Seeking new ways to actively control the phase using metasurfaces has gained significant attention in recent years, which is the key to achieve controllable wavefronts under external stimuli. Among various active phase control mechanisms, a mechanical method based on gap tuning, termed as gap‐tuned metasurface here, has shown promise in continuous phase adjustment. However, previous studies face limitations in independent and complete phase control at different gap distances, which is crucial in dual‐function switching applications. In this study, a novel type of gap‐tuned metasurfaces are proposed, which can overcome the above limitations through simultaneously manipulating the Pancharatnam–Berry phase and gap‐induced dynamic phase under circularly polarized incidences. Two exemplary gap‐tuned metasurfaces capable of orbital angular momentum (OAM) switching and focusing‐polarity switching are experimentally demonstrated. Furthermore, the special dynamic phase design also exhibits phase conjugate property similar to the Pancharatnam–Berry phase, making circular polarization handedness an alternative route for dual‐function switching. This method provides a straightforward and effective means for the development of active wavefront control devices.

中文翻译：

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用于双功能切换的间隙调谐超表面中的独立相位控制

近年来，寻求利用超表面主动控制相位的新方法引起了人们的广泛关注，这是在外部刺激下实现可控波前的关键。在各种主动相位控制机制中，基于间隙调整的机械方法（此处称为间隙调整超表面）在连续相位调整方面显示出了前景。然而，之前的研究在不同间隙距离下的独立和完整的相位控制方面面临着局限性，这在双功能开关应用中至关重要。在这项研究中，提出了一种新型的间隙调谐超表面，它可以通过在圆偏振入射下同时操纵Pancharatnam-Berry相位和间隙诱导的动态相位来克服上述限制。实验证明了两个能够进行轨道角动量（OAM）切换和聚焦极性切换的示例性间隙调谐超表面。此外，特殊的动态相位设计还表现出类似于Pancharatnam-Berry相位的相位共轭特性，使圆偏振旋性成为双功能切换的替代途径。该方法为主动波前控制器件的开发提供了一种简单有效的手段。