涡旋飞秒激光驱动的分子高次谐波研究

The combination of orbital angular momentum of femtosecond vortex laser and high temporal and spatial resolution of high-order harmonic will provide us new tool for deep insight into the macroscopic world. However, the research involved this combination is confined to atoms to date. Comparing with atoms, molecules have more freedom, and consequently the radiated harmonic spectrum contains more information. In this project，we use both theoretical and experimental method. In theory, appropriate models are set up to analyze the couple of molecular and photonic angular momentum, and as well as the dynamics of molecular quantum path. In experiment, the angular momentum and the spectrally resolved temporal and spatial features of the harmonic radiation are researched, in order to reveal the mechanics of the generation of molecular harmonic driven by femtosecond vortex laser. We believe this will pave the way to the basic science problems such as the detection of molecular structure and the evolved transition of electronic state.

涡旋飞秒激光具有轨道角动量的特性与高次谐波的高时空分辨相结合将为人们深入研究微观世界提供新的工具，然而目前国际上将二者结合起来的研究还只局限于原子。与原子相比分子具有更多的自由度，其与涡旋激光作用的机理也更复杂，从而辐射出的高次谐波谱中也包含了更多的信息。本项目拟采用理论与实验相结合的研究手段。建立合理的理论模型分析光子与分子的角动量耦合以及分子的量子通道动力学行为，给出更清晰的具有角动量的光子与分子的相互作用图像。实验上通过研究分子高次谐波辐射的角动量以及谱分辨的时间以及空间特性，揭示涡旋飞秒激光驱动下分子高次谐波的辐射机理，从而为开拓在探测分子结构以及电子态演化跃迁等基础科学问题方面的应用打下基础。

在本项目的执行过程中，我们完善了飞秒激光与分子体系乃至更复杂的固态体系相互作用下高次谐波产生及辐射的理论并建立了飞秒激光脉冲整形与分子高次谐波测量实验平台。提出了利用分子高次谐波辐射实现分子轨道波函数单发成像、椭圆偏振以及涡旋阿秒脉冲的产生与调控、手性分子异构体的诊断等的系列新方案。此外，我们还将研究拓展到涡旋光电子的产生与调控方面，通过反向双色圆偏激光与环流态分子相互作用，实现了对电子涡旋的拓扑荷数的调控。