Abstract-The Enhanced Third Harmonic Superradiation of Smith Purcell Terahertz radiation source

 Sen Gong, Tao Zhao, Shenggang Liu, Zhenhua Wu, Pengfei Hu, Min Hu, Yueheng Cao, Xiaoqiuyan 

Zhang

https://ieeexplore.ieee.org/document/8510515

Here we propose a new method to enhance the third harmonic of superradiant Smith-Purcell. In this paper, the specific designed grating structure enhances the power of the third harmonic by suppressing the second harmonic. Therefore, the higher frequency radiation signal (25 mW, 326 GHz) is generated by the lower energetic electron beam (9 keV)passing through the grating with larger size (0.4 mm), compared with normal superradiation by using PIC simulation. Accordingly, this mechanism is expected to achieve more efficient compact and tunable terahertz radiation sources with higher frequency.

Abstract-Coherent terahertz radiation generated from a square-shaped free-electron beam passing through multiple stacked layers with sub-wavelength holes

Yucong Zhou, Yaxin Zhang, Guili Jiang and Zhenhua Wu

http://iopscience.iop.org/0022-3727/48/34/345102/article

zhangyaxin@uestc.edu.cn

Terahertz Science Cooperative Innovation Center, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China 

This paper presents terahertz (THz) coherent radiation from the interaction between a square-shaped electron beam and guiding wave mode in a multiple stacked layers with sub-wavelength holes structure. The simulated results show that such a guiding wave mode enhances the field intensity in the electron beam channel so that the interaction is more efficient than the electron beam-surface wave interaction in traditional grating and bi-grating structures. This electron-beam-driven THz source provides a way with much simpler fabrication processes and a larger square size electron beam rather than sheet beam. Furthermore, such a source can be integrated to construct a 2D source-array structure, which demonstrates a good opportunity to generate high power THz radiation.

Abstract-Gbps terahertz external modulator based on a composite metamaterial with a double-channel heterostructure

Yaxin Zhang , Shen Qiao , Shixiong Liang , Zhenhua Wu , Ziqiang Yang , Zhihong Feng , Han Sun , Yucong Zhou , Linlin Sun , Zhi Chen , Xianbing Zou , Bo Zhang , Jianhao Hu , Shaoqian Li ,Qin Chen , Ling Li , Gaiqi Xu , Yuncheng Zhao , and Shenggang Liu

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/acs.nanolett.5b00869

Publication Date (Web): April 28, 2015

Copyright © 2015 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b00869

The past few decades have witnessed a substantial increase in terahertz (THz) research. Utilizing THz waves to transmit communication and imaging data has created a high demand for phase and amplitude modulation. However, current active THz devices, including modulators and switches, still cannot meet THz system demands. Double-channel heterostructures, an alternative semiconductor system, can support nano-scale two-dimensional electron gases (2DEGs) with high carrier concentration and mobility and provide a new way to develop active THz devices. In this article, we present a composite metamaterial structure that combines an equivalent collective dipolar array with a double-channel heterostructure to obtain an effective, ultra-fast and all-electronic grid-controlled THz modulator. Electrical control allows for resonant mode conversion between two different dipolar resonances in the active device, which significantly improves the modulation speed and depth. This THz modulator is the first to achieve a 1-GHz modulation speed and 85% modulation depth during real-time dynamic tests. Moreover, a 1.19-rad phase shift was realized. A wireless free-space-modulation THz communication system based on this external THz modulator was tested using 0.2-Gbps eye patterns. Therefore, this active composite metamaterial modulator provides a basis for the development of effective and ultra-fast dynamic devices for THz wireless communication and imaging systems.