The Experimental Investigations and Modeling of Copper Ions Diffusion into LiNb O Crystal

The processes of diffusion and drift of copper ions in lithium niobate crystal were investigated after annealing in the presence of copper film deposited on the crystal surface. The optical absorption spectra of the samples were registered in a direction perpendicular to the direction of diffusion at different distances from the crystal edge. The absorption bands of Cu
⁺
(400 nm) and Cue
²⁺
(1000 nm) ions were observed in all annealed samples. The intensity of the bands varies depending on the annealing temperature and the distance from the source of diffusion. The concentrations of copper ions were calculated in accordance with the Smakula-Dexter formula. The depth dependencies of Cu ions concentrations were approximated in the frames of the model taking into account both the diffusion and the drift of Cu ions. The diffusion coefficients determined from the approximations are in good agreement with the ones known from literature.