Department of Electrical Engineering, Stanford University, Stanford, CA 94305.
Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2022 Mar 22;119(12):e2122085119. doi: 10.1073/pnas.2122085119. Epub 2022 Mar 16.
Control over symmetry breaking in three-dimensional electromagnetic systems offers a pathway to tailoring their optical activity. We introduce fractured Pancharatnam–Berry-phase metasurface systems, in which a full-waveplate geometric phase metasurface is fractured into two half-waveplate-based metasurfaces and actively configured using shear displacement. Local relative rotations between stacked half-nanowaveplates within the metasurface system are transduced by shear displacement, leading to dynamic modulation of their collective geometric phase properties. We apply this concept to pairs of periodic Pancharatnam–Berry-phase metasurfaces and experimentally show that these systems support arbitrary and reconfigurable broadband circular birefringence response. High-speed circular birefringence modulation is demonstrated with modest shearing speeds, indicating the potential for these concepts to dynamically control polarization states with fast temporal responses. We anticipate that fractured geometric phase metasurface systems will serve as a nanophotonic platform that leverages systems-level symmetry breaking to enable active electromagnetic wave control.
控制三维电磁系统中的对称破缺为定制其光学活性提供了一种途径。我们引入了断裂的潘查拉特纳姆-贝里相位超表面系统，其中全波片几何相位超表面被断裂成两个基于半波片的超表面，并使用剪切位移进行主动配置。超表面系统中堆叠的半纳米波片之间的局部相对旋转通过剪切位移进行转换，从而导致它们的集体几何相位特性的动态调制。我们将这一概念应用于一对周期性的潘查拉特纳姆-贝里相位超表面，并通过实验表明，这些系统支持任意和可重构的宽带圆双折射响应。通过适度的剪切速度实现了高速圆双折射调制，表明这些概念具有快速的时间响应动态控制偏振态的潜力。我们预计，断裂的几何相位超表面系统将成为一个纳米光子平台，利用系统级的对称破缺来实现对电磁波的主动控制。
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