Varifocal lenses are essential components of dynamic optical systems with applications in photography, mixed reality, and microscopy. Metasurface optics has strong potential for creating tunable flat optics. Existing tunable metalenses, however, typically require microelectromechanical actuators, which cannot be scaled to large area devices, or rely on high voltages to stretch a flexible substrate and achieve a sufficient tuning range. Here, we build a 1 cm aperture varifocal metalens system at 1550 nm wavelength inspired by an Alvarez lens, fabricated using high-throughput stepper photolithography. We demonstrate a nonlinear change in focal length by minimally actuating two cubic phase metasurfaces laterally, with focusing efficiency as high as 57% and a wide focal length change of more than 6 cm ($>200\%$). We also test a lens design at visible wavelength and conduct varifocal zoom imaging with a demonstrated $4\times$ zoom capability without any other optical elements in the imaging path.

中文翻译：

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具有大面积焦距可调金属感镜的变焦变焦成像

可变透镜是动态光学系统的重要组成部分，可应用于摄影，混合现实和显微镜。超表面光学器件具有创建可调平面光学器件的强大潜力。然而，现有的可调谐金属感测器通常需要微机电致动器，其无法缩放至大面积装置，或无法依靠高电压来拉伸柔性基板并获得足够的调谐范围。在这里，我们建立了一个由Alvarez透镜激发的，在1550 nm波长下具有1 cm孔径的可变焦金属系统，该透镜使用高通量步进光刻技术制造。我们通过最小程度地横向激活两个立方相超表面来证明焦距的非线性变化，聚焦效率高达57％，焦距变化范围超过6 cm（$>200％$）。我们还测试了可见光波长下的镜头设计，并进行了变焦变焦成像。$4\times$ 变焦能力，而成像路径中没有任何其他光学元件。