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Float zone growth and spectral properties of Cr,Nd:CaREAlO4 (RE=Y, Gd) single crystals for potential use in solar-pumped solid state lasers

Aki Ueda 1Mikio Higuchi 1Daiki Yamada 1Sho Namiki 2Takayo Ogawa 2Satoshi Wada 2

1. Hokkaido University, Sapporo 060-8628, Japan
2. RIKEN, Wako 351-0198, Japan



   Solar-pumped lasers have recently been attracted much attention from the viewpoint of suitable energy development. In previous studies, Cr,Nd:CaREAlO4was developed as a host crystal for the Nd-lasers, but there have no reports on the crystal growth and spectral properties of Cr- and Nd-codoped CaREAlO4. Since CaREAlO4 does not have any tetrahedral site, spectral drawbacks found in YAG may be improved. In this study, we grew Cr,Nd:CaREAlO4(RE=Y, Gd) single crystals by the floating zone method and investigated their spectral properties.

   A ceramic feed rod with a composition of CaRE1-xNdxAl0.999Cr0.001O4where x=0-0.01 was used for the single crystal growth by the floating zone method. Crystals were grown with conditions of growth rate: 2.5-5mm/h, atmosphere: air, CO2 or O2, rotation rate: 30-60 rpm.

   The grown single crystals were transparent and deep red in whole. A lower growth rate of 2.5 mm/h and a higher rotation rate of 60 rpm were effective to suppress the formation of voids.

   Cr,Nd:CaYAlO4showed strong absorption in the wavelength region of 320-600 nm. The absorption cross section of σ-polarization at 430 nm, where Cr,Nd:YAG has the maximum absorption, is about 862 ×10-20 cm2, which is 120 times as large as that of Cr,Nd:YAG. Cr,Nd:CaGdAlO4 also showed strong absorption in the wavelength region of 340-600 nm. Although the absorption cross section of Cr,Nd:CaGdAlO4 was less than that of Cr,Nd:CaYAlO4, the absorption peak was shifted to the longer wavelength of 470 nm. By pumping at 400 nm, Cr,Nd:CaYAlO4 showed strong fluorescence bands around 900 nm and 1080 nm by Nd3+. This result indicates that the energy absorbed by Cr3+ is effectively transferred for Nd3+in these crystals, and Cr,Nd:CaREAlO4single crystals are therefore one of the promising materials for solar-pumped solid state laser systems.


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Related papers

Presentation: Poster at 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17, Topical Session 6, by Aki Ueda
See On-line Journal of 17th International Conference on Crystal Growth and Epitaxy - ICCGE-17

Submitted: 2013-03-29 02:26
Revised:   2013-05-14 04:34