掺钕钨酸钆钠晶体生长、结构及光谱特性

采用提拉法生长了尺寸为φ(30～35)mm×80mm的掺钕钨酸钆钠Nd:NaGd(WO4)2,Nd:NGW]晶体。生长Nd:NGW晶体的最佳工艺参数为:晶体的提拉速率为1～2mm/h,晶体转速为15～18r/min,冷却速率为10℃/h,液面上轴向温度梯度为0.7～1℃/mm。通过热重-差热分析(thermogravimetry-differential thermal analysis,TG-DTA),X射线衍射(X-ray diffraction,XRD)对晶体进行表征。测试了晶体的红外及Raman光谱,分析了晶体的振动模式,并将晶体振动光谱进行归属。由TG-DTA曲线得到晶体熔点为1251.7℃。XRD分析表明:晶体属于四方晶系、白钨矿结构、I41/a空间群,晶胞参数a=0.53213nm,c=1.13070nm。吸收光谱表明:Nd:NGW晶体在805nm附近有较强、较宽的吸收峰,吸收截面积为3.581×10-20cm2,适合于激光二极管泵浦。

GROWTH, STRUCTURE AND SPECTRAL PROPERTIES OF Nd~(3+):NaGd(WO_4)_2 LASER CRYSTAL

Nd:NaGd(WO_4)_2 (Nd:NGW) single crystals with 30-35 mm in diameter and 80 mm long were grown by Czochralski method. The optimal growth parameters of the Nd:NGW crystal are: a pulling rates of 1-2 mm/h, a rotation rate of 15-18 r/min, a cooling speed of 10 ℃/h and an axial temperature gradient on the solid-liquid interface of 0.7-1 ℃/mm. The crystal was characterized by thermogravimetry-differential thermal analysis (TG-DTA) and X-ray diffraction (XRD). The infrared (IR) spectra and Raman spectra of the crystal were measured, and vibration frequencies of IR and Raman active modes for the crystal were assigned. TG-DTA curves indicate that the melting point of the Nd:NGW crystal is 1 251.7 ℃. The XRD analysis shows that the Nd:NGW crystal belongs to a tetragonal system with a scheelite-type structure and a space group I4_1/a, and the lattice parameters of the crystal are a = 0.532 13 nm and c = 1.130 70 nm. Absorption optical spectra of the Nd:NGW crystal show that there is better and wider absorb peak at about 805 nm, and the absorption cross-section of crystal sample is calculated to be 3.581 × 10~(-20)cm~2, which is suitable for laser diode pumping.