The Pancharatnam–Berry geometric phase has attracted great interest due to the elegant phase control strategy via geometric transformation of optical elements. The commonly used geometric phase is associated with circular polarization states. Here, we show that by exploiting the geometric phase associated with the two elliptical eigen-polarization states in a racemic metallic helix array, exotic features including full range phase modulation for linear polarization states, diverse polarization conversion, and full complex amplitude modulation can be obtained with rotation of the helices. As a proof of concept, several devices for implementing polarization conversion, vortex beam generating, and lateral dual focusing are built with a racemic helix array in the microwave regime. The calculated and experimental results validate our proposals, which can stimulate various advanced metadevices.

中文翻译：

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基于外消旋螺旋阵列中的几何相位控制相位、极化和幅度

由于通过光学元件的几何变换的优雅相位控制策略，Pancharatnam-Berry 几何相位引起了极大的兴趣。常用的几何相位与圆偏振态有关。在这里，我们表明，通过利用与外消旋金属螺旋阵列中的两个椭圆本征偏振态相关的几何相位，可以获得包括线性偏振态的全范围相位调制、不同偏振转换和全复振幅调制在内的奇异特征。随着螺旋的旋转。作为概念证明，用于实现偏振转换、涡旋光束生成和横向双聚焦的几个设备在微波范围内使用外消旋螺旋阵列构建。计算和实验结果验证了我们的建议，