Microfluid-based soft metasurface for tunable optical activity in THz wave

Zhang, Wu, Bingzhi Zhang, Xiaohui Fang, Kejun Cheng, Weiqian Chen, Zihuang Wang, Dou Hong, and Meng Zhang. “Microfluid-based soft metasurface for tunable optical activity in THz wave.” Optics Express 29, no. 6 (2021): 8786-8795.

Abstract

Metasurfaces are usually planar structures and do not possess intrinsic chirality and therefore hardly generate optical activity. Here we realized a tunable optical activity in a terahertz wave through a microfluid-based soft metasurface. The meta-atom is a chiral structured microchannel made of soft polydimethylsiloxane and injected with the liquid metal Galinstan. A microfluid pressure system is bonded to the metasurface to reconfigure all meta-atoms simultaneously. By pumping glycerol liquid into the pressure system, the metasurface is deformed from a planar structure to a three dimensional one, which manifests intrinsic chirality for optical activity realization. By controlling the injected glycerol volume, a polarization rotation from 0°to 14° at 0.19 THz is demonstrated. The soft metasurface with tunable optical activity can be flexibly applied in various applications such as polarization microscopy, bio-detection and material analysis, etc.

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