基于能级调控技术实现掺Er3+倍半氧化物透明陶瓷3μm高功率激光输出的研究

High power laser sources, operating at around 3μm, are of great importance for the applications in national defense security, medicine, communication, remote atmospheric sensing, and pollution monitoring. However, the high power 3μm CW emission of erbium-doped lasers has so far been severely hindered by the unfavorable energy level lifetimes and the large quantum defect of the lasers. The bottleneck of the practical development of LD pumped 3μm CW emission of erbium-doped lasers is in the material. This project focuses on Er3+ ions doped sesquioxide ceramics which have potential applications in 3μm laser output. Synthesis of high quality transparent ceramics, control of Er3+ energy level and improvement of thermal effect in laser system are investigated. Based on energy level control technology, in the project, we propose two new solutions to achieve high power 3μm laser output in low Er3+ doped. Specifically, the 3μm ceramic lasers under simultaneous resonant pumping of a 976nm and a 1.6μm laser, or under resonant pumping of a 976nm laser but simultaneously oscillates at the 3μm and the 1.6μm will be theoretically simulated based on the laser rate equation theory, and experimentally investigated. The self-terminating transition and the serious thermal problem in the lasers will be solved and valuable 3μm mid-infrared laser materials and lasers with independent intellectual property rights will be developed.

2.7-3μm高功率激光光源在国家安全、生物医学、通讯、远程大气遥感及环境监测等方面具有重要需求，但由于该波段激光器的功率水平普遍较低，其技术水平远落后于可见光或1μm波段激光器。LD泵浦的2.7-3μm波段激光器的实用化发展瓶颈关键在材料。本项目针对目前具有应用潜力和研究基础的掺Er3+倍半氧化物透明激光陶瓷材料（Er:Y2O3、Er:Lu2O3）作为激光介质，利用激光陶瓷在离子掺杂和结构设计上的灵活性及优势，采用能级调控技术强制抽空3μm跃迁激光下能级粒子数，基于掺铒倍半氧化物透明陶瓷设计976nm和1.6μm双波长泵浦以及1.6/3μm双波长振荡的高功率连续激光器，开展关于高质量透明陶瓷制备、Er3+离子能级调控、激光器热效应改善设计等方面的基础研究，以期能有效抑制掺铒3μm波段激光振荡自终止现象和改善其高功率运转热效应等问题，发展具有实用价值和自主知识产权的3μm波段中红外激光材料

2.7-3μm高功率激光光源在国家安全、生物医学、通讯、远程大气遥感及环境监测等方面具有重要需求，但由于该波段激光器的功率水平普遍较低，其技术水平远落后于可见光或1μm波段激光器。LD泵浦的2.7-3μm波段激光器的实用化发展瓶颈关键在材料。本项目针对目前具有应用潜力和研究基础的掺Er3+倍半氧化物透明激光陶瓷材料作为激光介质,系统研究了分散剂、烧结助剂以及烧结制度等参数对倍半氧化物陶瓷致密化的影响规律。研究发现传统倍半氧化物粉体的分散剂（(NH4)2SO4）虽然能提升粉体的分散性，但是硫元素很难彻底排除。残留的硫元素会导致“光致暗化”以及激光效率的下降。团队采用有机分散剂（PAA）取代传统无机分散剂(NH4)2SO4，实现了高纯度、高分散性倍半氧化物陶瓷粉体的合成。采用合成的倍半氧化物纳米粉体，结合真空烧结以及热等静压烧结工艺，掌握了陶瓷微结构的调控方法，实现了高透过率、低散射损耗、高激光效率倍半氧化物透明陶瓷的制备。其中包括高光学质量Er离子掺杂倍半氧化物激光陶瓷的合成与制备，实现了高功率2.7微米激光输出，室温输出功率突破13.4W，为目前Er离子掺杂倍半氧化物材料获得的国际最高输出功率。同时，团队亦实现了Er:Y2O3陶瓷1.6μm高功率激光输出，激光输出功率达到10.2W。团队掌握了具有自主知识产权的高品质3μm波段中红外激光材料的合成方法。