MoO3异质结中可调控面内双曲声子极化激元的光学特性及应用研究

最新研究表明，三氧化钼晶体中存在面内双曲声子极化激元(HPhPs)。这些特殊的极化激元表现出极低的传播损耗和极强的电磁场限域能力，可显著增强中红外波段的光与物质相互作用，有丰富的光学和热学应用潜力，例如，亚波长成像、偏振器件、高集成波导、热辐射控制和化学传感。然而，面内HPhPs受限于材料的本征晶格振动，较难进行动态调节，不利于实现可调控的中红外微纳光学器件。针对这个问题，本项目提出构建两种特殊异质结构：石墨烯/三氧化钼、相变材料/三氧化钼。这两种异质结构中，三氧化钼HPhPs的传播特性可被石墨烯外加门电压或者相变材料的晶态-非晶态转化所改变，从而可以实现主动可调谐的HPhPs传播。在机理研究的基础上，我们将面向实际应用，研究基于面内各向异性HPhPs的可快速调控、超薄、高性能的中红外光偏振器件，重点研究偏振消光比、响应速度等重要器件指标，项目成果有望助力于新型红外微纳光学器件的发展。

It has been recently demonstrated that molybdenum trioxide crystals can support in-plane hyperbolic phonon polaritons （HPhPs）. These polaritons exhibit low propagation loss and strong electromagnetic field confinement. They could enhance light-matter interaction at the mid-infrared frequencies for rich optical and thermal applications, such as sub-wavelength imaging, polarization devices, highly integrated waveguides, thermal radiation control, and chemical sensing. However, in-plane HPhPs are limited by the intrinsic lattice vibration, which cannot be tuned dynamically and thus are not suitable for realizing tunable mid-infrared nanophotonic devices. To overcome this problem, this project aims to create two special heterostructures: graphene / molybdenum trioxide, phase change materials / molybdenum trioxide. In these two heterostructures, the propagation of HPhPs can be controlled by adjusting the graphene gate voltage or by controlling the crystalline-amorphous transition of phase change materials. Consequently, active tuning of the HPhPs can be achieved. Our project will first study the propagation properties and the tuning mechanism of HPhPs in the heterostructures. Second, we will focus on practical applications and aim to achieve tunable, ultra-thin, high-performance mid-infrared polarization devices based on in-plane HPhPs. We will also investigate the device performance, including the minimal device thickness, the polarization-dependent extinction ratio, and the tuning speed. The results will be useful for the development of novel mid-infrared nanophotonic devices.