- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Active Thermal Control of 5 nm Gap Terahertz Antennas
摘要： Metallic nanostructures are combined with various active materials for electrical, optical, and thermal modulations of their optical properties. In particular, for the thermal modulation, deformation of metallic nanostructures at high temperatures limits the applications to relatively low temperatures, where thermal expansion of metals is negligible. Here, a unique regime is reported where terahertz (THz) waves transmitting through 5 nm wide slot antennas can be significantly modulated via controlled thermal expansion of metals without active materials. The normalized amplitude is modulated by 20% and the resonant frequency by 22% at an elevated temperature of 150 °C, indicating a decrease in the gap width by 50%. The extreme width-to-length ratio of the THz slot antennas compensates the small thermal expansion coefficient of metals, enabling the gap width to be considerably changed. COMSOL simulation and coupled-mode method (CMM) calculation quantitatively support the experimental data. This works suggests a new possibility of thermally active metallic nanostructures.
关键词： metamaterials,active modulation,terahertz spectroscopy,nanogaps,thermal expansion
更新于2025-09-04 15:30:14
-
Encyclopedia of Spectroscopy and Spectrometry || Terahertz Imaging and Spectroscopy Methods and Instrumentation
摘要： Terahertz Imaging and Spectroscopy Methods and Instrumentation
关键词： Instrumentation,Terahertz,Spectroscopy,Imaging
更新于2025-09-04 15:30:14
-
[IEEE 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Chengdu (2018.3.26-2018.3.28)] 2018 IEEE International Conference on Computational Electromagnetics (ICCEM) - Terahertz Wave Scattering by Skin Cancer Tissues
摘要： This paper presents an approximate method for analysis of scattering by skin cancer tissues at Terahertz. The complex dielectric parameters of skin tissues are based on the double Debye model. The cancer tissue is taken to be a weak disturbance to the bulk skin organ. Born approximation is used to calculate the scattering field by the equivalent volume currents of cancer tissues in a layered configuration. Discrete complex image method is employed to evaluate the Sommerfeld-type integral. Numerical results show that the proposed approach is efficient and viable.
关键词： Born approximation,Terahertz scattering,skin cancer tissues,double Debye model
更新于2025-09-04 15:30:14
-
[IEEE 2018 IEEE SmartWorld, Ubiquitous Intelligence & Computing, Advanced & Trusted Computing, Scalable Computing & Communications, Cloud & Big Data Computing, Internet of People and Smart City Innovation (SmartWorld/SCALCOM/UIC/ATC/CBDCom/IOP/SCI) - Guangzhou, China (2018.10.8-2018.10.12)] 2018 IEEE SmartWorld, Ubiquitous Intelligence & Computing, Advanced & Trusted Computing, Scalable Computing & Communications, Cloud & Big Data Computing, Internet of People and Smart City Innovation (SmartWorld/SCALCOM/UIC/ATC/CBDCom/IOP/SCI) - R-PCNN Method to Rapidly Detect Objects on THz Images in Human Body Security Checks
摘要： Terahertz human body security images have low resolution and a low signal-to-noise ratio. In the traditional method, image segmentation, positioning, and identification are applied to detect objects carried by humans in the THz images. However, it is difficult to satisfy the requirements of detection accuracy and speed with this approach. The current research presents a faster detection framework (R-PCNN) combining the preprocessing and structure optimization of Faster R-CNN. The experiment results show that this method can effectively improve the accuracy and speed of object detection in human body THz images. A detection accuracy of 84.5% can be achieved in dense flow scenes, with an average detection time of less than 20 milliseconds for each image.
关键词： Image enhancement,Terahertz image,Faster R-CNN,Human body security check,Object detection
更新于2025-09-04 15:30:14
-
[IEEE 2018 10th International Conference on Wireless Communications and Signal Processing (WCSP) - Hangzhou, China (2018.10.18-2018.10.20)] 2018 10th International Conference on Wireless Communications and Signal Processing (WCSP) - Achievable Rate of Indoor THz Communication Systems with Finite-Bit ADCs
摘要： In this paper, the achievable rate of the downlink terahertz (THz) communication systems equipped with finite-bit analog-to-digital converters (ADCs) at user sides is investigated. Considering the array of subarray antenna structure, the hybrid precoding with the maximum ratio transmission (MRT) and zero-forcing (ZF) precoding are applied at the baseband. The closed-form expression of the lower bound of the achievable rate is derived when the number of subarray antennas goes to infinity. It is shown that the coarse quantization distortion cannot be ignored in large antenna subarray regime. On the other hand, the rate loss caused by the phase uncertainties can be negligible in large subarray antenna regime. Overall, the impact of quantized receivers on the performance of indoor THz communication systems is characterized.
