Second Harmonic Intensities and Raman Spectra of New Rare-Earth Doped BiBO₃ Crystals in Glasses

Abstract

New rare-earth doped RE_xBi_1-xBO₃ crystals were successfully prepared through the crystallization of RE₂O₃-Bi₂O₃-B₂O₃ glasses (RE=Y, La, Gd and Yb), and their second harmonic (SH) intensities were examined using Kurtz powder method.It was demonstrated for the first time that BiBO₃ is a nonlinear optical crystal with a phase matchable character and its SH intensity is large, i.e., about 110 times of α-quartz.The incorporation of RE³⁺ into the BiBO₃ phase was confirmed from X-ray diffraction analysis, and it was found that the SH intensities of RE_xBi_1-xBO₃ crystals depend strongly on the species and amount of substituted RE³⁺ for Bi³⁺.In particular, the substitution of Gd³⁺ is very effective in enhancing SH intensity, i.e., about 145 times of α-quartz.The structure of RE_xBi_1-xBO₃ crystals was examined from Raman spectra, and the origin of the optical nonlinearity of RE_xBi_1-xBO₃ crystals was proposed.