共查询到19条相似文献,搜索用时 62 毫秒
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采用激光直写技术在100 μm厚的Si衬底上制备了全介质光栅结构, 利用近红外光抽运-太赫兹探测(near infrared pump-Terahertz probe)技术对该全介质光栅在THz波段的光谱响应及其光调控特性进行了测试, 最后结合电磁仿真结果, 对米谐振(Mie resonance)的形成机理和光调控机理进行了解释并对调控光作用下全介质光栅的电导率数值进行了估算. 研究结果表明: 在光栅与THz偏振垂直的情况下, 该全介质光栅在0-1.0 THz范围内有3个典型的米谐振峰且谐振模式各不相同; 随着调控光功率的增加, 3个谐振峰的谐振强度出现了不同程度的减弱, 其中第一个谐振峰的光调控幅度达到50%以上, 调控光作用下米谐振强度的减弱是由于光生载流子对入射THz波的吸收和散射导致了介质光栅内部感生电磁场减弱引起的. 上述工作对全介质超材料在THz波段的共振特性研究和相关光调控器件的研制具有重要参考价值. 相似文献
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研究了一种基于聚合物太赫兹光纤的太赫兹光纤布喇格光栅.通过二氧化碳激光器或紫外激光器点对点加工聚合物太赫兹光纤,实现聚合物太赫兹光纤直径的周期性调制,从而实现太赫兹光纤布喇格光栅的周期性折射率调制.基于有限元方法和光纤布喇格光栅相关理论,考虑反射峰波长、反射率、带宽、光纤长度、光纤直径和光纤直径形状变化程度等因素,研究了太赫兹光纤布喇格光栅的特性.理论模拟表明,反射峰波长和光栅周期存在与传统光学波段光纤布喇格光栅不同的非线性关系. 相似文献
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受衍射极限的限制,传统太赫兹成像分辨率在毫米量级,无法满足目前前沿研究向微纳米尺度发展的主要趋势。高时空分辨率太赫兹成像技术成为当下太赫兹领域最重要的研究热点之一。近场太赫兹成像技术是实验中将太赫兹成像分辨率提升至微纳米量级的重要方法。介绍了近场太赫兹成像技术的基本原理,详述了多种近场太赫兹成像技术的发展历程与技术路线,从时空分辨能力、频谱分辨能力、成像质量、成像信噪比和适用场景等多个角度分析并总结了各种近场太赫兹成像技术的优势和不足。最后,讨论并展望了太赫兹超分辨成像未来的发展趋势。 相似文献
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搭建了双光束激光干涉光刻系统和激光快速扫描系统。利用干涉光刻系统,实现了不同周期、不同深度、大面积的表面规则光栅织构的构筑。利用激光快速扫描器的二维扫描功能,通过控制激光功率和扫描速度,对曝光量和填充线条间距进行了优化。提出了两种双尺度复合织构的制备方法:一种是在激光快速扫描系统中对抗蚀剂表面分别进行x, y方向的扫描光刻,然后在干涉光刻系统中进行双光束干涉光刻;另一种是在激光干涉光刻系统中进行两次曝光,每次曝光的入射角不同。实验结果表明:这两种方法在制备双尺度复合织构方面具有快速、廉价、操作简易等优点。 相似文献
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基于等效介质膜理论及多层减反膜原理设计了用于超宽带太赫兹吸收体的三层微结构光栅,光栅基质采用重掺硼硅材料.用有限时域差分法分析了光栅周期、光栅宽度和深度对太赫兹吸收体反射系数的影响.数值分析结果表明,在低于3THz波段,吸收率高于98%的带宽为1.3THz,吸收率高于95%的带宽达2.1THz.用严格耦合波理论对该三层光栅的高吸收现象进行理论分析,分析结果表明,光栅多级衍射的相互作用减少了入射面的反射率,增大了该吸收体的吸收率.进一步优化三层光栅微结构的参量,在0.6~6THz范围内实现了大于95%的太赫兹吸收.基于光栅结构的吸收体结构简单,易于设计与分析,可以应用于太赫兹成像与探测应用领域. 相似文献
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随着太赫兹技术及其应用的快速发展,各类太赫兹控制器件需求也随之增加,作为太赫兹系统重要器件之一,太赫兹波移相器成为当前研究热点.已有移相器存在着尺寸较大、结构复杂、相移量较小等问题,为克服上述缺陷,提出一种光栅-液晶复合结构太赫兹移相器,该器件结构为石英、石墨烯、液晶盒、光栅结构、石墨烯和石英组成.通过改变石墨烯电极上... 相似文献
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作为试件变形传感元件的云纹光栅的制作是云纹干涉法的关键技术。本文提出了在120~200℃高温下使用的光刻胶光栅模板的制作及在此温度下试件栅的复制工艺,并利用此技术研究了新型微电子封装组件在125~20℃温度载荷下的热变形。实验结果表明:采用该方法可以获得高质量的试件栅,云纹条纹质量好,可用于试件微小区域内热变形的精确测量 相似文献
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优化设计了多种不同孔径和形状的太赫兹波段的亚波长金属孔阵列结构,结合超薄低折射率的聚酰亚胺(PI)薄膜,探索了太赫兹时域光谱技术对超薄低折射率的探测灵敏性。利用飞秒微加工技术制备了一系列亚波长金属孔阵列结构,利用太赫兹时域光谱技术测试了阵列结构的反射波谱,获得了强烈的反射共振现象。然后在亚波长金属孔阵列结构背面叠加PI薄膜,结果表明太赫兹反射峰出现了显著低频移动现象。利用这一现象,实现了低至10 m的PI薄膜的有效探测,说明亚波长金属孔阵列结构在太赫兹传感领域对检测超薄低折射率薄膜材料有极强敏感性。收稿日期:; 修订日期: 相似文献
