Stucture And Properties Of Cu-Doped Lithium Niobate Crystals With Varied Cu Concentration

Congruent Lithium Niobate crystal with Cu doped (Cu: CLN) were grown by Czochralski method with proper temperature field, suitable temperture gradient and right technology paramter. Cu: CLN with no macroscopic defects and good optical homogenization were poled.By Infrared spectrum, UV-Visable spectrum, model of defects in crystal structure, the occupy mechanism of dopants has been studyed. The result showed process of Nb_Li⁴⁺ replaced by Cu²⁺ was the first process, but process of Li⁺ replaced by Cu²⁺ was a essy process, and the latter happened in all doped concentration , and different perform with defferent dope concentration. The (OH-) absorption spectrumof CLN with 5mol% doped Cu²⁺ doped concentration has no different with CLN, so process of absorption Nb⁵⁺ was hard to happen although a lot of dopants.By X ray diffraction and calculus with computer, the proportion between the Nb_Li⁴⁺ replaced by Cu²⁺ and Li⁺ or V_Li^- replaced by Cu²⁺ has been confirmed. The proper doped consistence could make the crystal has the lowest defect density. The treatment of oxidation and reduction could improve defect in crystal, and effect of reduction was clearer.The holographic storage and photorefractive resistance property of crystal was studied by two beam coupling experiment and faculae distortion experiment. The photorefractive of crystal was best when dope consistence was 0.5mol%, more or less could make the photorefractive of crystal reduced. The photorefractive resistance of crystal was descent with dope consistence, and that showed Cu doped was photorefractive enhanced dope. The treatment of oxidation and reduction could make write time shorter, diffraction efficiency higher, and effect of oxidation was clearer.