Reconfigurable nanophotonic components are essential elements in realizing complex and highly integrated photonic circuits. Here we report a novel concept for devices with functionality to dynamically control guided light in the near-visible spectral range, which is illustrated by a reconfigurable and non-volatile ($1\times 2$) switch using an ultracompact active metasurface. The switch is made of two sets of nanorod arrays of ${\mathrm{TiO}}_2$ and antimony trisulfide (${\mathrm{Sb}}_2{\mathrm{S}}_3$), a low-loss phase-change material (PCM), patterned on a silicon nitride waveguide. The metasurface creates an effective multimode interferometer that forms an image of the input mode at the end of the stem waveguide and routes this image toward one of the output ports depending on the phase of PCM nanorods. Remarkably, our metasurface-based $1\times 2$ switch enjoys an ultracompact coupling length of 5.5 μm and a record high bandwidth (22.6 THz) compared to other PCM-based switches. Furthermore, our device exhibits low losses in the near-visible region ($\sim 1\mathrm{dB}$) and low cross talk ($-11.24\mathrm{dB}$) over a wide bandwidth (22.6 THz). Our proposed device paves the way toward realizing compact and efficient waveguide routers and switches for applications in quantum computing, neuromorphic photonic networking, and biomedical sensing and optogenetics.

中文翻译：

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基于可重构超表面的 1 × 2 波导开关

可重构纳米光子元件是实现复杂和高度集成的光子电路的基本要素。在这里，我们报告了一种具有动态控制近可见光谱范围内引导光功能的设备的新概念，这通过可重构和非易失性（$1\times 2$) 使用超紧凑活性超表面进行切换。开关由两组纳米棒阵列组成${\mathrm{二氧化钛}}_2$ 和三硫化锑（${锑}_2{\mathrm{秒}}_3$)，一种低损耗相变材料 (PCM)，在氮化硅波导上形成图案。超表面创建了一个有效的多模干涉仪，它在茎波导的末端形成输入模式的图像，并根据 PCM 纳米棒的相位将该图像路由到输出端口之一。值得注意的是，我们基于超表面的$1\times 2$与其他基于 PCM 的开关相比，该开关具有 5.5 μm 的超紧凑耦合长度和创纪录的高带宽 (22.6 THz)。此外，我们的设备在近可见光区域表现出低损耗（$～1\mathrm{D\; b}$) 和低串扰 ($-11.24\mathrm{D\; b}$) 在很宽的带宽 (22.6 THz) 上。我们提出的设备为实现紧凑高效的波导路由器和开关铺平了道路，这些路由器和开关适用于量子计算、神经形态光子网络、生物医学传感和光遗传学。