关键词： finite-bit ADCs,hybrid precoding,Terahertz communication,phase uncertainties,achievable rate
更新于2025-09-04 15:30:14
-
190 GHz high power input frequency doubler based on Schottky diodes and AlN substrate
摘要： This paper presents the design and development of a 190 GHz Schottky-diode frequency doubler (×2 multiplier) which can handle up to 260 mW input power. In order to increase the power handling capability, a modeling approach incorporating computer-aided design (CAD) load-pull techniques to characterize the diode performance is proposed. By the use of this approach, e?ects of several critical diode parameters on the power handling issue are quantitatively investigated and based on the analysis, a discrete diode chip is designed for the doubler. To ensure rapid heat sink in the doubler circuitry, low cost aluminum nitride ceramic (AlN) is selected as the dielectric material of the circuit substrate, which has signi?cantly better thermal conductivity compared with currently widely-used fused quartz. The doubler circuitry is based on a balanced con?guration, which brings a merit of avoiding the use of a ?lter for the input and output signal isolation. The doubler circuit is optimized by co-simulation using ANSYS’s HFSS and Keysight’s ADS. The measurements show that the doubler can handle up to 260 mW input power with a power conversion e?ciency of nearly 8%, resulting in 20 mW output power at 193 GHz.
关键词： high power,AlN substrate,Schottky diodes,CAD load-pull,terahertz multiplier
更新于2025-09-04 15:30:14
-
[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Compact Room-Temperature 510-560 GHz Frequency Tripler with 30-mW Output Power
摘要： We report on a compact high-power 510-560 GHz GaAs Schottky diode based frequency tripler with enhanced power handling capabilities, showing a world-record measured peak power of 30 mW, at room-temperature, when pumped with 350-400 mW. This corresponds to a ten times better performance than previously reported sources in this frequency range. The increase in power handling capabilities is achieved by using an improved epitaxial structure together with an on-chip power combined topology that allows to combine several multiplying structures onto a single chip. The chip also exhibits a state-of-the- art conversion efficiency of 8-9% without any correction for the losses in fixtures/transitions used for the tests.
关键词： Schottky diodes,frequency multipliers,submillimeter-wave technology,terahertz technology.,Submillimeter-wave sources
更新于2025-09-04 15:30:14
-
[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - A Real-Time Non-Destructive Water Status Monitoring System at Terahertz Band
摘要： A novel water content monitoring system of a grapevine based on the reflectivity measurement on the plant trunk at the terahertz band is presented. In order to simulate different outdoor conditions, mainly temperature and lighting, the whole setup, which includes the grapevine and the measurement system, has been settled inside a growth chamber. Fluctuations of lighting conditions, temperature and irrigation have been correlated with variations of the signal power reflected on the trunk using both time domain broadband measurements and, frequency domain narrowband magnitude and phase measurements. The innovative setup enables the achievement of more reliable and accurate results when external conditions vary. Finally, the results have been contrasted, with high level of correlation, with long-established techniques using a dendrometer and a humidity probe.
关键词： xylem water content,reflectometry,dielectric constant,terahertz radiation
更新于2025-09-04 15:30:14
-
Design and numerical analysis of highly birefringent single mode fiber in THz regime
摘要： A novel kind of porous core microstructure optical fiber is proposed in this paper. In order to create flexibility of the fiber only ring air hole is used for the cladding region. Finite Element Method (FEM) based Comsol v4.2 software is used to investigate the guiding characteristics of the proposed fiber. The optimum design parameter shows an ultrahigh birefringence of 0.051, low effective material loss of 0.07 cm?1 and low bending loss of 1.13 × 10?13 dB/cm at 1.2 THz. Moreover, the proposed fiber offers very low dispersion of 1.2 ± 0.32 ps/THz/cm over a wide range of frequency from 1.1 THz to 1.9 THz. Other important guiding characteristics such as confinement loss, effective area and single mode propagation are also discussed in detail. This structure may be a good choice in different remarkable terahertz applications.
关键词： Dispersion,Birefringence,Terahertz waveguide,Effective material loss
更新于2025-09-04 15:30:14
-
Selective trapping of micro-particles on terahertz metamaterial with macro gesture manipulation
摘要： To improve the sensitivity of detecting micro-particles, we propose new designs of terahertz metamaterial devices. These devices use microstructures to support the metal layer of metamaterial and thus can trap micro-particles at sensitive positions. We present two methods of selectively trapping micro-particles on such devices. One is to trap the micro-particles at the openings of split-ring-resonators (SRR), and the other is to trap them inside the SRR. Both methods use simple thumb gestures to control the movement of micro-particles. The methods can capture particles over a large surface area with time efficiency and low cost. Single particle trapped at each trapping site was achievable; the trapping rate was 64% using the first method, and 71% using the second. As a result, the resonant frequency before and after the micro-particles were trapped shifted 23 GHz for the first method and 71 GHz for the second. This shows great improvement as compared to earlier report of 15% trapping rate and 10 GHz resonant frequency shift.
关键词： micro-particles,terahertz metamaterial,selective trapping,resonant frequency shift,macro gesture manipulation
更新于2025-09-04 15:30:14