CMOS-Compatible Room-Temperature Rectifier Toward Terahertz Radiation Detection

In this paper, we present a new rectifying device, compatible with the technology of CMOS image sensors, suitable for implementing a direct-conversion detector operating at room temperature for operation at up to terahertz frequencies. The rectifying device can be obtained by introducing some simple modifications of the charge-storage well in conventional CMOS integrated circuits, making the proposed solution easy to integrate with the existing imaging systems. The rectifying device is combined with the different elements of the detector, composed of a 3D high-performance antenna and a charge-storage well. In particular, its position just below the edge of the 3D antenna takes maximum advantage of the high electric field concentrated by the antenna itself. In addition, the proposed structure ensures the integrity of the charge-storage well of the detector. In the structure, it is not necessary to use very scaled and costly technological nodes, since the CMOS transistor only provides the necessary integrated readout electronics. On-wafer measurements of RF characteristics of the designed junction are reported and discussed. The overall performances of the entire detector in terms of noise equivalent power (NEP) are evaluated by combining low-frequency measurements of the rectifier with numerical simulations of the 3D antenna and the semiconductor structure at 1 THz, allowing prediction of the achievable NEP.     

Noninvasive Biosignal Detection Radar System Using Circular Polarization

This paper proposes an integrated hypersensitive Doppler radar system through a circular polarization characteristic. Through the idea of a reverse sense of rotation when the reflecting surface is perfectly conducting, it is shown that the detecting property of the system can be effectively improved by using antennas that have a reverse polarization. This bistatic radar system can be used in noninvasively sensing biosignals such as respiration and heart rates with the periodic movement of skin and muscle near the heart. The operating frequency of the system is in the X-band and the radar size is 95 times 50 times 13 mm³.     

通信机房温度检测系统设计

通信机房设备分密集、安全性要求高,要保证通信网络安全、稳定运行,需实时监测机房温度。所以,设计了一款智能化、性价比高的通信机房温度的检测系统。由于传统的温度检测系统测温点少、兼容性和扩展性差的缺点。文中设计主要运用主从分布式通信思想,设计了应用于测量通信机房温度的检测系统。该系统具有结构简单、成本低、可靠性高、测温精确...     

室温CdZnTe核辐射探测器研究进展

简述了CdZnTe材料与探测器的发展、国内外的研究现状及其广泛应用,分析了存在的问题和解决方法,同时介绍了本单位CdZnTe探测器的研发情况,包括探测器的制备工艺及性能测试与分析.制备出了性能优良的阵列像素(3×3)探测器,其57Co 122 keV光谱能量分辨率为23.7%(28.9 keV FWHM),137Cs 662 kev光谱分辨率为17.9%(117.8 keV FWHM).     

Generation of Terahertz Radiation Spectra by Radiation Sources Based on Solid-State Micro- and Nanostructures and Detection of Terahertz Spectra

Principles and mechanisms of generation of terahertz electromagnetic oscillations by generators based on solid-state micro- and nanostructures are discussed. Parameters of experimental models of such devices are given. A theoretical model of terahertz radiation in magnetic metal junctions is presented, and the possibility of varying the frequency of a spin-injection terahertz oscillator is demonstrated. The results of development of methods for examining the spectral characteristics of radiation in the 0.15–80 THz range with a spectral resolution of up to 1.8 GHz are detailed.     

蝶形天线增强的HEMT室温太赫兹探测器

介绍了一种基于GaN/AlGaN高电子迁移率晶体管(HEMT)的高速、高灵敏度室温太赫兹探测器。在太赫兹波辐射下,HEMT源漏端产生直流光电流,并能被栅压灵敏地调控。探测器中新颖的蝶形天线设计使接收到的太赫兹电场得到显著增强,提高了探测器的响应度。通过测量探测器对不同偏振方向的太赫兹光的响应,有效验证了蝶形天线对太赫兹电场的增强作用。室温下,探测器的等效噪声功率约为5×10-10W/Hz21,平均响应度达42mA/W。实验结果表明,光电流的产生与二维电子气沟道的场效应特性和入射太赫兹波电场在电子沟道中的分布密切相关。自混频理论能很好地描述实验结果。     

Heat Induced Damage Detection by Terahertz (THz) Radiation

Terahertz (THz) and sub-terahertz imaging and spectroscopy are becoming increasingly popular nondestructive evaluation techniques for damage detection and characterization of materials. THz radiation is being used for inspecting ceramic foam tiles used in TPS (Thermal Protection System), thick polymer composites and polymer tiles that are not good conductors of ultrasonic waves. Capability of THz electromagnetic waves in detecting heat induced damage in porous materials is investigated in this paper. Porous pumice stone blocks are subjected to long time heat exposures to produce heat induced damage in the block. The dielectric properties extracted from THz TDS (Time Domain Spectroscopy) measurements are compared for different levels of heat exposure. Experimental results show noticeable and consistent change in dielectric properties with increasing levels of heat exposure, well before its melting point.     

