Plasmonic waveguides based on 2D materials, which enable the formations of guided modes confined around few-layered material, are promising plasmonic platforms for the miniaturization of photonic devices. Nonetheless, such waveguides support modes that are evanescent in the waveguide core with the majority of the fields concentrated around waveguide edges, which are different from those supported by 3D dielectric waveguides where the modal fields are of oscillatory nature and peak at the center. As a result, many photonic devices and functionalities that can be achieved within 3D dielectric waveguides based on total-internal-reflation modes cannot be realized using 2D material-based plasmonic structures. In this work, we propose and demonstrate how to leverage anisotropy in 2D materials to tailor of modal fields supported by 2D material waveguide for the first time. By regulating material absorption of the constituent 2D materials, the modal fields of these 2D modes can be tailored to localize around the waveguide center, which in turn can improve the efficiencies of coupling-based photonic functions using 2D materials, from in-plane multimode-interference couplers to out-of-plane optical radiation. Using natural anisotropic 2D materials such as black phosphorus, these pivotal functions can expand existing device capabilities that are typically achieved in 3D dielectrics but using 2D materials, thus allowing for the implementation of 2D plasmonic circuits with no need to relying on 3D layers.

中文翻译：

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使用各向异性二维材料结构集成光子功能


基于二维材料的等离子体波导能够形成限制在几层材料周围的导模，是用于光子器件小型化的有前途的等离子体平台。尽管如此，此类波导支持在波导芯中消失的模式，大部分场集中在波导边缘周围，这与 3D 介质波导所支持的模式不同，在 3D 介质波导中，模场具有振荡性质并且峰值位于中心。因此，许多可以在基于全内反射模式的 3D 介电波导内实现的光子器件和功能无法使用基于 2D 材料的等离子体结构来实现。在这项工作中，我们首次提出并演示了如何利用二维材料的各向异性来定制二维材料波导支持的模态场。通过调节组成 2D 材料的材料吸收，可以定制这些 2D 模式的模场以定位在波导中心周围，这反过来又可以提高使用 2D 材料的基于耦合的光子功能的效率，从面内多模到平面外光辐射的干涉耦合器。使用黑磷等天然各向异性 2D 材料，这些关键功能可以扩展通常在 3D 电介质中但使用 2D 材料实现的现有器件功能，从而无需依赖 3D 层即可实现 2D 等离子体电路。