High performance widely tunable chromachip lasers

作为“高性能宽调谐色芯片激光器”研究项目的一部分，我们研究了新型固态微芯片激光器和准相位匹配非线性波长转换技术，具体内容如下：（1）利用高浓度Nd掺杂YAG陶瓷，通过晶界控制，实现了高效的激光振荡。通过改变组成结构来控制光谱带宽：Sc部分取代Al的Nd：YSAG陶瓷的增益带宽是Nd：YAG的5倍。(2)提出了一种新的理论模型，该模型通过改变晶体的晶轴取向，在不引入任何其它内光器件的情况下，将晶体的晶轴切向或轴切向，来描述高功率激光器中的热双折射现象<111><110><100>。此外，提出了一种新的降低发热的抽运方法，并得到了实验验证：直接抽运到Nd：YAG激光器的发射能级，提高了抽运效率 ...更多信息 对于低浓度Nd：YAG（1.0-at.%），Nd，通常用于激光器的结构）。我们证明，高Nd掺杂的YAG陶瓷有可能克服这一缺点，确保这种新的泵浦方案的高吸收效率。最后，开发了有限元模拟源代码，估算了发热量及其热问题。(3)我们开发了一种“原位”极化系统，优化了具有高损伤阈值的MgO：LiNbO_3的QPM制备工艺。在此基础上，我们实现了厚度为3 mm的周期极化MgO：LiNbO_3晶体。此外，我们还找到了用d_31（= d_32）代替正常的d_33系数来展宽接收带宽的方法。(4)在该研究项目期间，发表了25篇科学论文和6篇评论论文，在国际会议上发表了33篇演讲，在国内会议上发表了24篇演讲，以及12次特邀演讲。最后，我们获得了4个奖项。少

As part of the "High performance widely tunable chromachip lasers" research project we have investigated new types of solid-state microchip lasers and nonlinear wavelength conversion by the Quasi-Phase-Matching process as follows :(1) We have demonstrated highly efficient laser oscillation using highly concentrated Nd-doped YAG ceramics by grain boundary controlling. The spectrum bandwidth was controlled by changing the composition structure : Nd : YSAG ceramics that have Al sights partially replaced by Sc has 5 times wider the gain band width compared with Nd : YAG.(2) A new model that describes theoretically the thermal birefringence in high power state lasers by changing the orientation of crystal axis from <111> to <110> or <100>-axis cut without any other internal optics into the optical resonator was developed. Moreover, a new pumping method that reduces the heat generation was proposed and experimentally proved.Directly pumping into the emitting level of Nd : YAG lasers improves … More the quantum defect but the absorption efficiency is poor for low concentrated Nd : YAG (1.0-at.% Nd, usually used in construction of lasers). We demonstrated that highly Nd-doped YAG ceramics has the potential to overcome this disadvantage, assuring high absorption efficiency for this new pumping scheme. Finally, simulation source code by FEM that estimate the heat generation and its thermal problem was developed.(3) We have developed an 'in-situ' poling system that optimizes the QPM fabrication process of MgO : LiNbO_3 that is characterized by a high damage threshold. Then we have realized a periodically poled 3-mm thick MgO : LiNbO_3. Moreover, we found the way for broadening the acceptance bandwidth by using d_31 (= d_32) instead of the normal d_33 coefficient.(4) During this research project were published 25 scientific papers and 6 review papers, 33 presentations were given at international meetings and 24 at domestic meetings, as well as 12 invited talks. Finally, we have received 4 awards. Less