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通过仿真计算和实验研究了一种基于频率选择表面的双层改进型互补结构太赫兹带通滤波器.对四裂缝互补型电感电容式谐振单元结构进行了改进,可以在提高滤波性能的同时增加单晶石英介质衬底的厚度.利用电磁仿真技术设计并加工了中心频率为0.28 THz的带通滤波器,并利用太赫兹时域光谱仪测试了在0.1—0.6 THz范围内此滤波器的传输频谱特性,实验结果与仿真结果基本一致.结果表明,利用双层改进型互补结构可以设计出对于入射角度不敏感、带外抑制佳、边带陡峭度大、能有效抑制寄生谐振的宽带太赫兹带通滤波器,并降低了加工难度. 相似文献
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A terahertz(THz) broadband polarizer using bilayer subwavelength metal wire-grid structure on both sides of polyimide film is simulated by the finite-difference time-domain method. We analyze the effect of film thickness, material loss, and lateral shift between two metallic gratings on the performance of the THz polarizer. Bilayer wire-grid polarizers are fabricated by a simple way of laser induced and non-electrolytic plating with copper. The THz time-domain spectroscopy measurements show that in 0.2–1.6 THz frequency range, the extinction ratio is better than 45 d B, the average extinction ratio reaches 53 d B, and the transmittance exceeds 67%, which shows great advantage over conventional single wire-grid THz polarizer. 相似文献
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Junjie Zhang Tao Sun Yongda Yan Yingchun Liang Shen Dong 《Applied Physics A: Materials Science & Processing》2009,94(3):593-600
Three-dimensional molecular dynamics simulation of groove fabrication using atomic force microscopy (AFM)-based nanometric
cutting technique is set up, fabrication processes of grooves with two types (line, and folder line) and five folder angles
(0°, 30°, 45°, 60°, 90°) are simulated to investigate the effect of groove geometry on the fabrication process. The results
show that the Normal force, Lateral force, and Resultant forces are almost symmetric with respect to the critical folder angle
of 45°. The best surface quality of fabricated groove can be obtained at the folder angle of 45°. It reveals that the groove
geometry has a significant effect on the groove fabrication process due to the material anisotropy on the atomic scale. 相似文献
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STM studies of the characteristics of the surface fabrication process using chemical and electrical methods 总被引:1,自引:0,他引:1
C. Wang G. Shang X. Qiu C. Bai 《Applied Physics A: Materials Science & Processing》1999,68(2):181-185
2 surface using STM yielded appreciably different results. It is observed that the threshold pulse voltage is lower than that
for graphite at comparable tunneling conditions. The minimum dimension of the as-produced features is appreciably larger than
those on graphite. Both observations indicate higher surface instability for 1TTaS2 as compared with graphite.
