Aguilar-Merino Patricia, Álvarez-Pérez Gonzalo, Taboada-Gutiérrez Javier, Duan Jiahua, Prieto Iván, Álvarez-Prado Luis Manuel, Nikitin Alexey Y, Martín-Sánchez Javier, Alonso-González Pablo
Department of Physics, University of Oviedo, 33006 Oviedo, Spain.
Center of Research on Nanomaterials and Nanotechnology, CINN (CSIC-Universidad de Oviedo), 33940 El Entrego, Spain.
Nanomaterials (Basel). 2021 Jan 7;11(1):120. doi: 10.3390/nano11010120.
Layered materials in which individual atomic layers are bonded by weak van der Waals forces (vdW materials) constitute one of the most prominent platforms for materials research. Particularly, polar vdW crystals, such as hexagonal boron nitride (h-BN), alpha-molybdenum trioxide (α-MoO) or alpha-vanadium pentoxide (α-VO), have received significant attention in nano-optics, since they support phonon polaritons (PhPs)-light coupled to lattice vibrations- with strong electromagnetic confinement and low optical losses. Recently, correlative far- and near-field studies of α-MoO have been demonstrated as an effective strategy to accurately extract the permittivity of this material. Here, we use this accurately characterized and low-loss polaritonic material to sense its local dielectric environment, namely silica (SiO), one of the most widespread substrates in nanotechnology. By studying the propagation of PhPs on α-MoO flakes with different thicknesses laying on SiO substrates via near-field microscopy (s-SNOM), we extract locally the infrared permittivity of SiO. Our work reveals PhPs nanoimaging as a versatile method for the quantitative characterization of the local optical properties of dielectric substrates, crucial for understanding and predicting the response of nanomaterials and for the future scalability of integrated nanophotonic devices.
由弱范德华力键合单个原子层的层状材料（范德华材料）构成了材料研究中最突出的平台之一。特别是，极性范德华晶体，如六方氮化硼（h-BN）、α-三氧化钼（α-MoO₃）或α-五氧化二钒（α-V₂O₅），在纳米光学领域受到了广泛关注，因为它们支持声子极化激元（PhPs）——与晶格振动耦合的光——具有强电磁约束和低光学损耗。最近，α-MoO₃的相关远场和近场研究已被证明是准确提取该材料介电常数的有效策略。在这里，我们使用这种精确表征且低损耗的极化激元材料来感知其局部介电环境，即二氧化硅（SiO₂），它是纳米技术中最广泛使用的衬底之一。通过近场显微镜（s-SNOM）研究PhPs在置于SiO₂衬底上不同厚度的α-MoO₃薄片上的传播，我们局部提取了SiO₂的红外介电常数。我们的工作揭示了PhPs纳米成像作为一种通用方法，用于定量表征介电衬底的局部光学性质，这对于理解和预测纳米材料的响应以及集成纳米光子器件的未来可扩展性至关重要。
