共查询到20条相似文献,搜索用时 171 毫秒
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《红外与毫米波学报》2018,(6)
为了提高太赫兹辐射强度,设计了带THz扼流圈的偶极天线阵列.模拟结果表明,增加直线阵的阵元数对平均匹配效率影响很小,却能线性增加相干辐射强度.加入THz扼流圈可减小进入到传输线的交流分量,进而减小共振频率的偏移,使平均匹配效率提升了两倍.相比于网格排列的平面阵,交错排列的阵元在垂直方向上具有更小的耦合,THz发射谱更窄.通过使用聚酰亚胺透镜代替硅透镜,可有效提高输入电阻,并将总效率由25%提高到35%. 相似文献
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基于Smith-Purcell(SP)效应,采用粒子模拟的方法探讨了电子束团激发一维介质光子晶体中的SP辐射特性.模拟研究了单个束团激发一维介质圆柱光子晶体产生的SP辐射现象,并对周期束团激发的THz频段的相干SP辐射进行了模拟分析.研究表明,提高介质的相对介电常数和增加光子晶体的层数都可使辐射强度增加,选择合适的参数能够有效地增强THz频段的相干SP辐射强度. 相似文献
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为提高太赫兹(THz)波的产生效率,研究了飞秒激光与GaAs 晶体的相互作用。首先研究了块状GaAs 晶体中泵浦光与THz 波间的相位匹配,结果显示泵浦光的群折射率曲线与THz 波的折射率曲线不存在交点,表明了块状晶体结构中相位失配问题的存在;然后设计了四种不同尺寸的波导结构,根据波导理论计算了波导结构在0.1~6 THz 波段的折射率,并结合波导的吸收和色散参数分析了THz 波在晶体中的最佳传输距离。研究结果表明,GaAs 波导结构能够有效增大泵浦光与THz 波的相位匹配程度,从而提高飞秒激光与晶体耦合过程中THz 波的产生效率。研究为基于飞秒激光与GaAs晶体相互作用的高效THz 产生技术提供了理论依据。 相似文献
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本文设计了一种高集成检波器,其包含贴片天线、匹配电路、肖特基二极管和透镜。在中芯国际130nm工艺下将天线、匹配电路、肖特基二极管集成到一个芯片上,检波器的集成度相比于分离式有了明显的提高。为增强片上天线的方向性,进行了带有空气腔的尼龙透镜的设计和优化。透镜上的空气腔不但提供了组装空间而且减小了透镜体积。通过测试,天线在220 GHz辐射增益为22 dB,其中透镜贡献约为20dB。检波器测试得到的响应率可达到130-150V/W,对应的等效噪声功率(NEP)估算为400-460 。 相似文献
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提出了一种新型石墨烯THz天线,该天线由金属波导和周围多个石墨烯单元构成,相比于传统的金属天线,具有馈电简单、低剖面的特点。由于石墨烯在THz频率具有负的电导率虚部,因此会激发其局域表面等离激元共振。电磁波通过波导口向外辐射过程中,波导和天线单元之间强烈耦合,形成集体的电磁波振荡,由此天线单元之间保持了良好的相位一致性,最终使得远场的增益比单波导口增益增加了6.5dB,波束宽度则减小至21.2°,有效提高了天线的性能。通过改变石墨烯的偏置电压或者掺杂浓度还可以改变其工作频率,形成可调谐的石墨烯THz天线,未来可以应用于THz通信等方面。 相似文献
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用于毫米波焦面成像阵的介质加载波导阵元分析 总被引:1,自引:0,他引:1
分析了有望用于毫米波成像焦面阵的介质加载波导阵元,采用时域有限差分法(FDTD)计算输入特性,优化了输入基本匹配时的结构尺寸参数,计算该结构参数下的阵元与成像透镜衍射场Airy斑的耦合效率并与其它阵元做了比较。 相似文献
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基于周期相位栅格的塔尔博特效应,提出了一种新型的毫米波频段18合1封闭腔全息准光高效功率合成网络。采用了相邻半周期相差仔的特殊周期相位栅格,置于垂直于栅格的零场区域的金属壁封闭了合成网络,解决了辐射损耗和电磁泄漏问题。基于光学标量衍射理论算法仿真的衍射图样与目标场对比得到的适应度函数,以基因算法优化得到相位栅格,并以变宽波导阵透镜物理实现。在37.5 GHz,功率合成网络实物测试的效率为81%,与电磁仿真的89%基本相符。准光功率合成网络可由一维扩展至二维,合成效率与阵元数、阵元间距无关,可实现毫米波及THz频段的大规模数量器件高效功率合成。 相似文献
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M. Sakhno J. Gumenjuk-Sichevska F. Sizov 《Journal of Infrared, Millimeter and Terahertz Waves》2014,35(9):703-719
The development of THz multielement uncooled imagers based on focal plane arrays (FPAs) requires an optimization of the system parameters to achieve a homogeneous sensitivity of the array elements. Results of numerical simulation of the eight-element linear array of planar antennas with detecting elements, on a substrate of finite dimensions are presented. We establish how the substrate thickness h and the relative permittivity ε r influence antenna pattern and antenna-detector matching for each element. We show that the antenna pattern depends on the detector position more than the antenna – detector impedance matching. The gain of array elements, the antenna-detector matching, and the homogeneity of the detector sensitivity can be simultaneously optimized by the proper choice of the substrate thickness h and the relative permittivity ε r . We show that multielement systems with large substrate thickness and high relative permittivity are not suitable for the imaging system implementation. To achieve uniform multielement system sensitivity, substrates with low permittivity (ε r <5) and/or low thickness (h< 60 μm for the Si substrate) should be used. Finally, we investigate the operation of the detector array with optimally chosen substrate parameters together with the focusing lens, and show that the system is able to work as FPA without significant image corruption. 相似文献
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Truong Khang Nguyen Haewook Han Ikmo Park 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(3):333-347
A full-wavelength dipole antenna on a GaAs membrane, covered with a silicon lens to improve the output power of a terahertz
(THz) photomixer, is proposed. A full-wavelength dipole antenna supported by a GaAs membrane structure has been proven to
