掺铥光纤泵浦-漂白效应及其主动抗辐照技术

It's well-known that high-energy particle radiation can cause the decreased and even failed performance of fiber and other waveguide device. Since the thulium-doped silica fiber laser with the output wavelength of 2 micron becomes more and more widely used in the environment with radiation, the demand of detailed research of radiation effect and development of radiation resistance technology of Tm-doped fiber laser becomes urgent. The application of Tm-doped fiber laser includes space exploration, space communication, optoelectronic countermeasures and so forth. Unlike fibers with other rare-earth elements doped, Tm-doped fiber has its unique pump bleaching feathers because the wavelength of pump laser of Tm-doped is 793nm which exactly located at the absorption sideband caused by radiation. Aimed at this unique property, this project will focus on researching some significant questions, including the physical mechanisms of pump-bleaching effect, the radiation effect recover of irradiated fiber effected by multiple factors, the kinetics of pump-bleaching effect, manufacturing the applicative pump-bleaching Tm-doped fiber and developing the active anti-irradiation technology of Tm-doped fiber laser. Implementation of this project will contribute to the development of new anti-irradiation fiber material, discovery of the microscopic mechanism of radiation -pumping bleaching effect of thulium-doped fiber, establishment of new pump-bleaching theoretical model and promotion of the applications of thulium-doped fiber materials and devices in space and other harsh environments.

高能粒子辐照可导致光纤及其器件性能下降，甚至失效。具有2微米输出的掺铥光纤及其激光器，未来将在辐照环境中应用越来越广泛，包括太空探测、空间通信、光电对抗等，因此研究其辐照、抗辐照性能相当迫切。与其它掺杂光纤不同，掺铥光纤由于其泵浦波长793nm处于辐致色心吸收边带，有自己独有的泵浦-漂白特性。针对这个特性，本项目拟在前期研究基础上，重点研究泵浦-漂白效应的物理机制，多因素影响下的光纤辐照恢复特性，以及泵浦-漂白效应的动力学过程，制备适合泵浦-漂白的掺铥光纤，探索掺铥光纤激光器的主动抗辐照技术。开展以上研究将有助于发展具有自泵浦-漂白效应的抗辐照光纤新材料，发现掺铥光纤辐照-泵浦漂白效应的物理机制，建立相关理论模型，推动掺铥光纤材料及其器件在太空等辐照环境中的应用。

基于MCVD制棒工艺和液相掺杂技术，介绍了高性能双包层掺铥石英光纤的制备过程。通过优化掺杂浓度、比例和剖面设计，实现了2微米光纤激光400W输出，是目前国产掺铥石英光纤最高输出功率。基于稀土掺杂光纤在辐照环境应用需要，探究了掺铥石英光纤在辐照环境中的光学特性，并发现了掺铥光纤具有泵浦漂白特性。掺铥石英光纤在受到伽马射线辐照后，其激光斜率下降；在可见光及近红外波段出现明显的附加吸收损耗。且辐照剂量越大，上述现象越明显。在793nm半导体泵浦源稳定持续泵浦下，掺铥光纤的输出功率会渐渐提升，斜率效率明显回升，在可见光及红外波段的附加吸收损耗也逐渐消失，即掺铥光纤在自身泵浦源的作用下，其光纤性能得到了恢复，说明掺铥光纤具有泵浦漂白特性。但泵浦漂白的缺陷是依然不能够让受到大剂量辐照的掺铥光纤得到彻底的恢复。除了光漂白以外，掺Ce、载氢、掺F等措施也能够让有源光纤的抗辐照能力提升。将泵浦漂白和上述措施有机结合，可能会进一步提高掺铥光纤的抗辐照能力。提出对掺铥光纤进行氘化处理的方案，该方案可明显提升掺铥光纤的抗辐照特性，并且探究了多剂量辐照下对掺铥光纤进行载氘处理的漂白效果，为掺铥石英光纤在辐照环境中的应用和光子暗化机理及漂白方法的探究提供了理论和实验基础。