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Abstract: Five absorption bands, at 227, 300, 340, 370 and 457nm, were observed in the optical absorption spectrum of Ce:Y3Al5O12 (Ce:YAG) crystals grown by the temperature gradient technique (TGT). The absorption bands at 227, 340, and 457nm were identified as belonging to the Ce3+-ion in the YAG crystal. A near UV optical emission band at 398nm was observed, with an excitation spectrum containing two bands, at 235 and 370nm. No fluorescence was detected under 300nm excitation. The pair of absorption bands at 235 and 370nm and the absorption band at 300nm were attributed to the F- and F+-type color centers, respectively. The color centers model was also applied to explain the spectral changes in the Ce:YAG (TGT) crystal, including the reduction in the Ce3+-ion absorption intensity, after annealing in an oxidizing atmosphere (air). [Copyright &y& Elsevier]

Abstract: Yb: YAlO3 (YAP) (15at%) and Yb: Y3Al5O12 (YAG)(15at%) have been grown using the Czochralski method. Their absorption and fluorescence spectra were measured at room temperature and important spectroscopic parameters were calculated. Through the comparison of spectroscopic parameters of Yb:YAP and Yb: YAG, all results indicate that 15at% Yb:YAP crystal is a potential candidate used for compact, efficient thin chip lasers when the laser output wavelength is 1012 or 1038nm. [Copyright &y& Elsevier]

Abstract: Undoped LaAlO3 and Ce-doped LaAlO3 single crystals were grown by the Czochralski process. The segregation coefficient of cerium ions in 1at% Ce: LaAlO3 is 0.28. The undoped LaAlO3 and Ce-doped LaAlO3 single crystals were characterized by infrared transmission spectra and ultraviolet/visible/near-IR absorption spectra. It was observed that the band-to-band absorption of LaAlO3 host is around 209nm. Four characteristic f–f transitions of Ce3+ ion at 1923, 2354, 2669, and 3728cm-1 and five f–d transitions around 198, 206, 214, 246, and 316nm in the Ce-doped LaAlO3 crystal were observed. Strong emission around 410nm was also observed at excitation of 317nm in the Ce-doped LaAlO3 single crystal. [Copyright &y& Elsevier]