Received: 27 March 1998 相似文献
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Existing techniques for the preparation of silica structures from diatom cells include cleaning of frustules through baking at high temperature and oxidant cleaning using concentrated sulfuric acid, hydrogen peroxide, nitric acid, or sodium dodecyl sulfate (SDS)/ethylenediaminetetraacetic acid (EDTA). In this study, sono-Fenton (SF) process was examined to prepare nanoporous silica through cleaning diatom frustules, while preserving their structural features. Single colonies of Cyclotella sp. were cultivated in batch mode f/2-enriched seawater. Combination of Fenton process with ultrasonication was found to be more efficient than the sum of individual processes in the removal of organic compounds from Cyclotella sp. structure. The optimized amounts of operational parameters were determined as suspension pH of 3, diatom cell density of 4.8 × 105 cell mL−1, H2O2 concentration of 60 mM, Fe2+ concentration of 15 mM, ultrasound irradiation power of 400 W and the temperature of 45 °C. The results of energy-dispersive X-ray spectroscopy (EDX) and thermal gravimetry (TG) analyses proved that organic materials covering the cell wall were significantly removed from the frustules through SF process. Scanning electron microscopy (SEM) images showed that after SF treatment, silica nanostructures were produced having uniform pores less than 15 nm in diameter. N2 adsorption–desorption isotherms demonstrated that almost non-porous structure of diatom frustules became mesoporous during removing the organic matrix. Lipids, amino acids, carbohydrates and organic acids or their oxidized products were identified using GC–MS analysis as the main organic compounds released from diatom cells to the solution after SF treatment. Treated frustules exhibited adsorption capability of 91.2 mg/g for Methylene Blue, which was almost 2.5 times higher than that of untreated frustules (34.8 mg/g). 相似文献
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《Current Applied Physics》2019,19(8):954-960
Solution-processed metal oxide semiconductors have superior electron mobility and stability than solution-processed organic semiconductors. However, their fabrication requires a very-high-temperature and long-time annealing process. In this study, we utilized deep ultraviolet (DUV) light to decrease both the temperature and time of the annealing process. High external energy is required to break the organic bonds in a metal oxide film, which is generally supplied by a high-temperature annealing process carried out for a long duration.Alternatively, the required high energy can be supplied more efficiently by irradiating the metal oxide film with DUV light for a shorter duration. In this work, we used DUV light whose peaks at 172 nm instead of the generally used mercury lamp, peaking at 254 and 185 nm. Owing to this difference, thin film transistors (TFTs) could be fabricated on silicon wafers at a lower temperature and shorter duration as compared to the conditions used in previous studies. Various conditions, such as the heating temperature, duration of DUV irradiation, and N2 flow rate, were optimized to control the heating temperature so as to achieve a mobility of 4.44 cm2/V·s and on–off ratio of 2 × 107, which are much higher than those of a transistor annealed at 300 °C for 30 min (mobility, 1.31 cm2/V·s and on–off ratio, 7 × 105). 相似文献
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A.J. ChoudhuryS.A. Barve Joyanti Chutia A.R. PalD. Chowdhury R. KishoreJagannath N. MithalM. Pandey D.S. Patil 《Applied Surface Science》2011,257(9):4211-4218
Polystyrene films are deposited on bell metal substrates using radiofrequency plasma assisted chemical vapor deposition (RF-PACVD) process. The deposition of polystyrene film is carried out at working pressure of 1.6 × 10−1 mbar and in the RF power range of 20-110 W. The hydrophobic and mechanical behaviors of the polystyrene films are studied as a function of RF power. The chemical compositions and surface chemistry of the polystyrene films are investigated using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). It is revealed that enhanced cross-linked chemical structure and higher loss of oxygen by peroxy polystyryl radical with increasing RF power results in the formation of polystyrene films with more hydrophobic and scratch resistance behavior. However, extensive destruction of cross-linked chemical structure due to high energetic ion bombardment tends to decrease the hydrophobic and scratch resistance behavior of the polystyrene film deposited at RF power of 110 W. Atomic force microscopy (AFM) images show quite uniform and crack free surfaces of the polystyrene films having rms roughness in the range of 0.35-0.87 nm. Attempts are made to correlate the characterization results with the parameters that are used for thin film depositions. 相似文献