太赫兹波段高性能VO2人工材料的动态电磁特性研究

In order to improve the modulation depth and speed for the metamaterial based terahertz (THz) modulators, the vanadium dioxide (VO2) has been explored as a key functional material for the devices, which exhibits dramatic and abrupt changes in the optical and electrical characteristics across the insulator-metal phase transition. Based on our previous works, we will make further investigations about the effects of the microstructures (grain size, crystalline structure, compactness, et al.) and stoichiometry on the phase transition properties in the VO2 films in THz range, that is, the changes in the optical and electrical characteristics, the response and recovery speed across the phase transition. Especially, the phase transition properties in THz range for the VO2 film will be enhanced according to an improved microstructure and composition. Meanwhile, the metamaterial structures will be designed, simulated and then combined with the high quality VO2 films, for a corporate dynamic modulation function, in which the phase transition characteristics in VO2 film will be employed to affect the resonance of the metamaterial structure. Moreover, the electromagnetic transmission model will be analyzed to establish the dynamics operation mechanism of the combined structure. Our researches aim at developing a metamaterial based dynamic THz modulator combined with VO2 film, which possess a modulation depth over 80% and a modulation speed of 10 Mb/s.

针对太赫兹波段 Metamaterial动态调制器件调制深度和调制速率低的问题，利用VO2可逆相变过程中光电参数突变量大、相变快速的特点，以VO2薄膜为核心动态功能材料构建Metamaterial太赫兹动态调制器件。本项目在前期研究基础上，进一步系统研究VO2薄膜的微观结构（晶粒尺寸、结晶特性、致密度等）和掺杂组成对THz波段薄膜相变特性（光电参数变化幅度、相变响应和回复速率）的影响，制备高质量太赫兹VO2薄膜。同时，在Metamaterial结构模拟设计基础上，进行Metamaterial结构与高质量VO2薄膜的复合优化，通过VO2的相变去影响Metamaterial结构的电磁谐振，实现整体性的动态调制。并建立其复合电磁结构的电磁传输模型，分析其光电激励下的动态工作机制。研制出调制深度达到80%以上、调制速率达到10Mb/s的基于VO2薄膜的Metamaterial THz动态功能器件。

本项目针对太赫兹波段 Metamaterial动态调制器件调制深度和调制速率低的问题，利用VO2可逆相变过程中光电参数突变量大、相变快速的特点，以VO2薄膜为核心动态功能材料构建Metamaterial太赫兹动态调制器件。. 本项目系统研究了VO2薄膜的的生长模式，实现了不同微观结构（厚度、晶粒尺寸、结晶特性、致密度等）和掺杂组成（W、Ti掺杂）的VO2薄膜的可控制备，并研究了其对THz波段薄膜相变特性（光电参数变化幅度、相变响应）的影响。同时设计了基于ELC模型的开口环阵列的Metamaterial结构，实现了在THz波段的单谐振、多谐振功能。模拟并分析了VO2薄膜与金属Metamaterial阵列叠加和嵌入式复合结构的THz波透射幅度、频率动态调制效果和机理。通过微细加工制备了基于VO2薄膜的THz双谐振Metamaterial复合结构。采用340GHz连续波THz源对VO2/Metamaterial复合结构的调制速度和调制深度进行了测试，可以在340GHz频点实现幅度大于80%，速率达到1 MHz的调制功能。并针对VO2/Metamaterials复合结构对THz波的调制速度低于理论值的问题，采用THz泵浦-探测技术系统研究了VO2薄膜的超快相变特征，对薄膜的相变机制进行分析，并探讨了影响薄膜相变速度的微观机制。. 本项目的VO2/Metamaterials 动态调制器件的研究工作为二氧化钒薄膜在THz高效开关、调制等领域的应用提供了科学研究基础。