Showing posts with label Cheng-Wei Qiu. Show all posts
Showing posts with label Cheng-Wei Qiu. Show all posts

Sunday, June 14, 2020

Abstract-Ghost spintronic THz-emitter-array microscope


Si-Chao Chen, Zheng Feng, Jiang Li, Wei Tan, Liang-Hui Du, Jianwang Cai, Yuncan Ma, Kang He, Haifeng Ding, Zhao-Hui Zhai, Ze-Ren Li, Cheng-Wei Qiu, Xi-Cheng Zhang,  Li-Guo Zhu


https://www.nature.com/articles/s41377-020-0338-4

Terahertz (THz) waves show great potential in nondestructive testing, biodetection and cancer imaging. Despite recent progress in THz wave near-field probes/apertures enabling raster scanning of an object’s surface, an efficient, nonscanning, noninvasive, deep subdiffraction imaging technique remains challenging. Here, we demonstrate THz near-field microscopy using a reconfigurable spintronic THz emitter array (STEA) based on the computational ghost imaging principle. By illuminating an object with the reconfigurable STEA followed by computing the correlation, we can reconstruct an image of the object with deep subdiffraction resolution. By applying an external magnetic field, in-line polarization rotation of the THz wave is realized, making the fused image contrast polarization-free. Time-of-flight (TOF) measurements of coherent THz pulses further enable objects at different distances or depths to be resolved. The demonstrated ghost spintronic THz-emitter-array microscope (GHOSTEAM) is a radically novel imaging tool for THz near-field imaging, opening paradigm-shifting opportunities for nonintrusive label-free bioimaging in a broadband frequency range from 0.1 to 30 THz (namely, 3.3–1000 cm−1).

Wednesday, April 22, 2015

Abstract- An ultrathin terahertz quarter-wave plate using planar babinet-inverted metasurface





An ultrathin terahertz quarter-wave plate using planar babinet-inverted metasurface

Dacheng Wang, Yinghong Gu, Yandong Gong, Cheng-Wei Qiu, and Minghui Hong  »View Author Affiliations
Optics Express, Vol. 23, Issue 9, pp. 11114-11122 (2015)
http://dx.doi.org/10.1364/OE.23.011114

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-9-11114

Optics Express, Vol. 23, Issue 9, pp. 11114-11122 (2015)

View Full Text Article
Enhanced HTML    Acrobat PDF (1191 KB)

Metamaterials promise an exotic approach to artificially manipulate the polarization state of electromagnetic waves and boost the design of polarimetric devices for sensitive detection, imaging and wireless communication. Here, we present the design and experimental demonstration of an ultrathin (0.29λ) terahertz quarter-wave plate based on planar babinet-inverted metasurface. The quarter-wave plate consisting of arrays of asymmetric cross apertures reveals a high transmission of 0.545 with 90 degrees phase delay at 0.870 THz. The calculated ellipticity indicates a high degree of polarization conversion from linear to circular polarization. With respect to different incident polarization angles, left-handed circular polarized light, right-handed circular polarized light and elliptically polarized light can be created by this novel design. An analytical model is applied to describe transmitted amplitude, phase delay and ellipticitiy, which are in good agreement with the measured and simulated results. The planar babinet-inverted metasurface with the analytical model opens up avenues for new functional terahertz devices design.
© 2015 Optical Society of America