Resonant optical nanomaterials with a high refractive index, such as silicon, have become key elements for controlling free-space light. Here, we show that silicon nanoparticles can manipulate highly confined guided waves in the form of surface plasmon polaritons (SPPs) on a subwavelength scale. Using electron energy-loss spectroscopy in a transmission electron microscope, we demonstrate that SPPs in ultrathin metal films can be efficiently launched due to the strong coupling between the Mie resonances of the nanoparticle and the SPP modes. We find that the SPP excitation wavelength can be tuned across the entire near-infrared by varying the particle size. For insight into the coupling mechanism, we also measure the electron-beam-induced response of the Mie resonances in isolated silicon nanostructures in a broad size range. Finally, we show that the silicon nanoparticles act as scatterers of the SPPs supported by the film. Our results may pave the way for using high-refractive-index dielectric nanoantennas as compact elements for manipulating highly confined SPPs.

中文翻译：

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硅纳米粒子的等离子体发射和散射

具有高折射率的共振光学纳米材料，如硅，已成为控制自由空间光的关键元素。在这里，我们展示了硅纳米颗粒可以在亚波长尺度上以表面等离子体激元 (SPP) 的形式操纵高度受限的导波。在透射电子显微镜中使用电子能量损失光谱，我们证明了由于纳米粒子的 Mie 共振和 SPP 模式之间的强耦合，可以有效地发射超薄金属膜中的 SPP。我们发现通过改变粒径可以在整个近红外范围内调整 SPP 激发波长。为了深入了解耦合机制，我们还测量了大尺寸范围内孤立的硅纳米结构中 Mie 共振的电子束诱导响应。最后，我们表明，硅纳米颗粒充当由薄膜支撑的 SPP 的散射体。我们的结果可能为使用高折射率介电纳米天线作为操纵高度受限的 SPP 的紧凑元件铺平道路。