双钨酸盐晶体Nd∶NaGd(WO4)2(简称Nd∶NGW)和Nd∶NaLa(WO4)2(简称Nd∶NLW)是一类新出现的比较有前途的激光晶体, 它们属于四方晶系白钨矿结构。根据对称性分类,用商群理论分析了两种晶体的拉曼光谱。此类钨酸盐晶体一个原胞中理论上有36个振动模。使用半导体激光的785 nm波长和Ar +激光的514.5 nm激发, 测得激光光入射方向分别垂直和平行于光轴方向的偏振拉曼光谱(100～2000 cm-1), 并对测得的拉曼峰进行了指认。由于Nd3+离子进入晶体取代离子的半径不同,晶格对Nd3+跃迁影响大小不同, Nd∶NGW和Nd∶NLW的拉曼光谱也表现出了差异性。通过不同激发波长的拉曼谱的比较, 在中间波段发现并确认了几个共振拉曼峰。

Double tungstate crystals Nd∶NaGd(WO4)2(Nd∶NGW)and Nd∶NaLa(WO4)2(Nd∶NLW) belong to the tetragonal space group I41/a, is one kind of very promising laser crystal. In this paper Raman spectra of two crystals were analyzed in terms of group space theory. Thirty-six vibration modes were acquired. Therefore, it has thirty-six free degrees. The number of vibration modes is complied with that of the free degree. The polarized Raman spectra were discerned by using two excitation wavelengths (514.5 nm and 785 nm). Although the structure of them are similar, there was a bit discrepancy between Nd∶NaGd(WO4)2 and Nd∶NaLa(WO4)2 of the Raman spectra corresponding to the radius of Nd3+, Gd3+and La3+. Through the comparison of different wavelength excited Raman spectra ,we also got several resonance Raman peaks.