十字架型超材料吸波特性及机理研究

设计了一种十字架型电磁超材料吸波体,采用CST studio suite 2009 频域求解器提取S 参数进行仿真研究,并计算了其吸波率,在24.65 THz 和35.25 THz 得到两个吸收峰,吸收率分别为0.83 和0.997。改变材料结构尺寸,在7.3 THz 达到完美吸收,吸收率接近于1。将THz 波段的超材料吸波体结构尺寸放大1000 倍,在GHz 波段同样可以达到完美吸收,说明超材料吸波体可通过对结构尺寸调节改变吸收波段。另外研究了这种吸波体的吸收机理,发现吸收主要在第一层的十字架金属单元层,可用于Bolometer 探测器的设计。     

基于光子带隙的双平板太赫兹传输系统研究

研究了一种利用光子晶体带隙特性工作的双平板太赫兹传输系统,它结合了光子晶体波导传输能量集中、损耗低以及双平板波导低色散和单模传输的优点.具体设计了工作在O.32THz的传输系统,研究结果表明:光子晶体双平板波导不但可以实现单模的高效传输,而且也具有良好的输入输出匹配性能.该设计中,采用矩形波导的输入输出结构在316～360 GHz的带宽内可以获得S11<-10 dB的匹配.而且,和普通双平板波导相比更具有结构紧凑、易于集成等优点,因此具有较高的实用价值.     

基于圆盘加载波导的THz 分布作用振荡器的模拟研究

提出了一种新型的基于圆盘加载波导的THz 分布作用振荡管（Extended-Interaction Oscillator, EIO）,它由圆盘加载波导输入谐振腔、漂移段和输出腔三部分组成。利用2.5 维电磁仿真软件－UNIPIC 对其进行模拟研究。研究表明慢波结构的长度、漂移管的长度和输出管的高度对输出功率和频率产生显著影响。经过最优化设计,在注电压为27.7 kV,电流为20 mA 的条件下,仿真得出其中心频率为730.86 GHz ,峰值功率为442.1 mW 的THz 波。     

Analysis and design of enhanced directivity microstrip antenna at terahertz frequency by using electromagnetic bandgap material

In this paper, an electromagnetic bandgap (EBG) material in the range of 0.5–0.8 THz has been simulated with Arlon AR 600 (ε=6.0) as host material and air‐cylinders as the foreign embedded material. The effective dielectric permittivity of this material has been analyzed at the frequency range of 0.590–0.620 THz. The reduced effective dielectric permittivity substrate of thickness 50 µm has been used to design the microstrip antenna at 600 GHz with a novel approach. This proposed antenna shows an enhanced directivity of 15.1 dBi at 600 GHz frequency. To compare the analysis, the operating frequency has been scaled down by a factor of 100 and various results have been compared by using two different commercially available simulators CST Microwave Studio based on the finite integral technique and Ansoft HFSS based on the finite element method. Copyright © 2010 John Wiley & Sons, Ltd.     

THz辐射的研究和应用新进展

THz频段是一个非常具有科学价值但尚未开发的电磁辐射区域,它的研究涉及物理学、光电子学及材料科学等,它在成像、医学诊断、环境科学、信息通信及基础物理研究领域有着广阔的应用前景和应用价值。当今,获得THz波的方法及THz波的探测研究是THz研究领域的前沿,更是重点。本文综述了THz波的特点、应用领域及发展状况,阐述了THz波的产生方法其探测方法。     

新的太赫兹超高速无线网络媒体访问控制协议

针对现有无线网络媒体访问控制(MAC)协议难以在太赫兹（THz）载频条件下实现10Gbps级别超高速无线接入的问题,提出一种新的太赫兹超高速无线网络MAC协议——MAC-T。MAC-T设计了新的时分多路访问(TDMA)+载波侦听多路访问(CSMA)自适应混合MAC接入机制和一种新的超帧结构,并定义了对应于太赫兹通信的关键参数,从而使最大数据传输速率达到10Gbps以上。理论分析和仿真结果表明：MAC-T协议能够在太赫兹无线网络中正常运行,数据传输速率达到了18.3Gbps,是IEEE 802.15.3c标准定义的最大速率5.78Gbps的2.16倍,数据帧的平均接入时延约为0.0044s,性能相对于IEEE 802.15.3c标准提高了42.1%,从而在MAC协议方面为太赫兹超高速无线网络的研究和应用提供了有力支撑。     

THz plasma wave instability in field effect transistor with electron diffusion current density

The plasma wave instability in rectangle field effect transistors (FETs) is studied with electron diffusion current density by quantum hydrodynamic model in this paper. General dispersion relation including effects of electrical thermal motion, external friction associated with electron scattering effect, electron exchange-correlation contributions and quantum effects were obtained for rectangle FETs. The electron diffusion current density term is considered for further analysis in this paper. It is found that the quantum effects, the electron diffusion current density and electrical thermal motion enhance the radiation power and frequencies. But the electron exchange- correlation effects and the electron scattering effects reduce the radiation power and frequencies. Results showed that a transistor has advantages for the realization of practical terahertz sources.     

Morphological changes in epoxy resin (DGEBA/TETA) exposed to low temperatures

Abstract

Epoxy resin (DGEBA/TETA) is commonly used as an adhesive material. When this material is subjected to low temperatures for an extended period of time, it undergoes changes in inter/intramolecular vibrations which has been probed in this research through a combination of terahertz spectroscopy, differential scanning calorimetry and infrared spectroscopy. Distinctive morphological changes of the virgin material are observed for the exposed material at cold temperature which can be attributed to incomplete reversibility of segmental as well as entire molecular chain mobility.     

Impact of additives and processing on microstructure and dielectric properties of willemite ceramics for LTCC terahertz applications

The paper presents the fabrication procedure, microstructure and dielectric properties of the low temperature cofired ceramics (LTCC) based on Zn₂SiO₄ doped with AlF₃, CaB₄O₇, Li₂TiO₃ and MgTiO₃. The heating microscope studies and differential thermal analysis were used for characterization of the behavior of the green tapes and ceramic samples during heating up to high temperatures. The microstructure and composition were analyzed by scanning electron microscopy, X-ray energy dispersive spectroscopy and XRD method. The dielectric properties were investigated in three frequency regions: 100 Hz–2 MHz, 90–140 GHz and 0.15–3 THz. The developed materials are promising candidates for the LTCC submillimeter wave applications due to a low sintering temperature of 900–980 °C, good compatibility with silver pastes and good dielectric properties – a low dielectric permittivity of 6–6.8, a relatively low dissipation factor of 0.005–0.008 at 1 THz, and a weak temperature dependence of dielectric permittivity.     

基于二维光子晶体的多频段太赫兹波滤波器研究

基于二维光子晶体,提出一种多频段 太赫兹(THz)波滤波器。在光子晶体中引入3条平行的横向波导,通过改变介质柱的半 径或插入半径较小的介质柱在 相邻波导之间构成耦合区域,使特定频率的THz波从中部波导耦合至上、下侧光子晶体波 导并分别从端口2和1输出, 其余的THz波经中部波导从端口3输出,最终达到多频段滤波的效果。利用时域有限差 分法和平面波展开法对所提出 的器件计算和仿真结果显示,频率为f=3.24和3.75THz的THz波分 别从端口1、2和3输出中,传输效率分 别达到95%和99% ,表明本文结构能很好实现多频段滤波效果。