Epitaxial growth of Er, Ti doped LiNbO3 films prepared by sol-gel method

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/dm(3) precursor solution containing various Er3+ concentration and 0.10 mol/dm(3) 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. 1.5 mol % Ti : 1.0 mol % Er LN films, which acted as a waveguide, were prepared by our sol-gel method. It showed the 1530nm emission by 980mn excitation, which was considered to be due to the Er3+ corresponding to the I-4(13/2) -> I-4(15/2) transition.