We propose a reflective terahertz (THz) metalens with four focal points for polarization detection of THz beams. The metalens is composed of ${{Z}}$-shaped resonators with spatially variant orientations, a reflective gold layer, and a dielectric spacer between them. The polarization states of the focal points include left circular polarization, right circular polarization, an incident polarization state, and a polarization state whose major axis is rotated $\pi /{{4}}$ in comparison with that of the incident polarization. The handedness, ellipticity, and major axis of the polarization state can be determined based on the light intensities of the focal points. The uniqueness of the designed device renders this technique very attractive for applications in compact THz polarization detection and information processing.

中文翻译：

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用于太赫兹偏振检测的多焦点金属。

我们提出了具有四个焦点的反射太赫兹（THz）金属化材料，用于太赫兹光束的偏振检测。金属元由具有空间变化方向的$ {{Z}} $形谐振器，反射金层和它们之间的介电间隔物组成。焦点的极化状态包括左圆极化，右圆极化，入射极化状态和主轴旋转的极化状态$ \ pi / {{4}} $与入射极化相比。可以基于焦点的光强度来确定偏振态的惯用性，椭圆性和主轴。设计设备的独特性使该技术对于紧凑型THz极化检测和信息处理中的应用非常有吸引力。