TST, Vol. 14, No. 1, PP. 1-19
(Invited paper) Photo-Excited Silicon-Based Spatial Terahertz Modulators
Yu-Lian He, Yuan-Sheng Wang, and Qi-Ye Wen *
State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Tech-nology of China, Chengdu 611731, China
* Email: qywen@uestc.edu.cn
(Received January 4, 2021)
Abstract: The increasing development of terahertz (THz) technology has led to various potential applications in THz imaging, spectroscopy and communications. These devices capable of actively manipulating the amplitude, phase and fre-quency of THz waves are thus gaining numerous interests. All-optical silicon-based spatial terahertz modulators (STMs), as a simple, cost-effective, and reconfigurable technique, are standing the focus of research. Beginning with a fundamental concept of THz radiation, this paper systematically summarized the modulation mechanism and theoretical model for this kind of STM, reviewed the recent advancements in THz functional devices implemented by this optical method and yet, discussed the performance-improved measures with an emphasis on the reflection reduction. Despite that, there has been considerable progress in realizing high-performance STMs, and novel design is urgent to realize higher modulation rate and more functionality.
Keywords: Terahertz, All optical devices, Manipulation, Spatial modulator, Silicon devices
doi:
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TST, Vol. 14, No. 1, PP. 20-30
(Invited paper) Nonlinear terahertz effects of gold nanofilms
Peidi Yang 1, Baolong Zhang 2, 3, Jinglong Ma 2, Yutong Li 2, 3, Jungang Miao 1, and Xiaojun Wu 1*
1 School of Electronic and Information Engineering, Beihang University, Beijing 100191, China
2 Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
3 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
*1 Email: xiaojunwu@buaa.edu.cn
(Received March 26, 2021)
Abstract: Nonlinear interaction between strong-field terahertz electromagnetic waves and matters will become one of the next hot research frontiers in nonlinear optics. However, the lack of strong terahertz radiation sources and appropriate nonlinear terahertz materials have impeded its progress. Here we systematically have investigated the strong-field terahertz nonlinear effects of gold (Au) nanofilms on different substrates, including SiO2, high-resistivity Si and SiO2-high-resistivity Si hybrid substrates. The strong-field terahertz waves are emitted from lithium niobate crystals via tilted pulse front technique, and obvious nonlinear transmission responses are observed along with varying the incident field strengths for all the Au samples on the three types of the substrates. The nonlinear behavior is en-hanced when the gold nanofilm thickness increases, which can be qualitatively understood by introducing the quantum tunneling effect and carrier multiplication theory generated at the Au nano-slits under the illumination of the strong-field terahertz pulses. Our demonstrations not only open a new paradigm for nonlinear terahertz investi-gations and future high-speed terahertz devices, but also provide an effective platform for exploring extreme te-rahertz sciences.
Keywords: Nonlinear terahertz effect, Gold nanofilm, Quantum tunneling, Carrier multiplication
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