| Among the many solid-state laser host materials, the fluoride laser host materials have many advantages that good chemical stability, low melting point, good transparency under high doping concentration, long fluorescence lifetime of spontaneous emission and small affectedness for refractive index by temperature and so on. Therefore, the fluoride laser materials is very important value of research and application in the optical domain.In this paper, Yb:LiYF4 (Yb:YLF) laser crystals were grown by CZ method in Ar and CF4 two different atmosphere. Yb3+ doping concentration is 5%, and the crystal sizes areΦ25×50 mm andΦ25×45 mm respectively. Optimum process parameters the pulling rate was 1 mm/h, the rotation rate was 12 rpm and the cooling rate is 25℃/h. Adopting an annealing process, the cooling rate is 20℃/h, and no crystal cracking phenomenon. By comparing XRD results of Yb:YLF crystals grown in Ar atmosphere and CF4 atmosphere respectively, it is indicated that the crystals grown in CF4 atmosphere has good transparency and high crystal quality. By improving the vacuum, Yb:YLF crystal was grown in CF4 atmosphere. The impurity content of the internal and the surface of crystal was effectively reduced, and the crystal purity was improved. Through the analysis for transition temperature of crystal structure, the component cooling problems of Yb:YLF crystal growth were effectively solved. The spectroscopic measurements of Yb:YLF crystal in CF4 atmosphere is performed:through analysis of absorption spectra parameters, laser transition can be achieved; and the peak of crystal infrared fluorescence spectrum is strongest at 1019 nm, closing to 1030 nm of Yb3+ ions the theoretical value. |
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