1 厦门理工学院 机械与汽车工程学院，福建 厦门361024
2 精密驱动与传动福建省高校重点实验室(厦门理工学院)，福建 厦门361024
3 厦门市智能制造高端装备研究重点实验室，福建 厦门361024
4 集美大学 海洋装备与机械工程学院，福建 厦门361024
针对现有的雾化装置粒径分散较广及难以生成大量微米级与亚微米级液滴等问题，设计并加工了一种基于声表面波的液滴雾化装置。首先，利用COMSOL仿真软件对声表面波器件的结构建模并进行压电仿真分析，模拟声表面波的振动传播，得到其谐振频率为18.269 MHz。其次，基于声-压电耦合多物理场模拟声波在固-液界面的衍射，以及在液体中的传播过程。最后，加工声表面波雾化实验装置并进行液滴雾化实验，通过调整激励信号频率与输入功率实现了液滴的稳定雾化，对雾化后的液滴粒径分布进行测试。实验结果表明，当输入信号幅值为420 mV，谐振频率为19.259 MHz时，该装置生成大量微米级细小液滴，液滴粒径基本呈三峰分布，主要集中在3 μm、30 μm与500 μm。
声表面波 雾化 声流 有限元仿真 高频 微米级 surface acoustic wave atomization sound flow finite element simulation high frequency micron-scal
Author Affiliations
Abstract
1 School of Electronic Information Engineering, Beihang University, Beijing 100191, China
2 Institute of Modern Optics, Nankai University, Tianjin 300350, China
Terahertz (THz) lenses have numerous applications in imaging and communication systems. Currently, the common THz lenses are still based on the traditional design of a circular convex lens. In this work, we present a method for the design of a 3D-printed multilevel THz lens, taking advantage of the benefits offered by 3D printing technology, including compact size, lightweight construction, and cost-effectiveness. The approach utilizes an inverse design methodology, employing optimization methods to promise accurate performance. To reduce simulation time, we employ the finite-difference time-domain method in cylindrical coordinates for near-field computation and couple it with the Rayleigh–Sommerfeld diffraction theory to address far-field calculations. This technology holds great potential for various applications in the field of THz imaging, sensing, and communications, offering a novel approach to the design and development of functional devices operating in the THz frequency range.
THz lens 3D printing achromatic lens THz communication Chinese Optics Letters
2023, 21(11): 110006
1 北京航空航天大学电子信息工程学院，北京 100191
2 中国科学院物理研究所北京凝聚态物理国家实验室，北京 100190
3 北京航空航天大学网络空间安全学院，北京 100191
4 北京航空航天大学微波感知与安防应用北京市重点实验室，北京 100191
强场太赫兹（THz）时域光谱技术在强场THz科学技术与应用中具有重要作用，材料、物理、化学、生物等领域诸多涉及强场THz与物质强非线性相互作用的研究都离不开强场THz时域光谱技术。然而，受限于高效率、高光束质量、高稳定性、高重复频率强场THz辐射源的性能，强场THz时域非线性光谱技术发展缓慢。针对强场THz非线性光谱技术及其潜在应用中存在的难题与挑战，在商用kHz钛宝石激光器的驱动下，笔者设计并实现了一套基于铌酸锂倾斜波前技术产生强场THz的高度集成化时域光谱系统。在3 mJ激光能量泵浦下，利用该系统在室温下实现了单脉冲能量为6.5 μJ、峰值场强约为350 kV/cm的THz强场产生，该系统具备强场THz非线性光谱测试、THz泵浦‑THz探测、光泵浦‑THz探测、THz发射谱测量等多种超快时间分辨测量功能，是研究强场THz非线性效应的有效实验手段。
超快光学 强场THz辐射 铌酸锂 非线性光谱 泵浦‑探测 中国激光
2023, 50(17): 1714012
北京航空航天大学电子信息工程学院, 北京 100191
太赫兹是电磁频谱上还未被完全开发利用的频段, 但太赫兹谱学成像技术在材料科学和器件测试等方面已展现出重要应用价值。然而受远场衍射极限限制, 该频段难以聚焦于纳米、原子尺度的新材料和微纳器件中, 极大阻碍了太赫兹科学的发展与技术应用。为提高成像分辨率, 使其成为材料科学等交叉领域强大的研究工具, 近年诞生了太赫兹耦合的近场显微技术, 实现了纳米到埃米量级的空间分辨。本文综述了太赫兹耦合的近场显微技术, 包括扫描近场显微镜和扫描隧道显微镜各自的发展历程和应用实例, 并探讨了太赫兹近场显微技术的未来机遇和挑战。
近场显微技术 太赫兹 原子力显微镜 扫描隧道显微镜 near-field microscopy terahertz atomic force microscopy scanning tunneling microscopy
Author Affiliations
Abstract
1 Institute of Modern Optics, Nankai University, Tianjin 300350, China
2 Tianjin Key Laboratory of Micro-Scale Optical Information Science and Technology, Tianjin 300350, China
3 School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
4 State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054, China
5 Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin 300350, China
Dynamic beam steering with unlimited angular range and fast speed remains a challenge in the terahertz gap, which is urgently needed for next-generation target tracking, wireless communications, and imaging applications. Different from metasurface phased arrays with element-level phase control, here we steer the beam by globally engineering the diffraction of two cascaded metagratings during in-plane rotation. Benefiting from large-angle diffraction and flexible on/off control of the diffraction channels, a pair of metagratings with optimized supercells and proper orientation successfully directs the incoming beam towards any arbitrary direction over the transmission half space, with the steering speed improved more than twice that of the small-angle diffractive designs. Single-beam and dual-beam steering within the solid angle of and elevation angle of has been demonstrated with average throughput efficiency of 41.4% at 0.14 THz, which can be generalized to multiple-beam cases. The dual diffraction engineering scheme offers a clear physical picture for beamforming and greatly simplifies the device structure, with additional merits of large aperture and low power consumption.
