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中国物理学会期刊

弧度与旋转共同诱导相位调控太赫兹超表面

CSTR: 32037.14.aps.74.20241465

Radian and rotation co-induced phase controlling terahertz metasurfaces

CSTR: 32037.14.aps.74.20241465
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  • 传统编码超表面都是按照几何相位或传输相位理论来实现相位调控的, 然而几何相位具有自旋锁定特性, 传输相位具有单频特性, 限制了利用统一超表面同时调控几何相位和传输相位. 本文提出了一种弧度与旋转共同诱导相位调控超表面, 超表面单元能对左旋圆极化波(LCP波)和右旋圆极化波(RCP波)的交叉极化反射相位进行独立调控, 在1—1.2 THz范围内均满足要求. 通过相位卷积与共享孔径原理, 该超表面可以实现多通道涡旋、聚焦、完美涡旋等功能, 提高了电磁空间的利用率, 在未来太赫兹通信系统中具有广阔的应用前景.

     

    Metasurfaces have the characteristics of simple structure, easy fabrication, easy integration, etc., and can flexibly control electromagnetic waves. They are widely used in terahertz filters, lenses, polarization converters, wavefront adjustment and terahertz imaging and so on. By encoding and arranging unit cells with different amplitudes and phases according to a certain rule, the metasurfaces can achieve various functions such as imaging, focusing, beam splitting, and vortex beam. The reported coding metasurfaces are phase-modulated according to geometric phase or transmission phase theory. However, geometric phase has spin-locking property and transmission phase has single-frequency property, which hinder the applications of a unified metasurface in simultaneously regulating geometric phase and transmission phase.
    To address the above issues, in this work, we propose an radian and rotation co-induced phase modulation metasurface, whose unit cell independently modulates the cross-polarized reflection phases of LCP wave and RCP wave and has a certain bandwidth, which meets therequirement in a frequency region of 1–1.2 THz. Through the principle of phase convolution and shared aperture, the metasurface realizes the vortex beams with a topological charge of ±1, focusing with a focal length of 1500 μm, the deflected vortex beams with a topological charge of ±2, the quasi-perfect vortex beams, and the multichannel vortex beams. The structure has the advantages of simple structure, flexible and convenient regulation, and compact size, which improves the utilization of the electromagnetic space and has a broad application prospect in the future terahertz communication systems.

     

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