Epitaxial Growth of Er, Ti Doped LiNbO3 Films Prepared by Sol–Gel Method

概要

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Erbium (Er3+) doped lithium niobate (LiNbO3) thick films were deposited on $z$-cut congruent LiNbO3 (LN) substrate by the sol–gel method from the 0.20 mol/dm3 precursor solution containing various Er3+ concentration and 0.10 mol/dm3 poly(vinyl alcohol) (PVA), and their crystal characteristics were evaluated. The Er3+ concentration in the LN film was controlled by the Er3+ concentration in the starting solution. The orientation relationships between Er doped LN films and substrates were determined by X-ray diffraction, Raman spectroscopy, and transmission electron microscopy, and (006) oriented Er doped LN epitaxial layers with parallel epitaxial relationships could be grown on the $z$-cut LN wafer. Moreover, it was made clear from the electron beam diffraction measurements that the film came to be polycrystalline, when the Er concentration was over 3 mol %. The refractive index of Er-doped LN films decreased with increasing Er concentration. $\text{1.5\,mol\,\% Ti}:\text{1.0\,mol\,\% Er}$ LN films, which acted as a waveguide, were prepared by our sol–gel method. It showed the 1530 nm emission by 980 nm excitation, which was considered to be due to the Er3+ corresponding to the $^{4}\mathrm{I}_{13/2} \rightarrow{^{4}}\mathrm{I}_{15/2}$ transition.
2006-09-30