Abstract-A Dual-Band Terahertz Absorber with Two Passbands Based on Periodic Patterned Graphene

Ximeng Zhang,  Weiwei Wu,  Chenxin Li, Chang Wang, Yuhong Ma , Zhangbiao Yang,
Guang Sun,  Naichang Yuan

https://www.mdpi.com › pdf

In this paper, a dual-band terahertz absorber with two passbands is proposed. The absorber is composed of periodic patterned graphene arrays on the top of a SiO2 substrate and a frequency selective surface (FSS) on the bottom of the substrate. The simulated results indicate that there are two absorption bands (absorption greater than 90%) ranging from 0.54 to 0.84 THz and 2.13 to 2.29 THz. It is almost transparent to incident waves (transmission greater than 50%) below 0.19 THz and between 1.3 and 1.67 THz with a center frequency of 1.49 THz. The absorber has a good tolerance to the transverse electric (TE) and transverse magnetic (TM) polarized wave oblique incidence, and the transmission rate of the passbands remains greater than 50% within 70 degrees. Moreover, the absorption rate of the absorber can be tuned by the chemical potential of graphene. The structure with absorption and transmission properties has potential applications in filtering, sensing, detecting and antenna stealth.

Abstract-Tunable terahertz band-stop filter based on self-gated graphene monolayers with antidot arrays

Wei Wang, Dongxiao Yang, Zhenhai Qian, Chuanshan Xu, Chang Wang,

https://www.sciencedirect.com/science/article/pii/S0030401818305066

An electrically tunable terahertz band-stop filter, which is composed of self-gated graphene monolayers with antidot arrays, is proposed and numerically investigated in this letter. Simulation results show that a pronounced resonance trough caused by graphene surface plasmons (0, 1) mode is obtained, which can be used to realize terahertz band-stop filtering efficiently. Center frequency of the resonance trough can be dynamically controlled over a broad frequency range from 6.6 to 8.6 terahertz through changing the voltage from 8.5 to 24.9 volt. Besides, the proposed filter is independent on the polarization state of incident terahertz wave as a result of its high azimuthal symmetry. The influences of structural parameters, substrate properties and misalignment of the two perforated graphene monolayers are also taken into account in further investigations for better understanding characteristics of the terahertz filter. Specifically, the proposed filter can be applied for refractive index sensing as well with a high sensitivity larger than 8.2 μ$\mathrm{}$m/RIU, which is potentially valuable for gas detection and so on.

Abstract-6.2-GHz modulated terahertz light detection using fast terahertz quantum well photodetectors

Hua Li, Wen-Jian Wan, Zhi-Yong Tan, Zhang-Long Fu, Hai-Xia Wang, Tao Zhou, Zi-Ping Li, Chang Wang, Xu-Guang Guo, Jun-Cheng Cao

(Submitted on 9 May 2017)

https://arxiv.org/abs/1705.03182

The fast detection of terahertz radiation is of great importance for various applications such as fast imaging, high speed communications, and spectroscopy. Most commercial products capable of sensitively responding the terahertz radiation are thermal detectors, i.e., pyroelectric sensors and bolometers. This class of terahertz detectors is normally characterized by low modulation frequency (dozens or hundreds of Hz). Here we demonstrate the first fast semiconductor-based terahertz quantum well photodetectors by carefully designing the device structure and microwave transmission line for high frequency signal extraction. Modulation response bandwidth of gigahertz level is obtained. As an example, the 6.2-GHz modulated terahertz light emitted from a Fabry-P\'{e}rot terahertz quantum cascade laser is successfully detected using the fast terahertz quantum well photodetector. In addition to the fast terahertz detection, the technique presented in this work can also facilitate the frequency stability or phase noise characterizations for terahertz quantum cascade lasers.

Abstract-20 Mbps wireless communication demonstration using terahertz quantum devices

Li Gu, Zhiyong Tan, Qingzhao Wu,  Chang Wang,  Juncheng Cao, 
http://www.opticsjournal.net/abstract.htm?aid=OJ150729000104w3y6B8

A wireless terahertz (THz) communication link is demonstrated, in which a THz quantum cascade laser and a THz quantum-well photo-detector (QWP) serve as the emitter and receiver, respectively. With the help of the well-matched THz QWP, the optical collection efficiency has greatly been improved. A data signal transmitted over 2.2 m with a low bit error rate (<=1 \times 10-8) and data rate as high as 20 Mbps is achieved, which are almost 1 order of magnitude higher than that previously reported.

Abstract-20 Mbps wireless communication demonstration using terahertz quantum devices

Li Gu, Zhiyong Tan, Qingzhao Wu, Chang Wang, and Juncheng Cao
https://www.osapublishing.org/col/abstract.cfm?URI=col-13-8-081402

A wireless terahertz (THz) communication link is demonstrated, in which a THz quantum cascade laser and a THz quantum-well photo-detector (QWP) serve as the emitter and receiver, respectively. With the help of the well-matched THz QWP, the optical collection efficiency has greatly been improved. A data signal transmitted over 2.2 m with a low bit error rate (≤1×10−8) and data rate as high as 20 Mbps is achieved, which are almost 1 order of magnitude higher than that previously reported.

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