achieve both high input resistance and high radiation efficiency for improved overall efficiency. However, the antenna has
insufficient directivity. An extended hemispherical lens was introduced in front of the antenna in a non-contact configuration
and coupled to the antenna radiation to achieve high directivity by beam collimation. This approach greatly enhances the antenna
directivity while avoiding an inherent obstacle of the input resistance reduction caused by the high permittivity lens substrate.
The resulting antenna after optimization had a 3818-Ω input resistance and a 71.2% radiation efficiency, corresponding to
approximately 57% total efficiency at the 1.07-THz resonance frequency. The total efficiency of this structure is approximately
6.8 times that of a full-wavelength dipole antenna with the same hemisphere lens size while exhibiting slightly lower directivity. 相似文献
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《Photonics Technology Letters, IEEE》2009,21(13):830-832
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中物院太赫兹自由电子激光(CTFEL)装置是我国第一台基于超导加速器的高重复频率、高平均功率太赫兹自由电子激光装置。CTFEL利用光阴极直流高压电子枪和超导加速器产生约8 MeV电子束在波荡器中产生自发太赫兹(THz)辐射,并在光腔中受激放大获得饱和输出。得益于在0.7~4.2 THz频谱范围内连续可调以及平均功率大于10 W的特性,CTFEL为材料动力学、太赫兹成像、太赫兹生物学等领域提供了独特的研究平台。自2018年开放成为用户装置以来,每年提供不少于1000 h的稳定出光。未来CTFEL将在现有基础上升级成为红外太赫兹自由电子激光装置,实现太赫兹频率全覆盖以及最大功率大于100 W的目标,力争成为世界先进的长波长自由电子激光装置。 相似文献
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Ao Zhiguang Sun Jinhai Cai He Song Guofeng Song Jiakun Song Yuzhi Xu Yun 《半导体学报》2016,37(12):123002-6
Photoconductive antennas (PCAs) based on nanoplasmonic gratings contact electrodes have been proposed to satisfy the demand for high power, efficiency and responsivity terahertz (THz) sources. Reducing the average photo-generated carrier transport path to the photoconductor contact electrodes was previously considered the dominant mechanism to improve PCAs'' power. However, considering the bias in a real device, the electric field between gratings is limited and the role of surface plasmonic resonance (SPR) field enhancement is more important in improving THz radiation. This paper, based on SPR, analyzes the interaction between incident light and substrate in nano cylinder array PCAs and clearly shows that the SPR can enhance the light absorption in the substrate. After the optimization of the structure size, the proposed structure can offer 87% optical transmission into GaAs substrate. Compared with conventional PCAs, the optical transmission into the substrate will increase 5.8 times and the enhancement factor of substrate absorption will reach 13.7 respectively. 相似文献
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A dielectric lens antenna that is a special case of an extended hemispherical dielectric lens and is operated in the diffraction-limited regime is considered. The dielectric lens antenna is fed by a planar antenna that is mounted on the flat side of the dielectric lens antenna, using it as a substrate, and the combination is termed a hybrid antenna. Beam pattern and aperture efficiency measurements were made at millimeter and submillimeter wavelengths as a function of the extension of the hemispherical lens and of lens size. An optimum extension distance for which excellent beam patterns and simultaneously high aperture efficiencies can be achieved is found experimentally and numerically. At 115 GHz the aperture efficiency was measured to be (76±6)% for a diffraction-limited beam with sidelobes below -17 dB. Results for a single hybrid antenna with an integrated superconductor-insulator-superconductor (SIS) detector and a broadband matching structure at submillimeter wavelengths are presented. The hybrid antenna is space efficient in an array due to its high aperture efficiency, and is easily mass produced, thus being well suited for focal plane heterodyne receiver arrays 相似文献
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《Antennas and Propagation, IEEE Transactions on》2008,56(9):2970-2980