahertz frequency range beyond 3 THz has exciting potential to have a transformative impact in a wide range of applications, including chemical and biomedical sensing, spectroscopy, imaging, and short-distance wireless communication. While there have been significant advancements in silicon-based THz imagers in the frequency ranges below 1 THz, technological development beyond 3 THz has been impeded by the lack of solid-state sources in this frequency range. In addition, the design space beyond 3 THz opens up fundamentally new challenges across electronics and the electromagnetic interface. In this spectral range, the wavelength is small enough (λox ≈ 50 μm at 3 THz) that a vertical via from the top antenna layer to the detector is a distributed element (transmission line or radiator). In this letter, we follow a careful circuits-electromagnetics co-design approach toward a hybrid imaging system with a 100-pixel CMOS imager that interfaces with a THz quantum cascade laser frequency comb that spans 3.25–3.5 THz with mode spacing of 17 GHz. The array chip, while designed for an optimal operation across 2.7–2.9 THz, demonstrates an average noise equivalent power (NEP) (across pixels) of 1260 pW/√Hz between 3.25–3.5 THz and a projected NEP of 284 pW/√Hz across the design range of 2.7–2.9 THz. To the best of our knowledge, we demonstrate for the first time full THz imaging in a hybrid quantum cascade laser (QCL)–CMOS fashion. This approach allows future works to leverage both QCL and CMOS technologies to demonstrate new technological advances for systems in the 1–10 THz range.
关键词： hybrid imaging,quantum cascade laser,silicon,THz imaging,CMOS,terahertz,imaging,detector
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Antenna Tapering Strategy for Near-Field Enhancement Optimization in Terahertz Gold Nanocavities
摘要： Plasmonic nanoantennas (NAs) have received a growing attention in recent years due to their ability to confine light on sub-wavelength dimensions. More recently, this property has been exploited in the terahertz (THz) frequency range (0.1-10 THz) for enhanced sensing and spectroscopy, as well as for more fundamental investigations. These applications typically require high local electric fields that can be achieved by concentrating THz radiation into deeply sub-wavelength volumes located at the NAs extremities. However, the achievable near-field enhancement values are severely limited by the poor resonance quality factor of traditional rod-shaped THz NAs. Unlike what is commonly assumed in the infrared domain, here we show that an optimal NA tapering angle can be effectively introduced to obtain higher quality factors and, at least, twofold higher local near-field enhancement in comparison with standard (wire-like) dipolar THz NAs. To evaluate how the tapering angle affects the NA performance, a simplified quasi-analytical model was first developed. Each NA is considered as a truncated cone constituted by a sequence of gold cylinders of increasing radii, so that the effective refractive index of the surface mode propagating along the NA changes gradually along the main axis. Once the reflection coefficients for the surface mode at both extremities are retrieved, a NA can be interpreted as a Fabry-Perot resonator and its resonances can be analytically calculated. This model reveals a trade-off between large tapering angles (resulting in a low reflection coefficient at the large extremity) compared to small tapers (which are affected by high propagation losses for the surface mode), leading to an optimal taper angle. FEM-based simulations (COMSOL Multiphysics) were then used to confirm this prediction. 60-nm-thick gold tapered NA dimers were designed with 45-μm-long arms (in order to resonate at around 1 THz) and with their facing tips (100-nm-wide) separated by a 30 nm gap, thus realizing a bowtie geometry. We numerically investigated the near-field enhancement in the gap between the NAs, varying the tapering angle α from 0° to 10°. We found that in planar gold NA dimers the near field grows as the tapering angle increases up to α = 3.4°, where the maximum is reached. In order to experimentally confirm these results, arrays of gold tapered NA dimers were fabricated by electron beam lithography on a high resistivity silicon substrate. A transmission characterization by means of THz time-domain (far-field) spectroscopy was then carried out on the fabricated NA arrays revealing, as expected, an increase of the resonance quality factor for the optimized tapered geometry. In conclusion, we demonstrated an effective, yet simple, way to further boost and engineer the local field enhancement of THz NAs.
关键词： Plasmonic nanoantennas,tapering angle,near-field enhancement,quality factor,terahertz
更新于2025-09-11 14:15:04