Er3+掺杂氟氧化物微晶玻璃光纤的制备及2.7 μm发光机理研究

2.7 μm band is located in the transparent widow of atmosphere, thus, the fiber laser operating at this band is widely applied in the military and civil fields. Recently, Er3+-doped ZBLAN fiber is widely used for the optical gain medium of the 2.7 μm fiber laser. However, it’s lower optical gain and poorer chemical and mechanical properties seriously hinder the further development of 2.7 μm fiber laser. This project replace ZBLAN glass by oxyfluoride silicate glass-ceramics as host material to improve the physicochemical properties of the fiber, and control the surrounding field environment of Er3+ by precipitating CaF2 nanocrystals. Due to the lower maximum phonon energy of CaF2 nanocrystals, the luminescence efficiency of Er3+ can be improved. Firstly, studying the influence of the size, morphology and distribution of CaF2 nanocrystals on the 2.7 μm luminescence of Er3+ to reveal its luminescence mechanism, then design the precursor glass composition and fabricate the oxyfluoride silicate glass-ceramic. Then, studying the influence of fiber drawing technology on the size, morphology and distribution of CaF2 nanocrystals in the fibers to construct a second growth mode of CaF2 nanocrystals during the fiber drawing. Finally, optimizing the fiber drawing parameters and fabricating the glass-ceramic fibers with higher optical gain and lower loss at 2.7 μm band which has potential application prospect in the higher power and efficiency fiber laser.

2.7 μm光纤激光器的工作波长位于大气“透明窗口”，在军民两用具有广阔的应用前景。而目前采用的锆系氟化物掺Er3+光纤在2.7 μm处增益较低且其物化性能较差，严重阻碍了该波段光纤激光器的研究进展。本项目采用硅酸盐氟氧化物玻璃作为光纤基质来提高光纤的物化性能，通过析出CaF2纳米晶来调控Er3+周围场环境，利用CaF2纳米晶低声子能量特性来提高Er3+ 在2.7 μm处发光效率。首先，研究CaF2纳米晶尺寸、形貌及分布对Er3+ 2.7 μm发光性能影响规律，揭示其发光机理，设计优化玻璃组成并制备Er3+掺杂硅酸盐氟氧化物微晶玻璃；其次，研究拉丝工艺对CaF2纳米晶尺寸、形貌及分布的影响规律，构建其二次生长模型，优化微晶玻璃光纤拉丝工艺，通过在高温制备微晶玻璃纤芯，在低温拉丝制备在2.7 μm处具有高增益、低损耗的Er3+掺杂微晶玻璃光纤，为该波段光纤激光器的发展奠定科学依据与物质基础。

本研究采用氧化物玻璃作为光纤基质来提高光纤的物化性能，通过在纤芯中析出纳米晶来调控铒离子周围场环境，从而提高其在2-4μm波段发光效率。本项目的研究内容主要包括铒离子在微晶玻璃中中红外发光机理及铒离子掺杂微晶玻璃光纤的制备。通过本项目的实施，得到的主要结果如下：.1）通过设计优化微晶玻璃前驱体玻璃组分、优化热处理工艺参数制备出了铒掺杂透明氟硅酸盐、氟锗酸盐、氟磷酸盐微晶玻璃，通过控制玻璃中析出晶体的尺寸均实现了铒离子2.7μm发光增强；.2）通过设计优化微晶玻璃光纤纤芯组分及热处理工艺参数，制备出商用H-FK69B玻璃作为包层，铒离子掺杂氟磷酸盐微晶玻璃作为纤芯的微晶玻璃光纤；.3）通过系统研究铒离子在玻璃中各个能级的非辐射跃迁概率影响因素，明确了铒离子2.7μm和3.5μm的发光机理，在此基础上提出通过增加铒离子之间交叉驰豫的方式来提高铒离子在3.5μm波段的发光性能，并在碲酸盐玻璃中得到验证。.通过本项目的实施，明确了铒离子在中红外波段的发光机理，并在此基础上提出了有效的增强其中红外发光的途径，为进一步设计铒离子掺杂中红外增益介质材料提供了一定的理论依据；同时本项目中光纤的制备方法为制备其他稀土掺杂微晶玻璃光纤的制备提供了一定的参考意义。