基于Dy:Ln2O3-Al2O3体系的微下拉法高通量晶体制备筛选及直接泵浦实现高功效黄光激光的研究

Yellow laser is located in the sensitive band of human eyes, which has found many important potential applications in the fields of biomedicine, laser display and military etc. The visible lasers such as red, green and blue lasers have been achieved through LD pumping and double-frequency techniques, but only yellow lasers can't be realized directly by these methods owing to lack of relative fundamental frequency light. Therefore, we bring forward to Dy3+ activated Ln2O3-Al2O3 binary system crystals to achieve all-solid yellow laser under blue LD pumping directly. This binary system owns the following advantages: high dielectric coefficient, broad band gap, high thermal conductivity, and low maximum phonon energy, etc. Furthermore, bulk single crystals of them are relatively easy to obtain by the micro-pulling-down method and the Czochralski technique because most of the binary system crystals melt congruently. .In this project, firstly, 4f orbital hybridization model is built on the basis of Dy3+ activated Ln2O3-Al2O3 binary system, the crystal structure and elements are designed and the high-throughput crystal growth by using the micro-pulling-down method is carried out, and then their structure and defects analyses, physicochemical and spectral properties characterization are presented. The emphasis is to study on the relationship between the crystal structures and characterizations, and present the theoretical and experimental researches on the energy levels outcoupling by co-doping with other kinds of sensitization ions, and thus regulate the emission peaks and improve the fluorescence quantum efficiency within the yellow emission bands. Next, 2~3 kinds of appropriate crystals are screened and optimized, and the large-sized crystals with high optical quality are obtained by the Czochralski technique. Finally, laser cavity and the coating film parameters are designed and the stable yellow laser with high efficiency is achieved under LD pumping, and further providing foundation for their reality applications.

黄光激光位于人眼敏感波段，在生物医学、激光显示和军事等领域具有重要的应用。通过对LD泵浦的晶体进行倍频已获得红、绿、蓝等可见光波段的激光输出，唯独黄光激光因缺少相应的基频光而无法倍频直接实现。本项目拟采用蓝光LD抽运Dy:Ln2O3-Al2O3晶体直接实现黄光激光。该体系具有介电常数大、带隙宽、热导率高、声子能量低等优点，而且大多同成分熔化，采用微下拉法或提拉法较易获得优质晶体。首先，基于该二元体系构建4f轨道杂化模型进行结构选型和组成设计，然后采用微下拉法高通量制备晶体光纤，研究其结构、缺陷、物化和光谱性能等，重点是研究晶体结构与性能之间的关系，并共掺其它敏化离子进行能级耦合的理论及实验研究，进行量子剪裁，调制黄光峰值波长，提高发光量子效率。接着从中筛选优化出2~3种合适的晶体类型，采用提拉法生长出大尺寸高质量晶体。最后设计激光腔和膜系参数，利用LD泵浦直接实现高效、稳定的黄光激光输出。

全固态黄光激光在激光显示、雷达、生物医学等方面具有重要的应用。本项目以Dy:Y2O3-Al2O3二元体系作为研究对象，高通量制备了Dy3+激活的荧光粉、单晶和混晶等，系统研究其物化、力学、热学、光学、光谱学和激光性能等。本项目的主要研究内容和成果如下：.（1）研究了Dy3+掺杂的YAlO3(YAP)、Y3Al5O12(YAG)、Y4Al2O9和LaMgAl11O19等系列荧光粉的合成和光谱性能。采用高温固相烧结法高通量合成了不同浓度Dy3+掺杂的荧光粉，研究其物相结构和光谱性能等，计算了色度坐标，通过分析比较得出实现黄光发射的最佳掺杂浓度。.（2）研究了Dy3+激活的YAG、(Lu,Y)3Al5O12和YAP等晶体的生长、结构、缺陷、力学性能和光谱性能等。采用提拉法生长获得最大尺寸ф28mm×120mm的高质量Dy:YAG晶体，采用纳米压痕法对晶片的力学性能进行了测试分析，分析了各晶体中Dy3+的浓度效应与荧光动力学，详细研究并总结了晶体的结构与光谱性能的关系。. （3）研究了共掺敏化离子对Dy3+:YAG、Dy3+:YAP和Dy3+:(Lu,Y)3Al5O12等晶体黄光性能的影响。采用提拉法生长了Dy3+与Cr3+、Ce3+、Tb3+、Eu3+、Pr3+、Ho3+等离子分别共掺杂的YAG晶体，以及Dy3+与Tb3+、Tm3+、Yb3+等离子分别共掺杂的YAP晶体等，通过对其吸收光谱、荧光光谱和衰减曲线的测试研究，发现在Dy,Tb:YAG和Dy,Eu:YAG晶体中，Tb3+和Eu3+使得黄光波段的发光量子效率和发射截面增大，在一系列Dy3+:(Lu,Y)3Al5O12混晶中Dy:Lu1.5Y1.5Al5O12具有最大的黄光发射强度，从中筛选优化出Dy,Tb:YAG和Dy,Eu:YAG、Dy:Lu1.5Y1.5Al5O12等晶体为黄光激光增益介质。.（4）研究了Dy3+激活YAG晶体的激光性能。.从生长的晶体中切割加工出多种尺寸的晶体器件，研究其激光性能。利用447nm半导体激光二极管泵浦2at%Dy3+:YAG晶体，获得了中心波长为582.5nm、最大输出功率为166.8μW的黄光激光输出，这是该晶体首次实现连续运转的黄光激光输出。.本项目实施期间在国内外学术刊物上发表论文16篇，授权专利4项，申请国内发明专利2项，培养研究生4名，完成了项目的任务和指标。