Author Affiliations
Abstract
College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
Spatial terahertz wave modulators that can arbitrarily tailor the electromagnetic wavefront are in high demand in nondestructive inspections and high-capacity wireless communications. Here, we propose a liquid crystal integrated metadevice. It modulates the terahertz wave based on the adjustable electromagnetically induced transparency analog when spatially changing the environmental refractive index. The functions of the device can be arbitrarily programmed via photo-reorienting the directors of liquid crystals with a digital micromirror device-based exposing system. The thin liquid crystal layer can be further driven by an electric field, and thus the function can be rapidly switched. Amplitude modulation and the lens effect are demonstrated with modulation depths over 50% at 0.94 THz.
terahertz spatial terahertz wave modulator metasurface Chinese Optics Letters
2023, 21(1): 010002
1 广州铁路职业技术学院 信息工程学院, 广东 广州 510430
2 南京大学 现代工程与应用科学学院, 江苏 南京 210093
液晶作为宽波段外场可调谐材料在太赫兹波段具有显著的应用优势, 有望实现高效、动态的太赫兹波前调控。本文简要综述了近年来南京大学液晶与微纳光学研究组和其他科研团队在基于液晶的太赫兹波前调控器件领域展开的部分研究, 包括基于纯液晶的太赫兹调波器件和基于液晶集成超构表面的太赫兹调波器件两类, 系统阐述了这些器件的动态可调谐、多样化功能的特征以及潜在的应用前景, 并对液晶技术与太赫兹技术相结合的发展趋势进行了展望。
太赫兹技术 液晶器件 超构表面 动态调谐 terahertz technology liquid crystal device metasurface dynamic tunability
Author Affiliations
Abstract
1 College of Electronic and Optical Engineering & College of Microelectronics, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
2 National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
We demonstrate a tunable terahertz (THz) absorber based on an indium tin oxide (ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching. The thickness of the middle dielectric layer is only 60 μm, which makes the absorber very transparent and flexible. The experimental results show that the THz resonant peaks have a high performance near 1 THz. By setting spacers of different thicknesses between the middle layer and the ITO mirror, a new type of tunable THz absorber is proposed. Its absorption peak frequency can be continuously adjusted from 0.92 to 1.04 THz between TE and TM polarization. This transparent THz metamaterial absorber is expected to be widely used in THz imaging, sensing, and biological detection.
tunable terahertz absorber transparent metamaterial flexible metamaterial Chinese Optics Letters
2020, 18(9): 092403
Author Affiliations
Abstract
1 Department of Physics, Capital Normal University, Beijing 100048, China
2 Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China
In this Letter, we propose that the photopatterned liquid crystal (LC) can act as a broadband and efficient terahertz (THz) Bessel vortex beam (BVB) generator. The mechanism lies in the frequency-independent geometric phase modulation induced by the spatially variant LC directors. By adopting large birefringence LCs and optimizing the cell gap, the maximized mode conversion efficiency can be continuously adjusted in broadband. Furthermore, the LC patterns can be designed and fabricated at will, which enables the THz BVBs to carry various topological charges. Such a THz LC BVB generator may facilitate the advanced THz imaging and communication apparatus.
terahertz liquid crystal Bessel vortex beam photopatterning Chinese Optics Letters
2020, 18(8): 080003
