全固态光泵浦Dy:YAG陶瓷黄光激光特性研究

Yellow lasers have many important applications in biomedical field, such as fluorescence imaging, flow cytometry, laser photocoagulation and so on. Due to the low power stability and the bigger size, the existing lasers are difficult to meet the requirements in practical application. In this project, a one-step method is proposed. By optical pumping the Dy:YAG ceramics, a miniature, 579/583 nm laser with high-stability and high-brightness is demonstrated. The Dy:YAG ceramics enables good fluorescence lifetime and low loss even if the doped concentration of Dy3+ is high. Thus, by employing the highly doped Dy:YAG ceramics, together with increasing the optical length of absorption, a satisfactory pump efficiency is achieved. Based on numerically simulation, a cavity insensitive to the thermal-lens is designed and a good mode-match between the pump mode and the oscillating mode is accomplished. This ensures the laser operation with high-brightness and high-stability in theory. Finally, on the basis of the study on the mechanism of yellow laser generation and the numerical simulation, an all-solid-state Dy:YAG ceramics laser at 579/583 nm is demonstrated for the first time. This proposal presents a new thinking in the medical yellow laser with small size and high power stability.

黄光激光器在荧光显微成像、流式细胞术、眼科光凝等生物医学领域有着重要的应用前景。目前的黄光激光器存在输出功率稳定性差、体积较大等缺点，难以满足实际应用的要求。本课题提出采用光泵浦Dy:YAG陶瓷的一步式方案，实现高稳定性、小体积、高光束质量的579/583 nm黄光激光输出。本课题拟采用Dy:YAG陶瓷作为激光介质，解决传统单晶无法兼顾高掺杂浓度和高荧光寿命、低损耗的问题；并通过进一步增加吸收光程，实现激光介质对泵浦光的充分吸收。通过数值模拟设计对热效应不灵敏的谐振腔，并优化泵浦光和振荡光之间的模式匹配，从理论上保证激光器的高光束质量、高效率运转。在能级跃迁理论分析和数值模拟计算的基础上，优化设计方案，首次在Dy:YAG陶瓷中实现全固态579/583 nm黄光激光输出。本课题提出了一种实现稳定性好、体积小的医用黄光激光器的新思路。

黄光激光器在荧光显微成像、流式细胞术、眼科光凝等生物医学领域有着重要的应用前景。目前的黄光激光器存在输出功率稳定性差、体积较大等缺点，难以满足实际应用的要求。本课题提出采用光泵浦Dy:YAG介质的一步式方案，实现高稳定性、小体积、高光束质量的583 nm黄光激光输出。项目主要取得的进展为：1）完成了Dy:BSO单晶、Dy:YAG、Dy,Tb: YAG单晶和国产、日本Dy:YAG陶瓷激光介质的吸收谱、发射谱和散射损耗测量，对于掺Dy激光介质的参数对比提供了原始数据。2）首次采用国产晶体（中科院安徽光机所生长），获得了Dy介质的黄光激光输出，最大单脉冲能量超过1 mJ。这也是美国海军实验室之后，第二个能够获得583 nm黄光激光输出的报道。相关结果分别通过简讯和长文形式发表在《中国激光》上，其中长文被评为中国激光杂志社2017第4期优秀论文。3） 通过Dy:YAG的荧光谱，发现Dy:YAG在580-590 nm谱区存在多条谱线，为可调谐黄光激光实验研究提供了思路。