Cu ion in-diffusion in congruent LiNbO3 single crystals

Congruent LiNbO₃ (LN) crystals were grown by Czochralski technique. Thermal in-diffusion of transition metal ion Cu²⁺ into crystal wafers was performed at various temperatures. The absorption peaks in transmission spectra indicates the Cu²⁺ ion diffusion in LN crystal wafer. A broad absorption band centered at 948 nm was observed in the absorption spectra due to the vibronic transition associated with Cu²⁺ centers. The significant red shift in absorption edges indicates the decrease in Li/Nb ratio in Cu in-diffused crystal wafers. Powder XRD of pure and Cu in-diffused LN samples show no structural change during thermal diffusion.