Controlling the sign of chromatic dispersion in diffractive optics with dielectric metasurfaces
Controlling the sign of chromatic dispersion in diffractive optics with dielectric metasurfaces
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DOI：
10.1364/optica.4.000625
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发表时间：
2017-06-20
期刊：
影响因子：
10.4
通讯作者：
Faraon, Andrei
中科院分区：
文献类型：
--
作者：
Arbabi, Ehsan;Arbabi, Amir;Faraon, Andrei
衍射光栅以与折射棱镜相反的顺序分散彩虹中的光，这种现象被称为负色散。虽然折射色散可以通过材料折射率来控制，但衍射色散基本上是由几何形状决定的干涉效应。在这里，我们展示了这种基本性质可以改变使用介电超表面，我们实验证明了衍射光栅和聚焦镜具有正，零和超负色散。这些光学元件使用由电介质纳米柱组成的反射超表面来实现，该超表面提供对相位及其波长导数的同时控制。此外，作为第一个实际应用，我们展示了一种聚焦镜，与常规衍射元件相比，它的色散降低了五倍，从而使操作带宽增加了近三倍。这个概念挑战了普遍接受的衍射光学器件的色散特性，并扩展了它们的应用和功能。(C) 2017年美国光学学会
Diffraction gratings disperse light in a rainbow of colors with the opposite order than refractive prisms, a phenomenon known as negative dispersion. While refractive dispersion can be controlled via material refractive index, diffractive dispersion is fundamentally an interference effect dictated by geometry. Here we show that this fundamental property can be altered using dielectric metasurfaces, and we experimentally demonstrate diffractive gratings and focusing mirrors with positive, zero, and hyper-negative dispersion. These optical elements are implemented using a reflective metasurface composed of dielectric nano-posts that provide simultaneous control over phase and its wavelength derivative. In addition, as a first practical application, we demonstrate a focusing mirror that exhibits a five-fold reduction in chromatic dispersion, and thus an almost three-times increase in operation bandwidth compared with a regular diffractive element. This concept challenges the generally accepted dispersive properties of diffractive optical devices and extends their applications and functionalities. (C) 2017 Optical Society of America