Abstract The purity of an optical vortex beam depends on the spread of its energy among different azimuthal and radial modes, also known as ℓ $\ell $ - and p-modes. The smaller the spread, the higher the vortex purity and more efficient its creation and detection. There are several methods to generate vortex beams with well-defined orbital angular momentum, but only few exist allowing selection of a pure radial mode. These typically consist of many optical elements with rather complex arrangements, including active cavity resonators. Here, we show that it is possible to generate pure vortex beams using a single metasurface plate—called p-plate as it controls radial modes—in combination with a polarizer. We generalize an existing theory of independent phase and amplitude control with birefringent nanopillars considering arbitrary input polarization states. The high purity, sizeable creation efficiency, and impassable compactness make the presented approach a powerful complex amplitude modulation tool for pure vortex generation, even in the case of large topological charges.

中文翻译：

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具有单个超表面的纯涡流生成的任意偏振转换

摘要 光学涡旋光束的纯度取决于其能量在不同方位角和径向模式之间的传播，也称为 ℓ $\ell $ - 和 p 模式。扩散越小，涡流纯度越高，其创建和检测效率越高。有几种方法可以产生具有明确轨道角动量的涡旋光束，但只有少数几种方法允许选择纯径向模式。这些通常由许多排列相当复杂的光学元件组成，包括有源腔谐振器。在这里，我们表明可以使用单个超表面板（称为 p 板，因为它控制径向模式）与偏振器结合产生纯涡旋光束。我们概括了考虑任意输入偏振态的双折射纳米柱的独立相位和幅度控制的现有理论。即使在大拓扑电荷的情况下，高纯度、相当大的创建效率和不可逾越的紧凑性使所提出的方法成为用于纯涡流生成的强大的复杂幅度调制工具。