Ramírez-Martínez N J, Núñez-Velázquez M, Umnikov A A, Sahu J K
Opt Express. 2019 Jan 7;27(1):196-201. doi: 10.1364/OE.27.000196.
We report a hybrid process by combining both vapor-phase and solution-doping techniques of rare-earth doped preform fabrication in conjunction with the MCVD technique, in order to fabricate highly efficient Tm-doped laser fibers. The proposed fabrication route takes advantage of co-doping silica with high alumina content through the vapor-phase doping process, which is otherwise difficult to achieve using conventional solution doping technique. In addition, by employing the solution doping method, high-purity thulium halide precursors that have low vapor pressures up to several hundred degree Celsius. These high-purity thulium halide precursors can be used to dope the fiber core region with a high thulium concentration that is optimized for an efficient two-for-one cross-relaxation process for 79xnm diode pumped thulium-doped fiber laser. Fibers fabricated using the hybrid approach show more homogeneous and flat-top dopant profiles, compared with the conventional approach, where both aluminum and thulium are incorporated in the core through solution doping. This will ensure that more doped region will take part in the cross-relaxation process. Superior laser performance with a slope efficiency of >70% in the two-micron band has been demonstrated when diode pumped at ~790nm.
我们报告了一种混合工艺，该工艺结合了气相和溶液掺杂技术来制造稀土掺杂预制棒，并与MCVD技术相结合，以制造高效掺铥激光光纤。所提出的制造路线利用气相掺杂工艺对高氧化铝含量的二氧化硅进行共掺杂，而这用传统的溶液掺杂技术很难实现。此外，通过采用溶液掺杂方法，可以使用在高达几百摄氏度时具有低蒸气压的高纯度卤化铥前驱体。这些高纯度卤化铥前驱体可用于以高铥浓度掺杂光纤芯区，该浓度针对790nm二极管泵浦掺铥光纤激光器的高效二对一交叉弛豫过程进行了优化。与传统方法相比，采用混合方法制造的光纤显示出更均匀和平顶的掺杂分布，在传统方法中，铝和铥都是通过溶液掺杂掺入芯区的。这将确保更多的掺杂区域参与交叉弛豫过程。当在~790nm处进行二极管泵浦时，已证明在两微米波段具有>70%的斜率效率的优异激光性能。
