超快涡旋光在极性分子介质中的传输机理研究

With the deepening of the information age and the rapid development of various types of mobile communication services, the demand for improving communication capacity is also increasing. Due to the orbital angular momentum of the vortex laser, which offers a new degree of freedom in addition to light intensity, frequency and polarization, and, moreover, the number of which is theoretically infinite, its application can overcome the limitation of the traditional electromagnetic communication and greatly increase the communication capacity. Therefore, the propagation mechanism of the vortex laser has become hot issue in optical communication research aiming at larger capacity. In this project, taking polar molecules as the propagation media, the propagation properties of the orbital angular momentum of the ultrafast vortex laser, reshaping and its accompanying secondary radiation field, and the distribution of the high order vortex harmonic spectrum will be studied, and then the underling nonlinear physical mechanism will be probed into. In addition, the electron’s ultrafast dynamic processes and the scaling laws of its dependence on related parameters will also be investigated. Last but not the least, new methods to effectively control the ultrafast dynamic processes at the ultrashort time scale will be proposed.

随着社会信息化程度的不断加深和各类移动通信业务的迅猛发展，对于提高通信容量的需求也与日俱增。除光强、频率、偏振外，涡旋光具有一个额外的轨道角动量自由度，且可能的轨道角动量数理论上是无穷的，将其用于光通信可以突破传统的电磁通信容量的限制从而大幅提高通信容量。因此涡旋光传输机理的研究成为了当前大容量光通信领域中的前沿课题。本项目以极性分子为传输介质，研究超快涡旋光轨道角动量传输特性、光整形及其伴生的次级辐射新光场和高阶涡旋谐波谱分布，并系统地揭示其中的非线性物理机制。在此基础上进一步研究介质系统中的电子超快动力学过程及其对外界参数的依赖标定定律，从而提出在超短时间尺度内实现有效操控的新方案。

涡旋光具有无限的轨道角动量数，可用于提高通信容量，因此涡旋光传输机理的研究成为了当前大容量光通信领域中的前沿课题。借助少周期涡旋超短激光脉冲与非线性介质相互作用的麦克斯韦-布洛赫三维传输方程组和严格数值模拟程序，研究激光脉冲波形（如波长变化，空间分布不均匀性，啁啾补偿等）和非线性介质的特性改变对极端非线性光学新现象的影响，同时探讨了极端非线性光谱的强度和分布特点变化以及介质中的超快电子动力学新规律。重要结果如下：.1）研究了周期量级涡旋激光在介质系统中的传输效应，用横向电场分布直接解释了三次谐波掩盖下的二次谐波产生，比先前公开发表文章中的方法更方便和易操作[Physical Review A 96 (2017) 033854]。.2）研究了周期量级涡旋激光在极性分子系统中的传输响应，发现了奇偶次谐波并诠释了其产生的根源。相关工作发表可用于生物探测、通信和量子操控等领域[Optics Express 25 (2017) 21241]。.3）当空间非均匀涡旋激光与量子阱相互作用时，得到了“偶次谐波”。通过拓扑荷标定定律，发现这不是真正的偶次谐波，它仅仅是奇次谐波在偶次谐波位置处的拖尾增强效应。这种现象来自于激光脉冲短脉宽少周期效应超过了电场空间非均匀度效应[Optics Express 27 (2019) 37034]。