新型中/低对称性钼酸/硅酸盐晶体双波长激光性能研究

All-solid-state dual-wavelength lasers have attracted considerable attentions for numerous application，such as detection, laser display, nonlinear frequency conversion and so on. This project emphasized on near-infrared dual-wavelength laser output of Nd:LiGd(MoO4)2 and Nd:LYSO crystal with intermediate/low symmetry. Crystal structure, spectral properties and space asymmetry are studied. And on this basis the possible applications will be explored. In this project, our aim wavelengths are dual-wavelength laser output based on energy spilitting and stimulated raman scattering, include 1.061um+1.068um、1.075um+1.079um and Stokes output of different raman shifts on Mo-O bond, emphasised on the combination of different components within the 4F3/2→4I11/2 transition and raman spectra characteristics of Mo-O bond. After the dual-wavelength lasers have been realized preliminary, the corresponding parameters will be optimized. The aim of this project is to provide a reference and guidance for other low symmetry crystals, because Nd:LiGd(MoO4)2 and Nd:LYSO are two representative crystals with intermediate/low symmetry.

双波长激光输出在检测、激光显示、非线性频率转换等众多领域具有重要的研究意义与应用价值。本课题选取中对称性晶体Nd:LiGd(MoO4)2和低对称性晶体Nd:LYSO作为研究对象，通过对其结构与光谱性质的研究，分析并利用其物理性能的空间不对称性，并在此基础上探索晶体在双波长激光输出方面的应用。在此项目中，我们力争实现以能级分裂为主，受激拉曼散射为辅的方式，侧重Nd3+中4F3/2→4I11/2分量之间的跃迁组合以及Mo-O键的拉曼光谱特性，设计和优化波长为1.061um+1.068um、1.075um+1.079um和Mo-O键不同拉曼频移，各阶Stokes输出等双波长激光输出，并探索和开发这些波长的实际应用。由于这两种晶体是中/低对称晶体的代表，我们同样期待我们的研究工作能够为此类相关晶体在双波长输出方面的研究提供借鉴与指导。

钼酸盐晶体和钨酸盐晶体是非常重要的激光晶体和激光自拉曼晶体。本项目针对新型的钨酸盐晶体Nd:Bi2Mo2.66W0.34O12的生长、光谱、受激发射截面、荧光寿命、拉曼频移、激光性能等进行了研究；首次采用顶部籽晶法生长了Nd:Bi2Mo2.66W0.34O12晶体，并发现该晶体在808nm处的吸收带的半峰宽非常大，达到13nm；荧光寿命为118us；测得了自发拉曼光谱并计算了拉曼增益系数，并首次实现了该晶体的激光输出，对应的光光转换效率为17.4%，斜效率21.6%。考虑到该晶体强烈的拉曼特性，Nd:Bi2Mo2.66W0.34O12晶体有望实现激光自拉曼。对于钼酸盐晶体Nd:LiGd(MoO4)2，我们对其激光性能的各向异性进行了表征；计算了1061 nm和1068 nm这两个波长在主轴方向的受激发射截面，给出了这两个波长的受激发射截面的空间分布，研究了不同切向Nd:LiGd(MoO4)2晶体激光输出的各向异性，找到了双波长比例相近时的切割角度，提出了采用晶体各向异性来控制波长发射的新思路。