Doped 0.5mol% Er2O3 and (2,4,5,6)mol% MgO in LiNbO3 crystal, Mg:Er:LiNbO3 crystals were grown by Czochralski technique. The IR transmission spectra of those crystals were measured. The OH- absorption peak of Mg(2mol%):Er:LiNbO3 and Mg(4mol%):Er:LiNbO3 at about 3486 cm-1,while that of Mg(5mol%):Er:LiNbO3 and Mg(6mol%):Er:LiNbO3 at about 3535 cm-1. The shifting mechanism of OH- absorption peak was discussed based on the Li-site vacancy model. Using m-line method tested the photodamage of Mg:Er:LiNbO3 waveguide substrate. The photodamage resistant ability of Mg:Er:LiNbO3 is higher than that of Er:LiNbO3. The photodamage resistant ability of Mg(5mol%):Er:LiNbO3 waveguide substrate improves two orders than that of Er:LiNbO3.
Ce:Mn:LiNbO3 crystals with different Li/Nb mole ratios in the melts (Li/Nb = 0.94, 1.05, 1.20, 1.38) have been grown for the first time. The growing conditions varied greatly on the Li/Nb ratio. With the increase of Li/Nb ratio in crystals, the Curie temperature raises while the melting point drops. The infrared spectra of crystals were measured. The exponential gain coefficient, response time and diffraction efficiency were measured by two wave coupling experiments with He-Ne laser (632.8nm). The near-stoichiometric Ce:Mn:LiNbO3 crystal grown from the melt with Li/Nb ratio 1.38 exhibits the largest exponential gain coefficient (33cm-1) and shortest response time (19s), which is attributed to its larger photoconduction. Combined with spectrum analysis we deduced that the increase of photoconduction may be due to the decrease of anti-site (NbLi)4+in crystals.
Potassium lithium niobate doped with CeO2 and CuO, Ce:Cu:KLN crystals were grown by Czchralski method for the first time. The exponential gain coefficient of KLN and Ce:Cu:KLN crystals were measured. Effective charge densities of those crystals were computed. The exponential gain coefficient of KLN and Ce:Cu:KLN crystals are 7.4cm-1 and 4.1cm-1. The effective charge density exponential gain coefficient of KLN and Ce:Cu:KLN crystals are 3.2×1022/m3 and 4.2×1022/m3. The IR transmission spectra of KLN and Ce:Cu:KLN crystals were measured. OH- absorption peak of Ce:Cu:KLN shift red compare to that of KLN. The Raman spectra of those crystals were measured. The Raman spectra of KLN and Ce:Cu:KLN crystals were basically alike, which justified the fact that the ions of impurities entered into the lattice by replacement of original ions of KLN crystals.