掺杂LiNbO_3晶体的光折变性能

PHOTOREFRACTIVE PROPERTIES OF Ce∶LiNbO_3 AND Ce∶Mn∶LiNbO_3 CRYSTALS

在LiNbO3中掺进CeO2 ,MnCO3生长Ce∶LiNbO3和Ce∶Mn∶LiNbO3晶体 ,晶体被极化和还原处理。X射线衍射仪测试晶体的晶格常数 ,采用UV -Spectrophotometer测试晶体的吸收光谱。讨论了掺杂离子对晶格常数的影响、掺杂离子在晶体中的占位及使LiNbO3晶体吸收边发生红移的机理。利用二波耦合实验测试了晶体的指数增益系数、衍射效率和响应时间 ,结果表明 :Ce∶Mn∶LiNbO3晶体的最大指数增益系数达到 2 2cm- 1 ,Ce∶LiNbO3晶体的最大指数增益系数为 17cm- 1 ;Ce∶Mn∶LiNbO3和Ce∶LiNbO3晶体的有效载流子浓度分别为 0 .4× 10 1 5cm- 3和 0 .2× 10 1 5cm- 3;最大衍射效率分别为 85 %和 72 % ;Ce∶LiNbO3和Ce∶Mn∶LiNbO3晶体的二波耦合响应时间分别为 3min和 3.5min。与Ce∶LiNbO3晶体相比 。

DopingCeO2 ,MnCO3inLiNbO3,Ce∶LiNbO3andCe∶Mn∶LiNbO3crystalsweregrownbyCzochralskimethod .Thecrys talswerepoledandreducedtreatment.TheirlatticeparametersandabsorptionspectraweremeasuredbyXRDandUV -Spectropho tometer,respectively .Theinfluenceofdopedionsonlatticeparameters,andthemechanismofoccupyingsitesinthecrystalsand makingabsorptionsideshifttoredbandwerediscussed .Theexponentialgaincoefficient,diffractionefficiencyandresponsetimeof thecrystalswereobtainedbytwo_wavecouplingtechnique.TheresultsshowthattheeffectivecarriesconcentrationofCe∶LiNbO3 andCe∶Mn∶LiNbO3crystalis0 .2× 10 15cm-3and 0 .4× 10 15cm-3,respectively .Themaximumvalueofdiffractiveefficiencyof Ce∶LiNbO3andCe∶Mn∶LiNbO3crystalis 72 %and 85 % ,andresponsetimeis 3 .5and 3minute ,respectively .Comparing with Ce∶LiNbO3,Ce∶Mn∶LiNbO3 crystal is an excellent photorefractive material.