Remote Detection of Concealed Radioactive Materials by Using Focused Powerful Terahertz Radiation

This review paper summarizes the results of studies of a novel concept of the remote detection of concealed radioactive materials by using focused high-power terahertz (THz) radiation. The concept is based on the known fact that the ambient electron density in air is low (one to three free electrons per cubic centimeter). These electrons can serve as seed electrons from which an avalanche breakdown in strong electromagnetic fields starts. When a powerful THz radiation is focused in a small spot, the breakdown-prone volume can be much smaller than a cubic centimeter. So, the probability of having some free electrons in this volume and, hence, the probability of breakdown are low in the absence of additional sources of air ionization. However, in the vicinity of radioactive materials (10–20 m), the electron density can be higher, and, hence, there are always some seed free electrons from which the avalanche ionization will start. Thus, the breakdown rate in this case can be close to 100 %. Realization of this concept requires studies of various physical and technical issues. First, it is necessary to develop a high-power source of (sub-) THz radiation whose power, frequency, and pulse duration are sufficient for realizing this goal. Second, it is necessary to analyze numerous issues important for realizing this concept. Among these issues are (a) enhancement of the ionization level of air molecules in the presence of hidden radioactive materials, (b) estimating the minimum detectable mass of radioactive material, (c) formation of breakdown-prone volumes in focused THz wave beams, and (d) effect of atmospheric conditions on the propagation and focusing of THz wave beams and on the optimal location of the breakdown-prone volume between a container with hidden radioactive material and a THz antenna. The results of these studies are described below.     

海洋上空云多角度偏振辐射阈值检测方法研究

云是海洋遥感的一项重要研究内容,云检测精度对于海洋上空云微物理特性的反演和海洋水体观测具有重要意义.以高分五号卫星搭载的大气气溶胶多角度偏振探测仪(Directional polarimetric camera,DPC)在轨成像数据为研究对象,提出了一种基于多角度偏振辐射信息的海洋上空云检测方法.首先用耀光角判别法区分...     

Invited Review Article: Current State of Research on Biological Effects of Terahertz Radiation

Terahertz (THz) imaging and sensing technologies are increasingly being used in a host of medical, military, and security applications. For example, THz systems are now being tested at international airports for security screening purposes, at major medical centers for cancer and burn diagnosis, and at border patrol checkpoints for identification of concealed explosives, drugs, and weapons. Recent advances in THz applications have stimulated renewed interest regarding the biological effects associated with this frequency range. Biological effects studies are a valuable type of basic science research because they serve to enhance our fundamental understanding of the mechanisms that govern THz interactions with biological systems. Such studies are also important because they often times lay the foundation for the development of future applications. In addition, from a practical standpoint, THz biological effects research is also necessary for accurate health hazard evaluation, the development of empirically-based safety standards, and for the safe use of THz systems. Given the importance and timeliness of THz bioeffects data, the purpose of this review is twofold. First, to provide readers with a common reference, which contains the necessary background concepts in biophysics and THz technology, that are required to both conduct and evaluate THz biological research. Second, to provide a critical review of the scientific literature.     

可调谐极化不敏感太赫兹吸收器的设计

太赫兹吸收器广泛应用于军事装备及传感仪器等研究领域,因此,提出了一种四重对称结构的极化不敏感太赫兹超材料吸收器,并通过改变结构尺寸以及电流分布分析了该结构的吸收机理及影响因素.实验结果表明,该吸收器的谐振频率处于太赫兹频段且吸收率可达到99.98％.为了扩大该太赫兹吸收器的应用范围,进一步提出了两种频率可调的极化不敏感...     

Plasmon Excitation and Plasmonic Detection of Terahertz Radiation in the Grating-Gate Field-Effect-Transistor Structures

Physics of plasma oscillations and basic principles of plasmonic detection of terahertz radiation in the grating-gate transistor structures with two-dimensional electron channels are considered. It is shown that the grating-gate-transistor plasmonic detectors can be efficiently coupled to terahertz radiation. Plasmonic detection response considerably increases if the electron density in the grating-gate transistor structure is spatially modulated.     

