Optical elements based on nanomaterials are becoming major avenues to satisfy the technological requirements of compact, lightweight, and tunable elements of the emerging terahertz (THz) field. A new generation of diffractive components integrating specific geometry with additional features (flexibility, stretchability, rotation, and other approaches for tuning properties) extends the functionality of wavefront control. Here, an innovative approach is demonstrated to control the THz wavefront via a layered composition of spiral zone plates (SZPs) with tunable mutual orientation and scaling. As a proof of concept, the SZP is designed using Laguerre‐Gauss mode analysis with further fabrication and experimental characterization of the resultant vortex beams. For each single SZP, a flexible element is proposed based on a thin film of single‐walled carbon nanotubes deposited on a stretchable substrate. Thus, this diffraction element can be tuned not only by rotation (along the azimuthal direction), but also by its stretching (in the radial direction). The spatial tuning of the developed SZPs (spiral zone plates) opens up an efficient, convenient, and highly customizable approach for the manipulation of vortex beams.

中文翻译：

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利用基于单壁碳纳米管薄膜的先进螺旋波带板扩展太赫兹涡旋产生功能

基于纳米材料的光学元件正在成为满足新兴太赫兹（THz）领域紧凑、轻量化和可调谐元件技术要求的主要途径。新一代衍射组件将特定几何形状与附加功能（灵活性、可拉伸性、旋转和其他调整属性的方法）集成在一起，扩展了波前控制的功能。在这里，展示了一种创新方法，通过具有可调相互方向和缩放比例的螺旋波带片（SZP）的分层组合来控制太赫兹波前。作为概念验证，SZP 是使用拉盖尔-高斯模式分析进行设计的，并对所得涡旋光束进行了进一步的制造和实验表征。对于每个单个 SZP，提出了一种基于沉积在可拉伸基板上的单壁碳纳米管薄膜的柔性元件。因此，该衍射元件不仅可以通过旋转（沿方位角方向）进行调谐，还可以通过其拉伸（沿径向方向）进行调谐。所开发的 SZP（螺旋波带片）的空间调谐为涡旋光束的操纵开辟了一种高效、方便且高度可定制的方法。