一种新型含阳离子空位非对称畸变白钨矿结构多钨酸盐Re3+:Na2La(4-x)Bax(WO4)7 (Re=Nd, Yb)自拉曼激光晶体的研究

Crystalline Raman technique can significantly extend the spectral coverage of solid-state lasers, which has important applications in various fields. Searching for good self-Raman laser crystals is consistent with the trend in developing integrated and miniature all-solid-state lasers operating in the new wavelengths, and becomes the research hotspot and difficult point in the related areas. Na2La4(WO4)7 crystal has the incommensurately modulated scheelite-type cation-deficient structure, in which the [WO4] anionic groups exhibit excellent Raman scattering activity. In addition, this crystal has good thermal and mechanical properties which make it possible to be a kind of efficient laser host material. With the idea of combining the good features of Na2La4(WO4)7 and BaWO4, this proposal tent to use the structure-controlled method by adding Ba2+ ions into Nd3+/Yb3+:Na2La4(WO4)7, to improve the Raman properties of [WO4] anionic groups, keeping its excellent physical, chemical and optical characters at the same time. The Czochralski method is chosen to grow the crystals and, the synthesis of the raw materials, growth rate, morphology of the crystal and other factors chich are ralerative with the quality of the crystals will be focused on. The optical spectroscopy properties of Re3+:Na2La(4-x)Bax(WO4)7 (Re=Nd, Yb) self-Raman crystals will be studied by measurements of absorption, emission spectra. Raman characters are revealed from the Raman spectra. How the structure affects the optical and Raman properties will also be calculated and discussed concretely, which is crucial to determine the amount of Ba2+ ions in the crystal. Results and knowledge arising from the proposal research will also contribute to the pursuit of new prominent self-Raman laser crystals.

晶体拉曼激光技术是拓展激光波长覆盖范围的有效手段之一。开发性能优异且适合LD泵的自拉曼激光晶体符合当今新波长全固态激光器集成化、小型化的发展趋势和要求。Na2La4(WO4)7晶体物化性能和机械性能优良,具有特殊的含阳离子空位非对称畸变白钨矿结构，其[WO4]阴离子基团呈现出优异的拉曼活性，是一种极具研究价值的激光晶体基质材料。本项目以Re3+:Na2La(4-x)Bax(WO4)7(Re=Nd,Yb)自拉曼激光晶体为研究对象，通过对晶体的结构进行分析与计算以及对晶体原料的合成、生长、光谱与拉曼特性和自拉曼激光实验等方面的研究来揭示Ba2+离子对结构和自拉曼性能影响规律与机理，从而达到通过Ba2+含量对晶体进行结构调控与优化，使激活离子的光谱性能和[WO4]基团的拉曼性能达到最佳，实现1.1-1.5μm波段自拉曼激光输出，开发出性能优异且具有自主知识产权的自拉曼激光晶体的目的。

近年来，随着半导体激光器和拉曼激光技术的迅速发展,LD泵浦的全固态自拉曼激光晶体成及其器件的开发利用成为了高新技术及其相关产业的一个重要发展方向。白钨矿结构的钨酸盐Na2La4(WO4)7晶体具有良好的光学性能、机械新能和热学性能，其特殊的局部无序结构能够为晶格中的发光中心提供合适的晶体场环境，因此当稀土元素作为激活离子进入晶格后往往具有较好的光谱性。此外，[WO4]被证实具有较好的拉曼性能，其与稀土离子发光中心相互作用，可能对输出波长起到调节作用，实现新的激光波长。.在此想法的基础上，本项目围绕具有特殊无序结构的Na2La4(WO4)7为基础，合成了一系列Re3+:Na2La4(WO4)7多晶粉末，研究了性能与掺杂离子种类和浓度的对应关系，确定了各离子的最佳含量范围；研究晶体的结构及其对稀土掺杂离子发光性能的影响，获得晶体结构与光学性能之间的相互关系；采用提拉法晶体生长实验，探索出了一套生长工艺参数并获得了较高质量的Re3+:Na2La4(WO4)7(Re=Nd,Yb,Er,Ho)晶体，继而测试并分析了晶体的光谱性能；分析了晶体的热透镜效应及其对激光性能的影响，提出了针对性策略，为后续的激光实验提供了有用了理论支持；开展了激光实验，实现了LD泵浦的近红外波段不同波长的W级激光输出。.此外还研究了具有特殊无序结构的Re3+:KBaLn(MoO4)3(Re=Nd,Yb,Er;Ln=Y,Gd)晶体的生长、结构和光谱性能，揭示了结构与性能之间的关系，设计了激光腔型和光路，开展了激光实验，获得了W级别近红外连续波长激光输出。.研究了熔盐法生长具有单斜结构的Er3+:KLu(WO4)2晶体和Er3+/Pr3+:KLu(WO4)2晶体，测试并详细分析了晶体的光谱性能，采用J-O理论计算并分析了晶体的重要光谱参数，并根据实际光谱性能设计谐振腔型，采用合适的散热装置和适当的镀膜，成功的获得2.7μm中红外激光输出。.本项目在执行期间共发表相关研究论文12篇，培养毕业硕士3名，完成预定的目标。