超快激光成丝现象中的THz波空间强束缚效应研究

The proposal will study the strong spatial confinement of THz pulse during femtosecond laser filamentation. Due to this strong confinement, the diameter of the THz pulse inside the filament is only a few tens micrometer, which is much small than the THz pulse wavelength. It has promising application in sub-wavelength resolution THz image. Since filament generated THz pulse also features high strength, broad bandwidth, this strong spatial confinement of THz pulse during the filamentation is very interested in wide range of research fields, such as bio-medical, physics and chemistry and so on. The proposal will study the two dimensional near field THz imaging technique, the physical mechanism of the confinement and the theoretical model to describe the spatial-temporal transformation of the THz pulse inside the filament. The goal of the proposal is to obtain the information about the near field characteristics of the THz pulse under various experimental conditions, to understand its underlying mechanism and to establish the corresponding theoretical model to guide the coherent control of the THz pulse inside the filament. Finally, it is possible to evaluate the ultimate performance of the proposed sub-wavelength THz imaging by using the strongly confined THz pulse inside the filament. The applicant has contributed to the first study of the strong spatial confinement of THz pulse during femtosecond laser filamentation in the world. Continuing the study under the support of NSFC will help us to make further understanding about this interesting phenomenon and pave the way to the application in bio-medical, physics and chemistry. It will also certainly help us to maintain the leading position in this direction and make high quality research in the field.

项目研究超快激光成丝中的太赫兹（THz）波空间强束缚效应。在该效应作用下，光丝中的THz波直径是波长的数十分之一，可应用于具有亚波长分辨率的THz波波谱成像，充分利用光丝产生THz波强度高、带宽宽的优势，在生命医学、物理、化学等领域具有重大应用前景。项目将围绕亚波长尺度THz波空间强度分布的二维测量技术、光丝等离子体与THz波相互作用动力学过程、成丝过程中THz波时空演变物理模型等关键科学问题开展研究。研究工作预期将掌握实验参数影响THz波强束缚效应的实验规律；理解该效应产生物理机制，建立相应物理模型；并提出优化光丝内THz波空间模式分布、频谱宽度及强度等性能参数的调控技术；进而明确该效应应用的极限性能。申请人课题组在国际上较早开展光丝中的THz波空间强束缚效应研究，本项目开展将能使我们获得领先的理论知识和实验技术，保持我们在相关研究领域的国际领先水平，有力促进成丝产生THz波应用。

项目研究超快激光成丝中的太赫兹（THz）波空间强束缚效应。在该效应作用下，光丝中的THz波直径是波长的数十分之一，可应用于具有亚波长分辨率的THz波波谱成像，充分利用光丝产生THz波强度高、带宽宽的优势，在生命医学、物理、化学等领域具有重大应用前景。项目主要研究内容包括：不同实验参数下光丝产生THz波的空间直径、频谱特征、偏振态等主要参数演化实验规律；成丝动力学过程及THz波强束缚效应的物理机制，建立相应的物理模型；THz波性能参数的调控技术等。通过项目研究，取得了以下主要成果：提出太赫兹负介电波导模型，解释飞秒激光成丝中太赫兹强束缚效应物理机制，为解决长久以来本领域对于THz产生机制的争论提供新思路；基于太赫兹负介电波导模型，完善光丝产生太赫兹脉冲物理模型；发现光丝中的太赫兹双折射现象，基于这一现象利用正交双电极静电场实现对于THz波椭偏度、手性方向及能量等参数的有效调控；基于空间走离补偿，实现太赫兹能量优化；研究结果成像分辨率可达到5um；实现飞秒激光传输多丝竞争动力学可视化研究技术；提出秒激光脉冲传输时间分辨非线性动力学演化特性研究新方法；设计并制备多种基于非对称结构超材料的宽带THz波调控器件；实现3D打印低损耗THz波导。基于项目研究成果，发表高水平研究论文32篇，其中SCI收录24篇；授权发明专利6项；国际学术会议邀请报告9次；负责人作为第一完成人获得天津市自然科学一等奖、天津市专利金奖、优秀奖等奖励；项目执行期培养已毕业博士、硕士研究生9名，培养学生获得天津市研究生党建工作优秀党员标兵、天津市优秀博士论文、天津市大学生创新奖学金特等奖、天津市知识产权创新创业发明与设计大赛一等奖、南开大学研究生优秀毕业生等荣誉。