Hyperbolic metamaterials comprised of an array of plasmonic nanorods provide a unique platform for designing optical sensors and integrating nonlinear and active nanophotonic functionalities. In this work, the waveguiding properties and mode structure of planar anisotropic metamaterial waveguides are characterized experimentally and theoretically. While ordinary modes are the typical guided modes of the highly anisotropic waveguides, extraordinary modes, below the effective plasma frequency, exist in a hyperbolic metamaterial slab in the form of bulk plasmon‐polaritons, in analogy to planar‐cavity exciton‐polaritons in semiconductors. They may have very low or negative group velocity with high effective refractive indices (up to 10) and have an unusual cut‐off from the high‐frequency side, providing deep‐subwavelength (λ₀/6–λ₀/8 waveguide thickness) single‐mode guiding. These properties, dictated by the hyperbolic anisotropy of the metamaterial, may be tuned by altering the geometrical parameters of the nanorod composite.

中文翻译：

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双曲纳米棒超材料波导中的体等离子体激元-极化子。

由等离子纳米棒阵列构成的双曲线超材料为设计光学传感器以及整合非线性和有源纳米光子功能提供了独特的平台。在这项工作中，实验和理论上表征了平面各向异性超材料波导的波导特性和模结构。普通模式是高各向异性波导的典型引导模式，而低于有效等离子体频率的特殊模式则以体等离激元-极化子的形式存在于双曲线超材料平板中，类似于半导体中的平面腔激子-极化子。它们可能具有非常低的或负的群速度，具有高的有效折射率（高达10），并且在高频侧具有不寻常的截止频率，从而提供了深亚波长（λ₀ / 6- λ ₀ /8波导厚度）单模引导。这些属性（由超材料的双曲各向异性决定）可以通过更改纳米棒复合材料的几何参数来调整。