Metasurfaces have shown extraordinary light-manipulation abilities, however, most of them deal with free-space waves. It is highly desirable to develop a guided wave-driven metasurface which can extract the in-plane guided modes in the waveguide and mold it into the desired out-of-plane free-space modes. In this paper, an all-dielectric guided wave-driven metasurface, composed of an array of silicon meta-atoms on top of a silicon nitride waveguide, is proposed and simulatively demonstrated. When directly driven by fundamental transverse electric (TE₀₀) and fundamental transverse magnetic (TM₀₀) guided modes at operation wavelength 1.55 µm, the guided wave-driven metasurface converts them into y-polarized and x-polarized free-space light, respectively, and focuses them at different focal points, with polarization extinction ratio over 27 dB, thus simultaneously realizing triple functions of coupling guided modes to free-space waves, bifocal metalens and polarization demultiplexing. Our work offers an alternate way to control light across photonic integrated devices and free-space platforms.

中文翻译：

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导波驱动超表面的双焦聚焦和偏振解复用

超表面显示出非凡的光操纵能力，然而，它们中的大多数处理自由空间波。非常需要开发一种导波驱动的超表面，它可以提取波导中的平面内导模并将其塑造成所需的平面外自由空间模式。在本文中，提出并模拟演示了一种全介电导波驱动的超表面，由氮化硅波导顶部的硅超原子阵列组成。当由基波横电（TE ₀₀）和基波横磁（TM ₀₀）直接驱动时) 工作波长为 1.55 µm 的导模，导波驱动的超表面将它们分别转换为 y 偏振和 x 偏振的自由空间光，并将它们聚焦在不同的焦点上，偏振消光比超过 27 dB，因此同时实现将导模耦合到自由空间波、双焦元透镜和偏振解复用的三重功能。我们的工作提供了另一种控制光子集成设备和自由空间平台光的方法。