Abstract-Actively tunable bi-functional metamirror in a terahertz band

 

Kun Zhang, Yan Liu, Shixia Li, Feng Xia, Weijin Kong, 

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-46-3-464

In this work, we have proposed an actively tunable bi-functional metamirror based on a bi-layer graphene structure. The metamirror acts as a spin-selective absorber under circularly polarized incidence, which behaves as nearly perfect absorption and reflection for right and left circularly polarized waves, respectively, leading to giant circular dichroism. On the other hand, it is a polarization converter under linearly polarized incidence, which reflects the linearly polarized wave into a left circularly polarized wave. Both the spin-selective absorber and the polarization converter can be actively switched between ON and OFF states, with the working frequency controlled by the voltages applied to graphene. Moreover, the metamirror is insensitive to the incidence angle, which contributes to its application as a stable single-mode spin-selective absorber and polarization converter. This bi-layer graphene structure offers a method to construct actively tunable bi-functional metamirrors, which may achieve potential applications in integrated devices, such as active spin detectors, absorbers, and quarter-wave plates for terahertz waves.

© 2021 Optical Society of America

Abstract-Broadband polarization beam splitter based on subwavelength grating in Terahertz

Yelan Zhang,  Yuyang Cheng,  Kun Zhang, Caiyu Li,  Weijin Kong

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11064/110640J/Broadband-polarization-beam-splitter-based-on-subwavelength-grating-in-Terahertz/10.1117/12.2535633.short?SSO=1

We design a broadband polarization beam splitter (PBS) operating in the terahertz (THz) communication band 0.1THz-1.2THz. The transmittance of the TM mode is larger than 95%, in the meanwhile, the extinction ratio can even reach 49dB. Considering the unavoidable deformation in grating fabrication, we also check the performance of the PBS based on trapeziform grating. Results show that increasing the duty cycle while the slope angle diminishing can effectively increase the TM mode transmittance and the extinction ratio, which can compensate the affection induced by the geometric deformation. This design may achieve some potential applications in THz manipulation system.

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