Due to the ongoing improvement in nanostructuring technology, ultrathin metallic nanofilms have recently gained substantial attention in plasmonics, e.g. as building blocks of metasurfaces. Typically, noble metals such as silver or gold are the materials of choice, due to their excellent optical properties, however they also possess some intrinsic disadvantages. Here, we introduce niobium nanofilms (~10 nm thickness) as an alternate plasmonic platform. We demonstrate functionality by depositing a niobium nanofilm on a plasmonic fiber taper, and observe a dielectric-loaded niobium surface-plasmon excitation for the first time, with a modal attenuation of only 3–4 dB/mm in aqueous environment and a refractive index sensitivity up to 15 μm/RIU if the analyte index exceeds 1.42. We show that the niobium nanofilm possesses bulk optical properties, is continuous, homogenous, and inert against any environmental influence, thus possessing several superior properties compared to noble metal nanofilms. These results demonstrate that ultrathin niobium nanofilms can serve as a new platform for biomedical diagnostics, superconducting photonics, ultrathin metasurfaces or new types of optoelectronic devices.
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机译：由于纳米结构技术的不断改进，超薄金属纳米膜最近在等离激元学中得到了广泛的关注，例如等离子体。作为超表面的基础。通常，贵金属（例如银或金）由于其出色的光学性能而成为首选材料，但是它们也具有一些固有的缺点。在这里，我们介绍铌纳米膜（约10 nm厚）作为替代等离子体平台。我们通过在等离子体纤维锥度上沉积铌纳米膜来演示功能，并首次观察到负载了电介质的铌表面等离子体激元的激发，在水性环境中模态衰减仅为3-4 dB / mm，并且折射率敏感如果分析物指数超过1.42，最高可达15μm/ RIU。我们表明，铌纳米膜具有整体光学性质，是连续的，均质的，并且对任何环境影响均呈惰性，因此与贵金属纳米膜相比具有几种优越的性能。这些结果表明，超薄铌纳米膜可作为生物医学诊断，超导光子，超薄超颖表面或新型光电器件的新平台。
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