Photoconductive Emission and Detection of Terahertz Pulsed Radiation Using Semiconductors and Semiconductor Devices

Recent studies on the techniques and development of photoconductive (PC) semiconductor devices for efficient generation and detection of terahertz (THz) pulsed radiation are reported. Firstly, the optimization of PC antenna design is discussed. The PC detection of THz pulsed radiation using low-temperature grown GaAs with 1.55-μm wavelength probe is then described. Finally, the enhancement of THz radiation from InSb by using a coupling lens and magnetic field is investigated. These results reveal valuable insights on the design of an efficient, compact, and cost-effective THz time-domain spectroscopy system based on 1.55-μm fs laser sources.     

室温红外探测薄膜电阻温度系数测试技术

薄膜电阻温度系数的准确测定对红外探测薄膜材料的研究有着十分重要的意义.研究了薄膜电阻温度系数实时测试技术,重点考虑微弱信号放大和噪声有效抑制,实现了微小间隔下对温度和电阻同时采集,以及数据的精确处理.采用该测试系统准确地测试出几种常用红外探测薄膜材料的电阻温度系数.     

太赫兹辐射源的研究进展

太赫兹技术在物理、化学等基础研究学科,以及安全检查、空间通信等应用学科都具有重要的研究价值和应用前景,而太赫兹辐射源正是太赫兹技术发展的关键部分.概述了基于激光光学技术、真空电子技术和超快激光技术产生太赫兹辐射的常用方法和主要特点,以及目前的研究状况,并对这各种太赫兹波辐射源的发展方向进行了展望.     

太赫兹辐射产生技术进展

分别就光学技术和电子学技术产生太赫兹波的方法,介绍其产生原理、研发现状和最新进展,重点介绍了光电导、光整流、参量振荡器和太赫兹量子级联激光器.     

High Power,Room Temperature Terahertz Emitters Based on Dopant Transitions in 6H-Silicon Carbide

Electrically pumped high power terahertz(THz) emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz(20 meV and 50 meV) that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively deep binding energies of the nitrogen donors, above 100 meV, and the high thermal conductivity of the SiC substrates, the THz output power and operating temperature were significantly higher than previous dopant based emitters.With peak applied currents of a few amperes, and a top surface area of 1 mm2, the device emitted up to 0.5 mW at liquid nitrogen temperature(77 K), and tens of microwatts up to 333 K. This result is the highest temperature of THz emission reported from impuritybased emitters.     

High Power,Room Temperature Terahertz Emitters Based on Dopant Transitions in 6H-Silicon Carbide

Electrically pumped high power terahertz (THz) emitters that operated above room temperature in a pulse mode were fabricated from nitrogen-doped n-type 6H-SiC. The emission spectra had peaks centered on 5 THz and 12 THz (20 meV and 50 meV) that were attributed to radiative transitions of excitons bound to nitrogen donor impurities. Due to the relatively deep binding energies of the nitrogen donors, above 100 meV, and the high thermal conductivity of the SiC substrates, the THz output power and operating temperature were significantly higher than previous dopant based emitters. With peak applied currents of a few amperes, and a top surface area of 1 mm2, the device emitted up to 0.5 mW at liquid nitrogen temperature (77 K), and tens of microwatts up to 333 K. This result is the highest temperature of THz emission reported from impuritybased emitters.     

Manipulation of Terahertz Radiation Using Vanadium Dioxide

Vanadium dioxide(VO2) is a phase transition material which undergoes a reversible metal-insulator transition(MIT) when triggered by thermal, photo, electrical, and even stress. The huge conduction change of VO2 renders it a promising material for terahertz(THz) manipulation. In this paper, some interesting works concerning the growth and characteristics of the VO2 film are selectively reviewed. A switching of THz radiation by photo-driven VO2 film is demonstrated. Experiments indicate an ultrafast optical switching to THz transmission within 8 picoseconds, and a switching ratio reaches to over 80% during a wide frequency range from 0.3 THz to 2.5 THz.     

Enhanced Plasma Wave Detection of Terahertz Radiation Using Multiple High Electron-Mobility Transistors Connected in Series

We report on enhanced room-temperature detection of terahertz radiation by several connected field-effect transistors. For this enhanced nonresonant detection, we have designed, fabricated, and tested plasmonic structures consisting of multiple InGaAs/GaAs pseudomorphic high electron-mobility transistors connected in series. Results show a 1.63-THz response that is directly proportional to the number of detecting transistors biased by a direct drain current at the same gate-to-source bias voltages. The responsivity in the saturation regime was found to be 170 V/W with the noise equivalent power in the range of ${hbox{10}}^{-7}~{hbox{W/Hz}}^{0.5}$ . The experimental data are in agreement with the detection mechanism based on the rectification of overdamped plasma waves excited by terahertz radiation in the transistor channel.