Microstructure Functional Devices—Effectively Manipulate Terahertz Waves

Terahertz （THz） technology promises important applications including imaging, spectroscopy, and communications. However, one of limitations at present for advancing THz applications is the lack of efficient devices to manipulate THz waves. Here, our recent important progresses in THz functional devices based on artificial microstructures, such as photonic crystal, metamaterial, and plasmonic structures, have been reviewed in this paper, involving the THz modulator, isolator, and sensor. These THz microstructure functional devices exhibit great promising potential in THz application systems.     

Low noise wide bandgap SiC based IMPATT diodes at sub-millimeter wave frequencies and at high temperature

We have presented a comparative account of the high frequency prospective as well as noise behaviors of wide-bandgap 4H-SiC and 6H-SiC based on different structures of IMPATT diodes at sub-millimeter-wave frequencies up to 2.18 THz. The computer simulation study establishes the feasibility of the SiC based IMPATT diode as a high power density terahertz source. The most significant feature lies in the noise behavior of the SiC IMPATT diodes. It is noticed that the 6H-SiC DDR diode shows the least noise measure of 26.1 dB as compared to that of other structures. Further, it is noticed that the noise measure of the SiC IMPATT diode is less at a higher operating frequency compared to that at a lower operating frequency.     

Terahertz Wave Polarization Beam Splitter Using Asymmetrical Coupler

This study has proposed and numerically demonstrated a compact terahertz wave polarization beam splitter. The splitter is built by using a asymmetrical directional coupler consisting of a bend waveguide and a slot bend waveguides and achieves a high extinction ratio of 24.88 dB and 16.55 dB for cross and through ports. The optimal coupling region length is found to be 26 μm. By using such a polarization beam splitter, the size of the terahertz wave system could be reduced significantly. The simulation results show that the designed polarization beam splitter can split TEand TM-polarized terahertz wave into different propagation directions with high efficiency over the terahertz wave frequency range from 9.40 THz to 9.65 THz. The device obtained is readily used for a polarization diversity terahertz wave integrated circuit field, particularly for platforms with slot waveguide.     

太赫兹波辐射源的研究进展

电磁波谱中的太赫兹波段拥有许多比传统光源更独特的性质,在生物、材料、安检和通信等领域有着非常重要的研究价值,而高功率和高效率的太赫兹辐射源则是太赫兹技术转化为实际生产力的一个重要因素和前提条件。文章分别从以气体、固体和液体作为激发介质的角度,总结了激光与不同激发介质相互作用产生太赫兹波的研究进展。对气体介质中常用的四波混频、有质动力、切伦科夫和光电流模型的物理机制以及固体介质中的光电导和光整流模型的物理机制进行了详细撰述,并对影响这几种激发介质产生出太赫兹波的因素进行了分析与总结。最后,对液体激发介质产生出太赫兹辐射源的方法进行了展望。     

太赫兹光非对称解复用器中自发辐射噪声特性分析

提出了一个在超短脉冲注入半导体光放大器 (SOA)时 ,在考虑了半导体带间效应以及带内效应 ,包括载流子热效应、谱烧孔效应、双光子吸收效应以及超快非线性折射效应的自发辐射噪声的计算模型。并利用该模型计算了放大自发辐射 (ASE)噪声对太赫兹光非对称解复用器 (TOAD)开关性能的影响。数值结果表明 ,在考虑ASE噪声情况下 ,TOAD的开关窗口的边沿更陡 ,在开关窗口的尾部还会出现明显的小峰。结果还表明 ,在输入为理想孤子脉冲下 ,即使考虑ASE噪声 ,在TOAD处于开的状态时 ,其输出信号的信噪比也大于 2 5dB。     

植物油的太赫兹时域谱分析

利用太赫兹(THz)时域谱技术测量了山茶油、麻油、橄榄油在0.3~1.5 THz范围内的THz波时域谱,使用迭代算法来计算分析三种植物油的折射率、吸收系数等重要的光学参数。结果表明三种植物油的吸收系数在此波段存在显著差异,三种植物油的平均折射率分别为1.458,1.468和1.452,植物油的折射率随着频率的增加而逐渐减小。该研究成果对于太赫兹时域光谱技术应用于不同的植物油成分及质量评价具有重要意义。     

太赫兹通信技术的研究与展望

太赫兹通信是一个极具应用前景的技术,太赫兹波有非常宽的还没分配的频带,并且具有传输速率高、方向性好、安全性高、散射小及穿透性好等许多特性.发展太赫兹通信技术已成为各发达国家研究的热点.该文分析了国内外太赫兹通信的研究情况;以太赫兹通信系统的整体框架,全面地介绍和分析了太赫兹通信的一些关键技术和最新研究成果;同时,对太赫兹的技术发展趋势和应用前景做了展望,提出了太赫兹技术的发展战略.     

Differences of Band Gap Characteristics of Square and Triangular Lattice Photonic Crystals in Terahertz Range

Band gap characteristics of the photonic crystals in terahertz range with square lattice and triangular lattice of GaAs cylinders are comparatively studied by means of plane wave method (PWM). The influence of the radius on the band gap width is analyzed and the critical values where the band gap appears are put forward. The results show that the maximum band gap width of photonic crystal with triangular lattice of GaAs cylinders is much wider than that of photonic crystal with square lattice. The research provides a theoretic basis for the development of t rahertz (THz) devices.     

几种屏蔽布在太赫兹光谱的实验研究

对灰色、砖红色、深浅迷彩色四种屏蔽布的屏蔽性进行了太赫兹光谱实验研究,得到了这几种屏蔽布的屏蔽效能曲线。实验表明,这几种屏蔽布对太赫兹辐射有很好的屏蔽效能,尤其是灰色屏蔽布的屏蔽效能较好,可用于航空航天及军用仪器设备的屏蔽。若将此类屏蔽布应用在太赫兹波段会有较好的屏蔽效果,会给相应的太赫兹辐射侦查探测带来很大的困难。     

太赫兹量子级联激光器

太赫兹技术近年来发展迅速,应用越来越广泛,是当前的热门研究领域。太赫兹量子级联激光器是产生太赫兹辐射的重要器件,对太赫兹量子级联激光器的发展,以及有源区和波导层的设计等进行了详细讨论。