Dynamic metasurface control is a promising yet challenging prospect for next generation optical components. Here, we design and characterize a thermally controllable metasurface lens, with a high-quality-factor (high-Q) resonance working as both the basis of the lensing behavior and method for efficient modulation. Our high-Q lens is constructed via a zone plate architecture comprised of alternating regions with and without resonant character. Non-resonant regions block transmission, while resonant regions—with measured Qs up to ∼1350—transmit only on resonance. By leveraging the thermo-optic effect, we dynamically control the spectral position of the high-Q resonance to achieve wavelength selectivity of the focusing behavior. Due to the sharp spectral linewidth and amplitude variation of the high-Q resonance, thermal tuning can further result in metasurface switching, where the lensing behavior is changed between on and off states. For a device utilizing only moderate Q-factors of ∼350, the resonance's FWHM can be shifted with temperature changes of only 50 °C, and the device can be fully switched off when operating at 100 °C. Our work provides an initial experimental demonstration of dynamic control of a local high-Q wavefront shaping metasurface.

中文翻译：

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热控高 Q 超表面透镜

动态超表面控制对于下一代光学元件来说是一个充满希望但又充满挑战的前景。在这里，我们设计并表征了一种热可控的超表面透镜，其具有高质量因数（高 Q）共振作为透镜行为和有效调制方法的基础。我们的高 Q 透镜是通过波带片架构构建的，该架构由具有和不具有共振特性的交替区域组成。非共振区域阻止传输，而共振区域（测量 Q 值高达 ~1350）仅在共振时传输。通过利用热光效应，我们动态控制高 Q 共振的光谱位置，以实现聚焦行为的波长选择性。由于高 Q 共振的尖锐光谱线宽和振幅变化，热调谐可以进一步导致超表面切换，其中透镜行为在开和关状态之间发生变化。对于仅使用 ~350 的中等 Q 因子的设备，共振的 FWHM 可以随着温度变化仅 50 °C 发生偏移，并且该设备在 100 °C 下运行时可以完全关闭。我们的工作提供了局部高 Q 波前整形超表面动态控制的初步实验演示。