基于双光子共振激发机制的二极管泵浦碱金属蒸汽蓝光激光器研究

Blue lasers have many potential applications such as underwater optical communication, Marine resource exploration, high-density optical storage, biomedical field, etc.. The sdudy of scalable blue lasers with good beam quality, high efficiency has important scientific significance and application value. This project proposed a new mechanism for blue laser: two-photon resonant excitation diode pumped alkali vapor blue lasers. Two narrow linewidth diode lasers are used as pump source. The alkali atoms are exicited from the ground state nS to the excited state nD based on two-photon resonant excitation mechanism, by the resonant collision with buffer gas, alkali atoms quickly relaxed to the upper laser level (n+1)P and form population inversion with the ground state nS, and then blue laser is generated. In this project, we planed to carry out following theoretical and experimental studies: (1) Using dye lasers as alternative light sources, study the mechanism of two-photon pumped alkali vapor blue laser; select the best buffer gas; Optimize the operation conditions of blue lasr. (2) Implement and optimize the diode pumped alkali vapor blue lasers, Including the development of high-pressure gain cell, the design and optimization line width narrowing system and the beam shaping system of the diode pump source. (3) Design and demonstrate the amplification scheme of the new laser system. We expect that through the study of this project, a new kind of good beam quality, high efficiency scalable blue laser will be demonstrated.

蓝光激光器在水下光通信、海洋资源探测、高密度光存储、激光生物医学等领域具有广泛的应用前景。研制光束质量好、效率高、可放大性强的蓝光激光器具有重要的科学意义和应用价值。本项目提出了一种获得蓝光的新机制：其采用窄线宽二极管激光器作为泵浦源，利用双光子共振激发机制，将碱金属原子由基态nS激发到激发态nD，通过缓冲气体的共振碰撞，快速弛豫到激光上能级（n+1）P，并与基态nS产生粒子数反转，进而产生蓝光。本项目重点开展以下理论和实验方面的研究工作：（1）染料激光器替代光源双光子泵浦碱金属蒸汽产生蓝光的机制研究，筛选最佳的迟豫气体，优化蓝光的出光条件；（2）二极管泵浦碱金属蒸汽蓝光激光器的实现与系统优化，包括高压增益池的研制，二极管泵浦源的线宽压窄及光束整形设计及优化；（3）新激光体系放大方案的设计及论证。我们希望通过本项目的研究，实现一种光束质量好，效率高，可放大性强的蓝光激光器。

采用778nm单色双光子泵浦碱金属铷蒸汽，获得了420nm蓝光激光，峰值功率达到1000W，转化效率大于1.5%。对420nm蓝光能量随温度、泵浦光能量、波长的变化和420nm蓝光光束质量进行了深入研究。对碱金属蒸汽激光器核心技术碱金属增益池的充装进行了研究，搭建了碱金属增益池充装平台手套箱系统，对碱金属增益池的充装工艺进行了研究，采用自主研制的碱金属增益池获得了795nm碱金属激光输出。通过本课题的研究，掌握了碱金属蒸汽激光器核心技术碱金属增益池的研制，为未来碱金属蒸汽激光器的研制打下了坚实的基础。碱金属激光器420nm蓝光的获得，丰富了碱金属蒸汽激光器的输出波长，在水下光通信、海洋资源探测、高密度光存储、激光生物医学等领域具有广泛的应用前景。