Abstract-Triple-Band Terahertz Perfect Light Absorber Using the Strong Interaction of Two Metallic Resonators

Ben-Xin Wang, Chao Tang, Qingshan Niu, Yuanhao He, Fuwei Pi,  Xiaoyi Wang,

https://link.springer.com/article/10.1007/s11664-020-08337-x

An approach to realize a multiple-band perfect light absorber is demonstrated using a simple metamaterial design featuring a composite metallic structure consisting of a closed ring and a rectangular patch atop a metallic substrate separated by an insulator. Three narrow-band and discrete resonance peaks with nearly 100% absorption rates are obtained. The first absorption peak is due to the dipole resonance of the closed ring, while the last two absorption peaks are caused by the coupling effect of the closed ring and rectangular patch. The field distribution of the three absorption peaks is given to provide additional evidence. Unlike traditional multiple-band light absorbers that eliminate (or avoid) the interaction between the metallic array structures, our design is based on the mode coupling of the composite structure. This method can obviously reduce the number of metallic resonators, simplify the structure design and reduce fabrication costs.

Abstract-Probe position correction based on overlapped object wavefront cross-correlation for continuous-wave terahertz ptychography

Lu Rong, Chao Tang, Dayong Wang, Bing Li, Fangrui Tan, Yunxin Wang, and Xiaoyu Shi

Fig. 1 A schematic representation of the proposed algorithm. If the initial probe position is determined, the following probe positions are successively estimated by Eqs. (2) – (5).

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-2-938

Continuous-wave terahertz ptychography is a promising large field-of-view lensless terahertz phase imaging method. Inaccurate probe positions would severely degrade the reconstruction quality, as compared to other spectral bands. In this paper, we propose a probe position correction method based on cross-correlation registration on overlapped regions of the object wavefront for terahertz ptychography. The translation errors could be minimized in the order of 0.01 pixels. The simulation results suggest good computational efficiency, correction, and reconstruction accuracy. We perform continuous-wave terahertz ptychography on a cicada’s forewing. The subcosta and the first radius vein are distinguished after position correction. The probe position distribution reveals that the tilt angle between the object plane and the recording plane is 0.26°.

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