中红外激光在环境监测、医疗、光电对抗等领域有重要应用价值，特别是2.1μm激光，因波长避开非线性晶体ZnGeP2和LiInSe2等的截止吸收边，是3~12μm OPO的重要泵浦源。本课题拟发展一种新型便捷的2.1μm激光实现方式，直接采用785nm LD泵浦，通过Tm:YAG与Ho:YAG晶体键合并采用共腔、同带泵浦机制来获取高效Ho激光输出。我们新提出的Tm/Ho键合激光器在窄线宽LD泵浦和Tm离子间交叉弛豫下，能够高效地产生禁锢于腔内的2.02μm激光并与Ho:YAG的次吸收带相匹配，具有小于5%的量子亏损，从而可实现高效的室温Ho激光输出。项目组在前期已对该机制进行了初步的实验论证，基于此，我们将研究同腔共振下Tm激光与Ho激光此消彼长、由强变弱到消失的物理现象和机理，以及高功率运行下的热效应管理等问题，探索出一条可实现高功率、小型化、常温制冷、常规LD泵浦2.1μm激光的有效路径。

Mid-infrared lasers are important in fields such as environmental monitoring, medical treatment, and photo-electronic countermeasure. Especially, wavelength aound 2.1μm from Ho laser is away enough from cutoff sides of the famous Mid-infrared non-linear crystals such as ZnGeP2 and LiInSe2 with low absorption losses, which is an important OPO pump source for generating high power 3~12 μm Mid-infrared lasers. For the urgent requirement of a high-efficient and miniaturized Ho laser, in this submitted application we propose a novel Ho laser mechanism, which is an co-cavity in-band pumped Ho laser with the Ho:YAG gain medium diffusion-bonded with a Tm:YAG gain medium. In this mechanism, efficient Tm laser could be generated from the 785 nm LD and confined intra-cavity, where the 2.02 μm wavelength is within the absorption side-band of Ho:YAG crystal with small quantum defect (＜5%). Hence, efficient high-power Ho laser could be generated from a single bulk composite gain medium directly pumped by a normal 785 nm LD at room-temperature. Compared with other existed Ho laser mechanisms, the Tm/Ho composite laser is more accessible, compact, and efficient. Before this submission，we have verified the robustness of this novel mechanism in preliminary experiment. Furthermore, we prepare to carry out researches about the Tm/Ho composite laser in illustrating the dual-wavelength phenomenon at low lasing power where the Tm laser goes from strong to weak and to vanished, and in thermal effects and laser stability when scaling up the Ho laser power, and so on. With the above researches, we try to explore an effective route for a compact room-temperature normal LD pumped Ho laser with high-power and high-efficiency.