共查询到17条相似文献,搜索用时 156 毫秒
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为了有效地对太赫兹波进行增强和连续控制,提出一种通过外部空间干扰调制太赫兹波的空间分布对太赫兹波进行增强和连续控制的方法。通过理论计算对比了未放置和放置空心金属波导的太赫兹波的空间分布,并研究了通过外部空间干扰改变太赫兹波传播路径对太赫兹波空间分布的影响。研究表明,采用改变空心金属波导和激光拉丝相对位置的方法,可以得到连续调控的太赫兹波的空间分布,并且太赫兹波空间分布的最强点能量强度增强了近5.9倍,可为宽带太赫兹波的连续调控提供参考。 相似文献
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为实现太赫兹介质波导与金属波导之间模式的转换,设计了一种低损耗、高耦合效率的锥形波导耦合器。通过有限时域差分法(FDTD)对该结构的传输效率进行了仿真优化。仿真结果表明:锥形波导耦合器在170~220 GHz频段,其基模的传输损耗极低;在190~200 GHz频段,其TM基模的传输损耗接近无。该功能器件可以用于集成太赫兹芯片的耦合。 相似文献
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基于平行板波导的双槽谐振腔的特性研究 总被引:2,自引:2,他引:0
为使在太赫兹横电波模式下基于平行板波导的对称的双矩形谐振腔结构在滤波、传感等方面有更好的应用,在理论上使用有限元方法对该结构在太赫兹横电波模式下进行了理论上的模拟仿真,并使用时域太赫兹波谱系统在实验上对其理论仿真结果进行了验证。理论和实验均表明在太赫兹横电波模式下基于平行板波导的对称的双矩形谐振腔结构,对谐振频率的选择以及谐振频率Q值的大小均与两平行板的板间距有关,即随着板间距的增大,谐振频点均出现了红移,红移的速率为136GHz/mm,并且其Q值也随着板间距的增大而变大。此结果对太赫兹横电波模式下基于平行板波导的对称的双矩形谐振腔结构在滤波、传感等方面的应用提供了参数上的依据。 相似文献
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针对地面与飞行器之间通信“黑障”问题,采用垂直极化的太赫兹波实现了地面与飞行器的通信。利用放电装置产生等离子体来模拟飞行器表面的等离子体鞘套,使用全光纤耦合式太赫兹时域光谱仪产生0~1 THz的太赫兹波,从实验的角度研究了垂直极化太赫兹波在不同电子密度的均匀非磁化等离子体中的传输特性。实验结果表明:电子密度越大,垂直极化太赫兹在等离子体中的传播速度越快;随着电子密度的增大,衰减会越小。所进行的研究为实现地面与飞行器之间的通信互联提供了重要的实验参考。 相似文献
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太赫兹波兼具穿透性强、使用安全性高、定向性好、带宽高等技术特性,在国防、深空通信、远程成像、安全检查和医疗诊断等领域具有重大应用前景。基于慢波结构的电真空器件是在太赫兹频段产生瓦级功率输出,同时实现太赫兹辐射源小型化和经济化最具潜力的一种解决方式。慢波结构作为此类电真空器件的核心零件,其物理设计及制造水平将直接影响器件的带宽和增益,因此,从适合工作在太赫兹频段的慢波结构类型、加工精度与表面质量要求,以及制备工艺3个方面出发,对慢波结构的微细加工技术研究现状进行综述,重点分析太赫兹频段慢波结构的关键制造技术水平及应用现状,并探讨其在发展过程中需要面临的挑战和仍需注重解决的问题,希望能为后续高频器件研究工作的推进提供参考。 相似文献
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V. B. Anzin S. P. Lebedev G. A. Komandin O. E. Porodinkov I. E. Spektor 《Instruments and Experimental Techniques》2012,55(1):149-150
A spectrum analyzer of terahertz radiation pulses has been designed for spectroscopic studies of condensed media, gases, and
plasmas. The operating frequency range is 0.05–6.00 THz, the frequency resolution is 0.5 cm−1, and the aperture is 40 mm. 相似文献
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提出了一种适用于太赫兹频段、长距离传输的阶梯式宽带传输线.将2个基片集成波导(substrate integrated waveguide,SIW)分别置于一个矩形波导两端并分别呈直角转接,整个结构组成一级阶梯形状以实现波导口的空间位置平移.通过在矩形波导两端使用耦合窗的方法完成空气与基片介质之间无模式转换的转接.所提... 相似文献
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V. V. Gerasimov B. A. Knyazev P. D. Rudych V. S. Cherkassky 《Instruments and Experimental Techniques》2007,50(4):524-529
Plane-parallel dielectric and semiconductor windows, beam splitters and radiation absorbers, as well as reflecting metal surfaces,
are important components used in experiments with monochromatic terahertz radiation. The wavelengths of this radiation are
longer than the wavelengths of visible light; therefore, multibeam interference becomes important in relatively transparent
components with a thickness of the order of 1 mm, which is typical for optical systems. This interference causes the characteristics
of optical components and detectors to be dependent on the wavelength. It has been found that bolometric power meters with
a crystal used as an absorber of terahertz radiation and pyroelectric detectors with a germanium entrance window demonstrate
individual periodic variations in sensitivity under variations in the wavelength. Basic characteristics of the windows and
beam splitters manufactured from germanium, polypropylene, and Dacron (the materials that are of the greatest interest for
terahertz-band spectroscopy) are calculated in the wave band 30–300 μm. The phase shift of s- and p-polarized terahertz waves reflected from metal surfaces are calculated as functions of the wavelength and the angle of incidence.
