Gate-Tunable Conducting Oxide Metasurfaces
Gate-Tunable Conducting Oxide Metasurfaces
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DOI：
10.1021/acs.nanolett.6b00555
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发表时间：
2016-09-01
期刊：
影响因子：
10.8
通讯作者：
Atwater, Harry A.
中科院分区：
文献类型：
--
作者：
Huang, Yao-Wei;Lee, Ho Wai Howard;Atwater, Harry A.
由亚波长人造结构平面阵列组成的超表面有望实现非凡的光操纵。他们已经生产出新颖的超薄光学元件，例如平面透镜、波片、全息表面以及在广泛的电磁频谱范围内的轨道角动量操纵和检测。然而，迄今为止开发的超表面的光学特性不允许在制造后反射或透射波振幅和相位的多功能可调性。从而限制了它们在广泛的应用中的使用。在这里，我们通过实验证明：门可调谐超表面：能够动态电气控制从超表面反射的平面波的相位和幅度。可调谐性来自于将导电氧化物层的复折射率合并到以反射阵列几何形状配置的超表面天线元件中的场效应调制：我们通过施加 2.5 V 栅极偏置来测量 180 度的相移以及类似于反射率 30% 的变化。此外，我们还演示了通过对超表面元件子组进行电控制来实现超过 10 MHz 的调制频率和 +/- 1 阶衍射光束的电切换，这是电可调光束控制相控阵超表面的基本要求。原则上，电门控相位和幅度控制允许单个超表面元件的电寻址，并为成像和传感技术的超薄光学元件的应用开辟了道路，例如可重构轴承转向装置、动态全息图、可调谐超薄透镜、纳米投影仪和纳米级空间光调制器。
Metasurfaces composed of planar arrays of subwavelength artificial structures show promise for extraordinary light manipulation. They have-yielded novel-ultrathin optical components such as flat lenses, wave plates, holographic surfaces, and orbital angular momentum manipulation and detection over a broad range of the electromagnetic spectrum. However, the optical properties of metasurfaces developed to date do not allow for versatile tunability Of reflected or transmitted wave amplitude and phase after their fabrication,. thus limiting their use in a wide range of applications. Here, we experimentally, demonstrate :a gate-tunable metasurface :that enables dynamic electrical control,of the phase and amplitude of the plane wave reflected from the metasurface. Tunability arises from field-effect modulation Of the complex refractive index Of conducting oxide layers incorporated, into metasurface antenna elements which are configured in reflectarray geometry:We measure a phase shift of 180 degrees and similar to 30% change in the reflectance by applying 2.5 V gate bias. Additionally, we demonstrate modulation at-frequencies exceeding 10 MHz and electrical switching of +/- 1 order diffracted beams by electrical control over subgroups of metasurface elements, a basic requirement for electrically tunable beam-steering phased array metasurfaces. In principle, electrically gated phase and amplitude control allows for electrical addressability of individual metasurface elements and opens the path to applications in ultrathin optical components for imaging and sensing technologies, such as reconfigurable bearh steering devices, dynamic holograms, tunable ultrathin lenses, nanoprojectors, and nanoscale spatial light modulators.