全光型分子速度滤波的理论研究及数值模拟

Cold molecules offer some new opportunities for molecular spectroscopy and precision measurements, molecular collisions and cold chemistry, and so on. Generation and controlling of cold molecules is one of the frontlines of molecular optics. In this project, we will carry out a systematic theoretical investigation on all-optical molecule velocity filter and cold molecular beam generation. Cold molecules will be trapped, guided and controlled by the dipole forces coming from some given optical fields. And cold molecules will be filtered from the input thermal samples and compose cold molecular beams by using some bend optical molecule guides. Since optical fields can interact with all kinds of molecules, our all-optical schemes are rather versatile than electrostatic or magnetostatic ones. To achieve the project objectives, we will combine theoretical analysis with numerical simulation, classical modles with quantum ones and analytical solution with numerical calculation to fumble feasible experimental schemes, and then give theory evidence and technical basis. Cold molecular technique and molecular optics can be developed by this project accordingly.

冷分子在分子光谱、精密测量、分子冷碰撞及冷化学等方面有着非常重要的应用，冷分子的产生及操控是分子光学的前沿。本项目围绕中性分子的全光型速度滤波及冷分子束的产生开展理论方案的研究和探索。计划借助于光场与分子的相互作用实现分子的囚禁、导引及操控，采用弯曲导引及速度滤波实现连续或准连续冷分子束的产生，特别是利用光场可与所有分子发生相互作用这一优点解决非极性非磁性分子至今仍不可被导引及速度滤波的难题。通过分析了解分子全光型导引亟待解决的研究壁垒及技术瓶颈，尝试设计有效导引及速度滤波分子束的新方案。通过理论研究和模拟相结合、经典和量子相结合以及解析和数值相结合的方法摸索出切实可行的实验方案，为中性分子的激光导引提供理论依据及技术参考，推动冷分子技术及分子光学的发展。

本项目围绕中性分子的全光型导引及冷分子束的产生开展理论方案的研究和探索，主要提出一个可控的全光型速度滤波方案，该方案采用两束交会的腔增强红失谐光束制成，用以产生一束或两束非极性非磁性冷分子。本项目对碘分子速度滤波的动力学机制和分束过程进行了三维蒙特卡洛模拟，研究表明：调整两束激光的功率差使其从-124W变化到124W时，两臂出射分子数的分束比从10.3%变化到89.7%；同时调整两驻波腔的交会角使其从80度变化到10度，出射分子束的分束比从1.6%变化到98.4%。当倾斜导引的分子束和直导引的分子束之间的交会角为80度时，该速度滤波器可产生纵向温度为8mK，纵向速度分布的半高宽度为1 m/s的冷分子束。