Abstract-Terahertz broadband spoof surface plasmon polaritons using high-order mode developed from ultra-compact split-ring grooves

Kai-Da Xu, Ying Jiang Guo, and Xianjin Deng

Fig. 1 Schematic configuration of the proposed THz SSPP unit cell. (a) Slotline with two-side transversal grooves (Structure A). (b) Grounded slotline with two-side transversal grooves (Structure B). (c) Grounded slotline with two-side split-ring grooves (Structure C). The detailed dimensions are D = 20 µm, L2 = 36.2 µm, L3 = 43 µm, W0 = 1.5 µm, W1 = 1 µm, W2 = 220 µm, W3 = 75.9 µm, W4 = 12.5 µm, W5 = 1 µm, and W6 = 1 µm. (d) Dispersion curves of the fundamental and high-order modes of different SSPP unit cells. The inset is the z-component electric field distributions of the first two modes of the Structure C unit cell.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-4-4354

Terahertz (THz) broadband spoof surface plasmon polaritons (SSPPs) using new structure of ultra-compact split-ring grooves are proposed. The high-order mode propagation is highly concentrated around the proposed structure with lower radiation loss implying improved operating bandwidth. More importantly, a size reduction of 83.5% can be realized as compared to the traditional grounded SSPP structure with the same high-order asymptotic frequency. To further verify the proposed idea, a similar structure in microwave regime is designed and measured, where the excitation is easily achieved by directly connecting the microstrip line to the proposed SSPP waveguide. The gradient transition section, such as flaring ground, can be avoided, which decreases the waveguide’s longitudinal and transversal lengths and simplifies the design procedure. The measured results of the microwave prototype illustrate that it has good lowpass filtering performance, in which the reflection coefficient is better than −10 dB up to 13 GHz, with the smallest and worst insertion losses of 0.5 dB and 4.5 dB, respectively. To the best of the authors’ knowledge, this work presents THz high-order broadband SSPP propagation for the first time, having significant potential for plasmonic integrated circuits application at microwave/THz frequencies.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreementhttps://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-4-4354

Abstract-340-GHz 3-D Imaging Radar With 4Tx-16Rx MIMO Array

Binbin Cheng,  Zhenmao Cui, Bin Lu,  Yuliang Qin,  Qiao Liu,  Peng Chen,  Yue He,  Jun Jiang,   Xiaoyang He, Xianjin Deng, Jian Zhang, Liguo Zhu, 

https://ieeexplore.ieee.org/document/8404082/

A standoff 3-D imaging radar for security body scan at 340 GHz has been described. This terahertz imager incorporates a multiple input multiple output (MIMO) array as an electronic beam former in a horizontal dimension and an elliptic cylinder as a focusing reflector in elevation. Frequency-modulated continuous-wave (FMCW) emission with 16-GHz bandwidth caused a 10-mm-range resolution after calibration for nonlinearities of the distorted radar signals. The horizontal MIMO array contains 4 transmitters and 16 receivers (4Tx-16Rx) to generate a 64-Tx/Rx full virtual array corresponding to an antenna size of approximately 128 mm, which caused a horizontal resolution of about 14 mm at a distance of 3 m. FMCW signals were transmitted from the 4-Tx sequentially and focused as narrow beam lines by the elliptic reflector to get a 12-mm vertical resolution at 3 m. A fast-scanning mirror swings in the light path to make these beam lines screen in the vertical direction. A 4-Hz frame rate is now possible for a personal screen with a field of view of 2 m × 0.6 m.

Abstract-Fast Three-Dimensional Image Reconstruction of a Standoff Screening System in the Terahertz Regime

Jingkun Gao   Zhenmao Cui ;  Binbin Cheng,   Yuliang Qin, Xianjin Deng,  Bin Deng,   Xiang Li,  Hongqiang Wang

https://ieeexplore.ieee.org/document/8115312/

Based on a novel prototype terahertz screening system, its ability of fast three-dimensional (3-D) image reconstruction is demonstrated. We first give a brief introduction of the system. Then detailed analyses on signal model, system calibration, the influences of approximations, and the imaging performances are conducted. At last, proof-of-concept experiments are performed and preliminary 2-D and 3-D imaging results are presented. We show that the imaging problem can be resorted to a problem of spectral estimation finally. At this stage on this prototype system, a 180 cm × 90 cm region at 4-m range costs less than 0.1 s for 2-D imaging, 1 s for 3-D imaging and an extra 2 s for mechanical scanning. Faster speeds are on the horizon as hardware and software updates are ongoing. These results show its potential of real-time 3-D imaging for standoff concealed threats detection.