Photonics Research
2023, 11(1): 44
Author Affiliations
Abstract
1 National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150080, China
2 Nanophotonics and Optoelectronics Research Center, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
3 Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China
Nowadays, multi-functional materials are desperately required for adapting the complex environment, which urges us to take more factors into consideration. Here, we proposed a broadband microwave absorber with multi-functionality such as optically transparent, thermal insulating and soundproof properties. Using indium tin oxide (ITO) based metamaterial, the device can achieve above 90% microwave absorption from 5.6 GHz to 23 GHz (cover X and Ku band). Moreover, with designed vacuum structure inside, the device is thermal insulating and soundproof. These multi- functional advantages give the absorber more flexibility in electromagnetic shielding and stealth application, which can be potentially applied in windows related industry.
光电子快报（英文版）
2021, 17(2): 85
Author Affiliations
Abstract
1 Institute of Modern Optics, Nankai University, Tianjin 300350, China
2 Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Tianjin 300350, China
3 State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
4 Nanophotonics and Optoelectronics Research Center, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
5 e-mail: sjchang@nankai.edu.cn
The nonreciprocal circular dichroism and Faraday rotation effect for terahertz (THz) waves in longitudinally magnetized InSb were investigated by theoretical and experimental studies in the THz regime, which indicated its ability for a THz circularly polarized isolator, THz circular polarizer, tunable polarization converter, and polarization modulator by manipulation of different magnetic fields. Furthermore, we demonstrated the InSb plasmonics based on its magneto-optical effects combined with artificial microstructure. We found the magneto-optical enhancement mechanisms in this magneto-plasmonic structure, achieving broadband near-perfect orthogonal linear polarization conversion modulated by the weak magnetic field in an experiment with an extinction ratio of 33 dB. Moreover, the magneto-optical modulation with an amplitude modulation depth of 95.8% can be achieved by this device under a weak magnetic field of 150 mT. InSb and its magneto-plasmonic device have broad potential for a THz isolator, magneto-optical modulator, and polarization convertor in THz application systems.
Photonics Research
2019, 7(3): 03000325
Author Affiliations
Abstract
1 Tianjin Key Laboratory of Optoelectronic Sensor and Sensing Network Technology, Key Laboratory of Optical Information Science and Technology, Ministry of Education, Institute of Modern Optics, Nankai University, Tianjin 300071, China
2 School of Electronics and Information Engineering, Tianjin Polytechnic University, Tianjin 300387, China
An electromagnetically induced transparency (EIT) in metamaterial resonator with two bright modes and one dark mode at the terahertz (THz) band is numerically and experimentally demonstrated. Different from two kinds of the traditional passive modulations, our design can realize the passive modulation of EIT phenomenon by adding another bright mode resonator. Simulated and experimental results show that the transmission peak varies for incident THz waves with different polarization directions due to its asymmetric structure, which provides a novel way to realize high efficiency switch and modulation.
光电子快报（英文版）
2017, 13(2): 95
江南大学 物联网工程学院，江苏 无锡 214122
传统的稀疏表示跟踪算法直接利用较为简单的灰度特征进行稀疏表示系数计算，易受遮挡、形变等影响。为此，提出一种局部自适应加权算法来增加受遮挡、形变等影响的候选目标与未受遮挡、形变等影响的候选目标之间的区分度。另外，一般稀疏表示算法利用数量较少的目标模板构建过完备字典。无法获得较好的稀疏系数。提出逆稀疏表示算法，利用包含丰富目标特征和背景特征的候选目标构建过完备字典来重构目标模板，相同维度的目标模板条件下可以获得更好的稀疏系数。实验表明，该算法在目标背景差异小或严重遮挡、形变情况下，都能够较好的跟踪目标。
稀疏表示 自适应加权 过完备字典 候选目标 sparse representation adaptive weighting over-complete dictionary candidate target
南开大学现代光学研究所光学信息技术科学教育部重点实验室, 天津 300071
利用太赫兹时域光谱技术(THz-TDS)测试向列相液晶E7 和5CB 在磁场、电场和光场作用下的太赫兹光学性质，较为全面地总结向列相液晶在不同场强下的折射率变化。实验观察到E7和5CB 在磁场下的负磁致折变效应和在电场下的正电致折变效应。磁致折射率变化最大达到-0.087，电致折射率变化最大达到0.051，而光致折变与电致折变的物理本质相同，在7.961 W/cm2的532 nm 激光泵浦下折射率变化最大达到0.015。这些研究结果为液晶材料在太赫兹波段的可调相移器、滤波器和空间光调制器等重要功能器件中的应用打下基础。
物理光学 太赫兹 向列相液晶 折变效应
