Cr^(4+):Ca_2GeO_4激光晶体生长及结构表征

采用助熔剂法,以CaCl2为助熔剂,生长Cr4+:Ca2GeO4新型近红外可调谐激光晶体.通过X射线衍射(XRD)、激光Raman光谱、X射线光电子能谱(XPS)等方法对晶体进行结构表征.结果表明,得到的晶体为单斜晶系镁橄榄石结构的低温γ-Cr4+:Ca2GeO4单晶,晶格参数为a=5.3209(1=0.1nm),b=6.6648,c=11.2606.Raman光谱测试证实了晶体中存在锗酸根离子,并对其进行了振动归属.XPS分析结果表明晶体中的Cr元素是以Cr4+的形式存在的,不含有其他价态的Cr离子。

Highly efficient CW laser operation in 4 at. % Tm^(3+) and 4 at. % Y^(3+) codoped CaF_2 crystals

Tm：CaF2 and Tm;Y：CaF2 single crystals were prepared by the temperature gradient technique. The spectral properties of Tm;Y：CaF2 single crystals were investigated and compared with those of Tm：CaF2. It was demonstrated that codoping with Y3＋ ions could efficiently improve the spectroscopic properties. Tm;Y：CaF2 crystals have larger absorption cross-sections at the pumping wavelength, larger mid-infrared stimulated emission cross-sections, and much longer fluorescence lifetimes of the upper laser level（Tm3＋：3H4 level） than Tm：CaF2 crystals. Continuous-wave（CW） lasers around 1.97 μm were demonstrated in 4.0 at. % Tm,4.0 at. % Y：CaF2 single crystals under 792 nm laser diode（LD） pumping. The best laser performance has been demonstrated with a low threshold of 0.368 W, a high slope efficiency of 54.8%, and a maximum output power of 1.013 W.

Cr,Ca∶Y_3Al_5O_(12)晶体中四配位四价铬离子激光中心的形成

在以中频感应提拉法生长Cr，Ca∶Y3Al5O12晶体的基础上，根据不同Ca／Cr掺杂浓度比的晶体于空气中退火前后的吸收光谱数据，建立了四配位四价Cr激光中心形成的缺陷反应方程，认为Cr3+到Cr4+的价态转变与晶体中带有两个而不是一个正电荷的氧离子空位有关。

Single Crystal Growth and Laser Action of Chromium- Manganese Codoped Zinc Tungstate

The spectroscopic and laser properties of zinc tungstate doped with Cr ion at room temperature and low temperature have been studied by several scientists.ZnWO4:Cr3+ CW laser output has been obtained at 77 K.After annealing in sol-