Using the Fresenel formulas for processing experimental data on the reflection coefficient of terahertz radiation incident
onto a K8 glass specimen, it is shown that, in the terahertz frequency band, this coefficient is equal to 16% at normal incidence
and the absorption coefficient is equal to 860 cm−1.
Original Russian Text ? V.V. Gerasimov, B.A. Knyazev, P.D. Rudych, V.S. Cherkassky, 2007, published in Pribory i Tekhnika
Eksperimenta, 2007, No. 4, pp. 103–108. 相似文献
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A compact and rigid terahertz time domain spectroscopy system is presented. The size of the device is 20 mm diameter times 61 mm length with four parabolic-shaped concave mirrors dug in it to effectively focus a terahertz beam on a sample. The device has no chromatic aberration over the whole bandwidth of the beam (0.3-2 THz), and an effective numerical aperture of about 0.45 is achieved, which has a capability to image the structure whose size is almost the same as the wavelength. Frequency resolved images clearly show this performance. We also show that quantitative retrieval of the complex refractive index of the structure as small as twice of the wavelength is possible. 相似文献
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A new type of planetary indexing cam mechanism called type IV is presented. The transmission principle of type IV is discussed.
Based on the principle of formation of conjugate tooth contour, the equations of the cam’s pitch curve are derived. The continuity
and symmetry of the cam’s pitch curve are also analyzed. It can be concluded that: 1) This type has no output institution
so the output precision can be improved; 2) The asymmetrical two-ring structure is used to overcome dead point and its phase
angle is equal to (π − 2π/n); 3) The continuous condition of the cam’s pitch curve is that the average transmission ratio is −n in an intermittent motion period.
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Translated from Chinese Journal of Mechanical Engineering, 2006, 42(2) (in Chinese) 相似文献
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A. N. Agafonov B. O. Volodkin A. K. Kaveev B. A. Knyazev G. I. Kropotov V. S. Pavel’ev V. A. Soifer K. N. Tukmakov E. V. Tsygankova Yu. Yu. Choporova 《Optoelectronics, Instrumentation and Data Processing》2013,49(2):189-195
This paper presents a fabrication technique and results of studies of silicon binary diffractive optical elements (DOEs): a diffractive lens and a 1 : 2 diffractive beam splitter with an aperture diameter of 30 mm for the terahertz spectral range. The elements were fabricated in two versions: with and without an antireflection coating of parylene C. The DOE characteristics were investigated in the beam of the Novosibirsk free electron laser at a wavelength of 141 μm. The results are given of a study of the radiation resistance of the coating, which remained intact upon exposure to an average radiation power density of 4 kW/cm2; the peak power in a 100 ps pulse was almost 8 MW/cm2. Experimental estimates of the diffraction efficiency of the elements coated with the antireflection coating are in good agreement with theoretical estimates. 相似文献
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Xianwu Luo Yao Zhang Junqi Peng Hongyuan Xu Weiping Yu 《Journal of Mechanical Science and Technology》2008,22(10):1971-1976
This research treats the effect of impeller inlet geometry on performance improvement for a boiler feed pump, who is a centrifugal
pump having specific speed of 183 m·m3min−1·min−1 and close type impeller with exit diameter of 450 mm. The hydraulic performance and cavitation performance of the pump have
been tested experimentally. In order to improve the pump, five impellers have been considered by extending the blade leading
edge or applying much larger blade angle at impeller inlet compared with the original impeller. The 3-D turbulent flow inside
those pumps has been analyzed basing on RNG k-ɛ turbulence model and VOF cavitation model. It is noted that the numerical results are fairly good compared with the experiments.
Based on the experimental test and numerical simulation, the following conclusions can be drawn: (1) Impeller inlet geometry
has important influence on performance improvement in the case of centrifugal pump. Favorite effects on performance improvement
have been achieved by both extending the blade leading edge and applying much larger blade angle at impeller inlet; (2) It
is suspected that the extended leading edge have favorite effect for improving hydraulic performance, and the much larger
blade angle at impeller inlet have favorite effect for improving cavitation performance for the test pump; (3) Uniform flow
upstream of impeller inlet is helpful for improving cavitation performance of the pump.
This paper was presented at the 9th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007. 相似文献