作为精密测量仪器光源的微片固态激光器几项关键技术研究

Laser sources are the core technology of high precision measuring instruments. However, during the research, some key fundamental problems of theories and technologies in Nd:YAG and Nd:YVO4 microchip lasers have become the bottleneck in the usage of solid-state microchip lasers in high precision instruments. This research aims at providing laser sources with high precision, high stability, small volume, low power consumption and long lifetime as the light sources in high precision instruments. .(1) The transverse and angular drifts of the end-pumped microchip lasers lead to the instability and inhomogeneity in laser output. In this research, the micro-mirror cavities are studied to restrain the high order transverse modes, The laser diode side-pumping scheme is employed to eliminate the drift of laser properties brought by the pumping drift..(2) The unique relaxation oscillation phenomena in solid-state lasers can be applied to amplify the signal, but at the same time, the noises will be introduced and the measuring speed is limited in instruments. By choosing proper laser crystals and optimizing the doping concentration and pumping level, the relaxation oscillation frequency can be shifted beyond the range of Doppler frequency shift and the noises can be eliminated..(3)In order to meet the requirements of the frequency stability in dual frequency lasers which is 0.1MHz by the academia and industrial production (0.5MHz now), proportional integral differential closed loop control system is used to control the phase differences..(4) Theoretical analysis and experiments are carried out to pick up the frequency stabilization scheme suitable for the microchip lasers, to make the frequency stability reach the scale of 10-8..Achievements: 6 SCI.thesis, 3 invention patents, lasers which can reach the technical requirements.

激光光源是高精度测量仪器最核心的技术。但发现，Nd石榴石，钒酸钇等微片激光器的几个关键基础性的理论和技术成了用它于高精度仪器上的瓶颈。本项目将为精密测量仪器提供高精度、高稳定、小体积、低功耗，长寿命的激光源打好基础。.⑴端面泵浦的微片激光器光束横向和角向漂移严重，光束截面上的光强欠均匀。拟制作百微米直径的微腔镜压制高阶横膜、并采用侧向泵浦，消除微片激光束方向漂移。.⑵微片激光器特有的弛豫振荡利在对信号有放大，弊在其引入噪声并限制仪器的测量速度。选择激光晶体、优化掺杂浓度和泵浦水平，把微片激光的弛豫振荡频率移到多普勒频移之外，并消除噪声。.⑶为满足国内外对双频激光器频差稳定度0.1兆赫的要求（目前0.5兆赫），采用微分闭环控制系统控制微片激光器的频率差漂移。.⑷理论分析实验，筛选出适合微片激光的频率稳定方式，使其频率稳定达到~10-8。.文章6，发明专利3。结题技术指标见文内。

本国家自然科学基金项目(61775118)研究了Nd:YVO4微片单频激光器和Nd:YAG微片双频激光器性能的关键技术，取得系列成果。项目组还将这两种激光器做光源分别建成激光回馈实验系统和双频激光干涉实验系统，证明了微片激光器有光明的应用前景。 .课题研究的几项关键技术，包括：实验，分析，比较了端泵，侧泵，等的研究结果，并创新的提出了“微片激光器微腔镜+回馈腔中透镜“结构，有效的减小了光束的漂移和发散角，解决了长期困扰的回馈镜变向正交偏振光条纹的相位差跃变问题；研究了微片激光器特有的弛豫振荡频率的控制，可以得到频率在1MHz 到 8MHz之间弛豫振荡；构建了以温度稳定为手段的频率稳定系统，解决了激光回馈过程光强周期变化的频率稳定问题；构建了微片激光回馈位移测量的原理样机，取得满意的可以走向应用的结果；研究了Nd:YAG微片双频激光器的材料（Nd:YAG）自己频差的产生和雕刻频差的产生两种机制，并持续研究了使微片产生双频和控制频差的方法，并用这两种形成机制的频差构建了Nd:YAG微片双频激光干涉仪，证明了这一微片激光器具有很好的应用价值和实现固体微片激光干涉仪的可行性。 .培养博士1名（蔡婷），硕士研究生9名（马响，宋建军，汪晨旭，王琦，缪鑫，袁春宁，王健，陈伟光，陈浩楠），其中已毕业硕士4名。发表标注本项基金号的文章7篇，出版专著两部。专著《不创新我何用，不应用我何为：你所没有见过的精密测量仪器》（张书练，北京：清华大学出版社，2021，03）列出了本项目申请人完成的全部国家自然科学基金的名称和项目号，总结了近40年申请人课题组创新性的工作。这一专著正在译为英文（施普林格要求），将对国内外研究产生重要影响。