二维范德华材料的双曲声子极化激元（PhPs）具有极高的光场限域能力，能够将中红外光场压缩至低于光学衍射极限的纳米尺度空间内，在中红外光场局域调控和亚波长聚焦方面有巨大的潜力。本项目将以天然双轴范德华晶体氧化钼（α-MoO3）为对象，围绕其中红外波段的双曲PhPs效应，设计并制备基于薄层α-MoO3的光场耦合结构，采用高分辨近场光学成像技术为主要手段，测量α-MoO3及其光场耦合结构的近场光学特性，结合解析理论模型及数值模拟方法，系统地研究研究其光场局域分布与入射光波长和偏振态、结构的几何形状和尺寸，以及离子插层和温度等外部激励的依赖关系和变化规律，进而获得中红外光场的纳米尺度聚焦。最后，我们将把以上研究结果用于探索研究氧化钼PhPs在中红外光学超分辨成像的应用。本项目将为中红外波段的纳米尺度光与物质相互作用的研究及未来中红外纳米光子学器件的设计提供研究基础和技术储备。

The hyperbolic phonon polaritons (PhPs) of two-dimensional van der waals materials can confine the mid-infrared light into the deep sub-diffractional nanoscale, which can pave the way of light manipulating and sub-wavelength focusing in the mid-infrared region. In this proposal, we will focus on the mid-infrared hyperbolic phonon polaritons in a biaxial van der Waals crystal molybdenum oxide (α-MoO3). We aim to systematically study the sub-wavelength manipulation of mid-infrared electromagnetic field localization enabled by the highly-confined hyperbolic PhPs. By utilizing the high-resolution scanning near-field microscopy, in combination with the analytic theory model and numerical simulation, we will systematically study the dependence of the near-filed electromagnetic field distribution of α-MoO3 flake combined with the designed metal nanoantenna, including the incident wavelength and polarization, the geometric shape and size of the nanoantenna. Furthermore, we will study the controlling and tailoring of this near-field optical distribution by intruducing external incentives, such as ion intercalated and temperature. Ultimately, the nano-scale focusing of the mid-infrared electromagnetic field will be obtained. On the basis of the above results, the application of PhPs in mid-infrared optical super-resolution imaging will also be investigated. We strongly believe that the success of this proposal will not only provide further understanding of the nanoscale light-matter interaction in min-infrared region but also pave the way for designing the mid-infrared novel nano-photonics devices.