Metasurfaces have shown unprecedented capabilities in the manipulation of the light’s wavefront at subwavelength scale, enabling compact functional devices that can outperform conventional bulk components. A device with multiple functionalities is a continuing trend of device miniaturization and system integration. Here, we propose an approach to design a helicity-dependent multi-foci metalens that can independently generate longitudinally (or transversely) multiple focal points under the illumination of left-hand and right-hand circularly polarized terahertz waves. When this metalens is illuminated with linearly polarized terahertz waves, all of the helicity-dependent multiple focal points are observed simultaneously, leading to the multiplexing of helicity-dependent multiple focal spots. A dielectric metasurface consisting of micropillars with different in-plane orientations is utilized to demonstrate these characteristics. This approach for achieving a helicity multiplexed terahertz multi-foci metalens may open an avenue for designing future multifunctional devices.

中文翻译：

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螺旋多重太赫兹多焦点金属

超表面已经显示出在亚波长范围内操纵光波前的空前能力，从而使紧凑的功能性设备能够胜过传统的体积组件。具有多种功能的设备是设备小型化和系统集成的持续趋势。在这里，我们提出一种设计依赖于螺旋度的多焦点金属元素的方法，该方法可以在左旋和右旋圆偏振太赫兹波的照射下独立地纵向（或横向）生成多个焦点。当这种金属元素被线性极化的太赫兹波照射时，会同时观察到所有依赖于螺旋度的多个焦点，从而导致依赖于螺旋度的多个焦点的复用。由具有不同面内方向的微柱组成的介电超表面被用来证明这些特性。用于实现螺旋复用的太赫兹多焦点金属的这种方法可能为设计未来的多功能设备开辟道路。