The efficient selective and directional coupling of light to waveguiding circuitry at the nanoscale is one of the key challenges in nanophotonics, as it constitutes a prerequisite for many applications, including information processing, routing, and quantum technologies. Various exotic nanostructures and nanoparticle arrangements have been designed to achieve directional coupling with compact on-chip integration remaining one of the foremost hurdles to realizing many real-world devices. At the same time, selective coupling to one of several neighboring waveguides is much more difficult to achieve and control. To address this challenge, we demonstrate a subwavelength selective coupler integrated in a waveguide network, with selectivity controlled by wavelength, polarization, and angle of incidence. We utilize a Janus source, which is composed of a superposition of electric and magnetic dipoles, supported by a silicon nanocylinder. By placing the nanocylinder between identical single mode silicon waveguides, we successfully achieve selective coupling with a high contrast ratio between the waveguides. The operating wavelength of the Janus dipolar source can be easily tailored, and the coupling efficiency is also shown to be conveniently boosted by the addition of multiple nanocylinders. Our compact approach provides a direct path toward on-chip highly directional nanoscale sources for a plethora of applications, including information routing, metrology, and quantum technologies.

中文翻译：

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用于选择性耦合到硅波导网络的集成 Janus 偶极子源

纳米级光与波导电路的有效选择性和定向耦合是纳米光子学的关键挑战之一，因为它构成了许多应用的先决条件，包括信息处理、路由和量子技术。各种奇特的纳米结构和纳米粒子排列已被设计来实现定向耦合，紧凑的片上集成仍然是实现许多现实世界设备的最重要障碍之一。同时，与几个相邻波导之一的选择性耦合更难实现和控制。为了应对这一挑战，我们展示了一种集成在波导网络中的亚波长选择性耦合器，其选择性由波长、偏振和入射角控制。我们利用 Janus 来源，它由电偶极子和磁偶极子的叠加组成，由硅纳米圆柱支撑。通过将纳米圆柱放置在相同的单模硅波导之间，我们成功地实现了波导之间具有高对比度的选择性耦合。Janus 偶极源的工作波长可以很容易地定制，耦合效率也显示可以通过添加多个纳米圆柱来方便地提高。我们的紧凑型方法为大量应用（包括信息路由、计量学和量子技术）提供了通往片上高度定向纳米级源的直接路径。我们成功地实现了波导之间具有高对比度的选择性耦合。Janus 偶极源的工作波长可以很容易地定制，耦合效率也显示可以通过添加多个纳米圆柱来方便地提高。我们的紧凑型方法为大量应用（包括信息路由、计量学和量子技术）提供了通往片上高度定向纳米级源的直接路径。我们成功地实现了波导之间具有高对比度的选择性耦合。Janus 偶极源的工作波长可以很容易地定制，耦合效率也显示可以通过添加多个纳米圆柱来方便地提高。我们的紧凑型方法为大量应用（包括信息路由、计量学和量子技术）提供了通往片上高度定向纳米级源的直接路径。