Abstract-Investigation of terahertz radiation based on forward and backward wave feedback circuit

Physics of Plasmas

Luanfeng Gao, Yulu Hu, Xiaofang Zhu, Quan Hu, Jianqing Li, Bin Li,

https://aip.scitation.org/doi/10.1063/1.5124493

A forward and backward wave feedback circuit for a vacuum terahertz radiation source is proposed and demonstrated. In the feedback circuit, two bunched electron beams with different velocities interact with two spatial harmonics, respectively. The simulation reveals that the forward wave and the backward wave form a feedback circuit and affect each other through beam-wave interaction. Furthermore, the maximum gain of the forward wave of the feedback circuit is about 12.4 dB higher than the single beam traveling wave tube. When observing the excitation of the backward wave, it is found that the starting current is 44.4% lower than the traditional backward wave oscillator. The forward and backward wave feedback circuit is a promising choice for the watt-level tunable compact terahertz source that can be potentially used in a transmitter for Terahertz radar detection.

Abstract-THz Photonics in Two Dimensional Materials and Metamaterials: Properties, Devices and Prospects

Jinhui Shi,  Zhongjun Li,  David K. Sang,  Yuanjiang Xiang,  Jianqing Li,  Shuang Zhang,  Han Zhang

http://pubs.rsc.org/en/content/articlelanding/2018/tc/c7tc05460b#!divAbstract

Terahertz radiation refers to a broad electromagnetic spectrum range between microwave and infrared waves, which is also known as terahertz gap due to inadequate materials and technologies for its generation and manipulation. Atomically thin two dimensional (2D) materials such as graphene, black phosphorus (BP) and transition metal dichalcogenides (TMDs) provide a powerful platform for manipulating the propagation and detection of terahertz waves. Furthermore, hybrid meta-materials that feature the combination of artificially engineered meta-materials and 2D materials greatly facilitate dynamic modulation or manipulation of THz radiation towards novel terahertz applications. Herein, we review recent progress on 2D materials in the terahertz domain and hybrid metamaterials with engineered functionalities through the incorporation of graphene, TMDs and BPs. The emerging THz devices based on the modulation, nonlinearity, filtering, and Plasmonics of 2D Materials and Metamaterials will be highlighted, and a brief discussion with perspectives and the remaining challenges will be concluded.