Surface plasmon polaritons (SPPs) are electromagnetic excitations existing at the interface between a metal and a dielectric. SPPs provide a promising path in nanophotonic devices for light manipulation at the micro and nanoscale with applications in optoelectronics, biomedicine, and energy harvesting. Recently, SPPs are extended to unconventional materials like graphene, transparent oxides, superconductors, and topological systems characterized by linearly dispersive electronic bands. In this respect, 3D Dirac and Weyl semimetals offer a promising frontier for infrared (IR) and terahertz (THz) radiation tuning by topologically-protected SPPs. In this work, the THz-IR optical response of platinum ditelluride (PtTe₂) type-II Dirac topological semimetal films grown on Si substrates is investigated. SPPs generated on microscale ribbon arrays of PtTe₂ are detected in the far-field limit, finding an excellent agreement among measurements, theoretical models, and electromagnetic simulation data. The far-field measurements are further supported by near-field IR data which indicate a strong electric field enhancement due to the SPP excitation near the ribbon edges. The present findings indicate that the PtTe₂ ribbon array appears an ideal active layout for geometrically tunable SPPs thus inspiring a new fashion of optically tunable materials in the technologically demanding THz and IR spectrum.

中文翻译：

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PtTe2 II 型狄拉克拓扑半金属中的太赫兹和红外等离激元极化子


表面等离子体激元（SPP）是存在于金属和电介质之间界面处的电磁激发。 SPP 为纳米光子器件在微米和纳米尺度上的光操控提供了一条有前途的道路，并在光电子、生物医学和能量收集方面得到应用。最近，SPP 已扩展到非常规材料，如石墨烯、透明氧化物、超导体和以线性色散电子带为特征的拓扑系统。在这方面，3D 狄拉克和韦尔半金属为通过拓扑保护的 SPP 进行红外 (IR) 和太赫兹 (THz) 辐射调谐提供了一个有前景的前沿领域。在这项工作中，研究了生长在 Si 衬底上的二碲化铂 (PtTe ₂ ) II 型狄拉克拓扑半金属薄膜的太赫兹红外光学响应。在远场极限下检测到在 PtTe ₂ 微型带状阵列上产生的 SPP，发现测量、理论模型和电磁仿真数据之间具有良好的一致性。近场红外数据进一步支持了远场测量，近场红外数据表明由于带边缘附近的 SPP 激励而产生了强电场增强。目前的研究结果表明，PtTe ₂ 带状阵列似乎是几何可调谐 SPP 的理想有源布局，从而激发了技术要求极高的太赫兹和红外光谱中光学可调谐材料的新时尚。