基于超表面材料的矢量太赫兹脉冲紧聚焦及其在超分辨成像中应用研究

Terahertz wave has some unique and novel properties, including low photon energy, strong penetrability for the materials such as plastics, ceramics, fibre and so on, the fingerprint spectrum of biological macromolecule motion, carrier motion and other motion. For these properties, terahertz imaging has a great value in biology, food, material science and other fields. However, due to the limitation of diffraction limit, terahertz far-field imaging is difficult to distinguish objects smaller than its wavelength, we need to achieve super-diffraction resolution imaging. Although near-field imaging is not limited by the diffraction limit, it can only image the surface of the object but not the interior of the object. Therefore, the realization of terahertz far-field super-resolution imaging is of great significance for the internal imaging of objects. The tightly focusing of vector optical field can obtain the super-diffraction limit size spot, which is expected to achieve terahertz far-field super-resolution imaging. In this project, we will generate and tightly focus the vector terahertz pulse by use of metamaterials, and rearch the characteristics and its relevant new physical effects. Then, we build the terahertz time-domain spectral imaging system to realize the terahertz far-field super-diffraction imaging by use of the super-diffraction limit size spot after tightly focusing vector terahertz pulse. It will be applied in the fields of internal imaging of biological tissues, nondestructive testing of materials and other fields, and it will promote the development of related fields.

太赫兹波具有一些独特且新颖的特性，例如太赫兹波的光子能量低，对塑料、陶瓷等材料具有很强的穿透性，为生物大分子运动、载流子运动等运动的指纹谱。这些特性使得太赫兹成像在生物、食品、材料等领域具有巨大的应用价值。但受衍射极限限制，太赫兹成像难以分辨小于其波长的物体，因此需要实现超衍射分辨成像。虽然近场成像不受衍射极限限制，但其只能对物体表面而不能对物体内部进行成像。因而实现太赫兹远场超分辨成像对于物体内部成像具有重要的意义。而矢量光场的紧聚焦可获得超衍射极限尺寸的光斑，有望在太赫兹波段实现远场超分辨成像。本项目利用超表面材料实现矢量太赫兹脉冲高效生成和紧聚焦，并研究其紧聚焦特性及相关的新物理效应。然后，搭建太赫兹时域光谱成像系统，利用紧聚焦矢量太赫兹脉冲后获得的超衍射极限尺寸光斑实现太赫兹远场超衍射成像。这将应用在生物组织内部成像、材料无损检测等领域，并推动相关领域发展。

太赫兹光谱和成像已广泛用于生物、食品、半导体材料等领域，研究太赫兹脉冲紧聚焦特性有利于提高太赫兹光谱检测或成像系统的性能，并将在食品检测、半导体材料特性检测、生物大分子检测等领域具有重要的应用价值，太赫兹矢量光场特性及其生成在太赫兹通信、太赫兹检测和成像等领域将产生重要的应用价值。理论分析了太赫兹脉冲矢量光场的紧聚焦场特性，通过模拟获得了太赫兹脉冲矢量光场的紧聚焦场的空域分布、时域分布和频谱分布，对于太赫兹时域光谱用于检测或成像具有重要的参考价值。基于有效折射率或有效阻抗理论，获得了线栅调控光场的公式，通过调控线栅周期、线栅占空比、线栅方向等空间分布来调控光场，获得矢量涡旋光场，对于利用金属超表面生成矢量光场领域具有一定的理论指导作用。提出通过matlab编程制图辅助激光直写方法实现任意复杂结构的制备方法；提出了基于聚类分析图像处理方法控制多焦斑阵列并行加工复杂结构方法；通过Labview控制三维电动平移台、机械开关等仪器并利用飞秒激光直接切割金属微米薄片制备微纳结构方法，并利用LABVIEW软件编程控制三维电动平台等元器件实现样品的扫描成像。实现了太赫兹时域光谱系统和探测系统的搭建，用于实验室材料特性以及太赫兹探测器的表征，基于超材料并利用太赫兹时域光谱系统检测生物大分子状态和浓度，为重大疾病诊断、生物分子研究等提供一种手段。