International Journal of Terahertz Science and Technology
Vol.13, No.2, June 2020. PP.41-72(3)
date2020-06-30 21:23:59 Click No.163

TST, Vol. 13, No. 2, PP. 41-50

(Invited paper) Novel materials in terahertz functional devices

Fei Fan *, Sheng-Jiang Chang
Institute of Modern Optics, Nankai University, Tianjin 300350, China
* Email:
fanfei@nankai.edu.cn

(Received February 26, 2020)

Abstract: Terahertz (THz) science and technology have been developed rapidly over the past decade due to its superiority in security, communication, imaging, and spectroscopy. In order to manipulate THz waves efficiently, many THz functional materials and devices have been proposed. Metasurfaces with subwavelength elements arranged in a periodic or quasi-periodic manner have been widely investigated. The amplitude, phase and polarization state can be controlled flexibly by designing the geometry. In this paper, several typical THz electromagnetic functional materials will be introduced, magnetic-optical semiconductors, nanoparticle liquid crystal, 3D graphene foam, carbon nanotubes, etc. These electromagnetic functional materials show unique functions for THz active modulation, polarization conversion, one-way transmission, and perfect absorption. Combined with these new materials, we designed and fabricated a series of THz metasurface device to enhance or expand the functions of these functional materials. Meanwhile, the introduction of functional materials brings THz metasurfaces into the active properties. The combination of these artificial micro-structures and electromagnetic functional materials bring new development for active or multifunctional THz devices.

Keywords: Terahertz devices, Nanomaterials, Magneto-optical materials, Liquid crystals

doi:

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TST, Vol. 13, No. 2, PP. 51-60

(Invited paper) Channel estimation for intelligent reflecting surface aided multi-user MISO terahertz system

Wenjie Chen, Zhi Chen *, Xinying Ma
University of Electronic Science and Technology of China, Chengdu, 611731, China
* Email:
chenzhi@uestc.edu.cn

(Received Jun 17, 2020)

Abstract: Intelligent reflecting surface (IRS) is considered as a promising application in terahertz (THz) communications since it is able to enhance the THz communication with no additional power consumptions. In this letter, we consider the channel estimation problem for an IRS-aided THz multi-user multi-input single-output (MISO) system with lens antenna array. The main challenge of the problem is that we need to estimate multiple channels and some of the channels are cascaded. To deal with the problem, we propose a two-stage channel estimation scheme, where we set different IRS modes to estimate different channels for each stage. In stage 1, we set the IRS to an absorbing mode and estimate the channel without IRS. Removing the influence of the prior estimated channel, in stage 2, we estimate the channel with IRS by setting the IRS to a perfect reflecting mode. And we decompose the total channel estimation problem into a series of independent problems, where we estimate each independent channel component with a least square method.

Keywords: Intelligent reflecting surface (IRS), Terahertz (THz) communication, channel estimation

doi:

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TST, Vol. 13, No. 2, PP. 61-72

(Invited paper) High performance terahertz quantum cascade lasers

Y.Y. Li 1, 2, J. Q. Liu 2*, 3 , F.Q. Liu 1, 2, 3 and Z. G. Wang 2, 3
1 Division of Quantum Materials and Devices, Beijing Academy of Quantum Information Sciences, Beijing 100193, China
2 Key Lab. Of Semiconductor Materials Science, Institute of Semiconductor, Chinese Academy of Sciences, Beijing 100083, China
3 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China
*2 Email:
jqliu@semi.ac.cn

(Received May 21, 2020)

Abstract: Terahertz region is the electromagnetic gap between the infrared optoelectronics and the high frequency electronics, which is of broad prospects in applications. The application requirements drive the rapid development in Terahertz technologies including sources, detectors and systems. In the last two decades, quantum cascade laser has made great progress as one of the most promising terahertz sources. In this paper, we present the development of terahertz quantum cascade lasers in our group.

Keywords: Terahertz, Quantum cascade lasers, Distributed feedback, Beam pattern

doi:

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