快响应可调谐超窄带原子光学滤波器研究

In recent years, the laser spatial information technology such as laser communications, remote sensing and lidar has a rapid development. However, the laser transmission in free space will suffer from broadband background radiation and the effect of dispersion medium, which leads to signal to noise ratio (SNR) of the optical system is very poor, so that the system cannot work well, and one of important ways to improve the SNR and the sensitivity of the system is the use of ultra-narrow bandwidth optical filter before the receiver. This project researches a rapid response tunable ultra-narrow bandwidth atomic filter based on laser induced anisotropy in the atomic vapor. The project begins with an analysis of the dynamics process of the circular polarization selective pumping in the two-level atoms, which have important significance to elucidate the selective optical pumping mechanism, and laid the theoretical foundation for this kind of filter; secondly, a method by using the Dynamic Stark Effect due to the strong pump field to obtain tunable transmission peak was proposed, and the tunability can be further expand by the introduction of magnetic field; finally, experiments will be arranged to obtain a wide range tunable spectrum and show that this type of filter has a faster response compared to other types of atomic filter. The research results of this project can not only provide a new way for atomic optical filter, but also be applied to quantum optics and nonlinear optics.

近年来，激光通讯、遥感和雷达等激光空间信息技术得到了高速发展。但是由于激光在自由空间中传输时会遭受宽带背景辐射以及色散介质的影响，使得这些光学系统的信噪比往往比较差，进而使系统不能很好地工作，而提高系统的信噪比和灵敏度的重要途径之一就是在系统接收端前使用超窄带光学滤波器。本项目基于原子蒸气中激光感生光学各向异性开展了快响应大范围可调谐超窄带的原子光学滤波器研究。项目首先分析了采用圆偏振光选择性泵浦二能级原子的动力学过程，对阐明选择性光学泵浦机制有着重要的意义，为此种滤波器奠定理论基础；其次提出了采用强泵浦场引起的动态斯塔克效应来获得可调谐的透射峰，并引入磁场辅助，使得调谐能力进一步扩大；最后，分别安排实验来获得大范围可调谐的透射谱并证明此种类型的滤波器相比于其他类型的原子滤波器有着更快的响应速度。本项目的研究成果不仅能为原子光学滤波器提供新的思路，还能应用到量子光学及非线性光学实验中。

近年来，激光通讯、遥感和雷达等激光空间信息技术得到了高速发展。但是由于激光在自由空间中传输时会遭受宽带背景辐射以及色散介质的影响，使得这些光学系统的信噪比往往比较差，进而使系统不能很好地工作，而提高系统的信噪比和灵敏度的重要途径之一就是在系统接收端前使用超窄带光学滤波器。本项目基于原子蒸气中激光感生光学各向异性开展了快响应大范围可调谐超窄带的原子光学滤波器研究。项目首先分析了采用圆偏振光选择性泵浦二能级原子的动力学过程，对阐明选择性光学泵浦机制有着重要的意义，为此种滤波器奠定理论基础，项目研究了泵浦光强度和外加磁场等因素对泵浦过程的影响，理论计算结果表明采用双光束泵浦的方式能将激发态的粒子数百分比提高到50%，而单光束泵浦只有31%;其次提出了采用强泵浦场引起的动态斯塔克效应来获得可调谐的透射峰，并引入磁场辅助，使得调谐能力进一步扩大的同时不会带来探测光透过率的降低，使得其波长调谐范围达到数个千兆赫兹，远大于没有磁场辅助的原子光学滤波器；最后，分别安排实验来获得大范围可调谐的透射谱并证明此种类型的滤波器相比于其他类型的原子滤波器有着更快的响应速度。本项目的研究成果不仅能为原子光学滤波器提供新的思路，还能应用到量子光学及非线性光学实验中。