Cr2+:II-VI晶体/硫系玻璃复合光纤，兼具Cr2+:II-V高功率、宽带可调谐的中红外激光特性及光纤易于热管理的优势，是当前激光工作者关注的研究热点之一。然而针对该类型光纤的现有研究存在光纤损耗高尚无激光输出，且抽运方式复杂的问题。对此，本项目提出通过新系统玻璃开发和热处理工艺优化在硫系玻璃光纤中原位析出Cr2+:II-VI纳晶的新方法制备复合光纤，同时在光纤中掺入稀土离子并借助其敏化作用，实现在简化抽运方式，即商业化成熟的半导体激光器直接抽运下产生Cr2+中红外2-3µm激光发射。项目将深入研究“组成-结构-热处理”影响玻璃析晶的规律及机理，实现复合光纤的可控制备；还将研究稀土离子和Cr2+:II-VI纳晶的微观分布及敏化发光的物理机制。研究成果将为开发大功率、宽带可调谐连续及超短脉冲中红外光纤激光器提供关键的基础材料，并有望在化学、生物、医学及军事国防等多个领域发挥重要应用。

Cr2+:II-VI crystal/chalcogenide (ChG) glass composite fibers, combining the advantages of high output power, wide wavelength tuning range of the Cr2+:II-VI crystal and ease of thermal management of the ChG fiber, have attracted worldwide interest. However, current studies suffer from the following drawbacks such as absence of lasing due to high optical loss of the fibers and extremely complex pumping. In this context, this project aims to make a new type of composite fibers based on Cr2+:II-VI nanocrystal/chalcogenide glass composites. A series of new ChG glass systems will be developed, based on which Cr2+:II-VI nanocrystals embedded ChG glasses will be prepared by controlled thermal treatment. Rare-earth elements will be doped in the composite fibers acting as the sensitizers for the Cr2+:II-VI nanocrystals. Therefore, the pumping can be realized in a far simpler way, viz., directly using the commercially available laser diodes as the pump sources for the Cr2+ lasing in the mid-infrared range of 2~3 µm. We will study comprehensively the influence of the composition, structure and thermal treatment on the crystallization behaviors of the fiber and the underlying mechanisms. The target is to realize controllable synthesis of the composite fibers. On the other hand, we will also study the distributions of rare-earth ions and Cr2+:II-VI nanocrystals in the composite fibers as well as the photoluminescence sensitization mechanisms. The composite fibers developed in this project will be promising gain media for high power, wide tunability continuous and ultra-short pulsed mid-infrared fiber lasers. The materials will also find a wide range of applications in chemistry, biology, medicine and national defense etc..