Nonlinear Terahertz Generation: Chiral and Achiral Meta-Atom Coupling |
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Authors: | Qingwei Wang Xueqian Zhang Quan Xu Xi Feng Yongchang Lu Li Niu Xieyu Chen Eric Plum Jianqiang Gu Quanlong Yang Ming Fang Zhixiang Huang Shuang Zhang Jiaguang Han Weili Zhang |
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Affiliation: | 1. Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, and the Key Laboratory of Optoelectronics Information and Technology, Tianjin University, Tianjin, 300072 P. R. China;2. Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton, SO17 1BJ UK;3. School of Physics and Electronics, Central South University, Changsha, Hunan, 410083 P. R. China;4. Key Laboratory of Intelligent Computing and Signal Processing, Ministry of Education, Anhui University, Hefei, 230039 P. R. China;5. Department of Physics, Faculty of Science, University of Hong Kong, Hong Kong, 999077 P. R. China;6. School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, Oklahoma, 74078 USA |
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Abstract: | Generation and manipulation of terahertz (THz) waves are of vital importance for advancing THz technology. Nonlinear metasurfaces allow effective integration of both processes into a single compact device. However, such existing THz devices commonly rely on utilizing a single meta-atom, which has fixed THz generation properties and thus limits the range of achievable functionalities. Here, it is demonstrate how coupling between different meta-atoms within the unit-cell can be used as a degree of freedom for controlling nonlinear THz generation, where achiral coupling provides full control over the amplitude of the generated THz field, while chiral coupling makes the THz generation sensitive to the handedness of the pump polarization. In particular, chiral coupling allows the realization of multiplexed pump-handedness-selective nonlinear metasurfaces, which is illustrated experimentally by selectively generating THz beams with different orbital angular momentum with a single nonlinear metasurface. This approach provides opportunities for developing various integrated nonlinear THz devices. |
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Keywords: | amplitude tuning broadband terahertz generation coupling nonlinear circular dichroism nonlinear metasurfaces |
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