铌酸锂晶体的研究与分析

铌酸锂晶体的研究与分析I摘要本文基于新型线性电光效应耦合波理论，通过设定超晶格周期极化铌酸锂晶体倒格矢参数，从而弥补双折射时o光和e光折射率不同造成的相位失配。计算有效电光系数，推倒耦合波方程的解析解。并利用matlab进行线性仿真，研究温度，波长，外加电场和晶体占空比变化时对于电光效应中的转换效率的影响。仿真的数值结果表明：随着温度与相位匹配时对应的温度的差值的增大，相位失配量将增加，从而导致转换效率呈峰值逐渐降低的波动形式趋于零，当温度满足相位匹配时转换效率最高；此外晶体极化周期数量的增加，将使得转换效率的波动更加剧烈，其值也降低的更快，波动次数也将增多。改变波长的情况基本类似于温度，仅在波动细节上有细微差距。而电场对转换效率的影响则是成正比的线性关系。此外我们所取的占空比约等于0.25和0.75时将可以使转换效率取到最大值。关键词铌酸锂；电光效应；耦合波；转换效率铌酸锂晶体的研究与分析IIAbstractBasedonthenewwavecouplingtheoryoflinearelectro-opticeffect.BysettingthegratingwavevectorparametersofperiodicallypoledLiNbO3crystal,wecompensateforthephase-matchedwhichiscausedbydifferentindexofrefractionoftheo-rayande-raywhenbirefringencehappens.Wecancalculatetheeffectiveelectro-opticcoefficientofthesystem.Throughtheanalyticalsolutionofthewavecouplingequations,usematlabtodolinearsimulation,andstudyontheinfluenceoftheconversionefficiencyintheelectro-opticaleffectwhentemperature,wavelength,electricfieldintensityandcrystaldutycyclechange.Numericalsimulationresultsshowthat,withtheincreasingdifferencemadebytemperaturewhichcorrespondstothetemperatureandphasematching,theamountofphasemismatchwillincrease.itresultsinanincreaseofphasemismatch,thuscausingtheconversionefficiencytoassumethefluctuatingformtendingtozerowhichthepeakvaluereducesgradually;whenthetemperaturesatisfiesphasematch,conversionefficiencyisthehighest.Inadditionwhenthenumberofthecrystalpolarizationcycleincreases,thefluctuationoftheconversionefficiencywillbemoreviolent,thevaluewillalsoreducefasterandthenumberoffluctuationswillincrease.Thesituationofthewavelengthissimilarwiththetemperature.Thereisjustonlylittlediscrepancyonthefluctuationindetailsoftheconversionefficiency.Buttheinfluenceoftheelectricfieldtotransferefficiencyistheproportionallinearrelationship.Inaddition,whenthedutycycleisequivalenttoabout0.75and0.25,theconversionratecanbetakentothemaximum.KeywordsLiNbO3;electro-opticaleffect;coupledwave;conversionefficiency铌酸锂晶体的研究与分析III目录摘要....................................................................................................................................IAbstract..................................................................................................................................II第1章绪论.........................................................................................................................11.1引言......................................................................................................................11.2电光效应的理论发展............................................................................................11.3研究方向和内容....................................................................................................21.4本章小结................................................................................................................3第2章LiNbO3晶体电光效应理论...................................................................................42.1电光效应基本椭球理论........................................................................................42.2LiNbO3晶体的电光效应......................................................................................62.3周期性极化LiNbO3晶体（PPLN）的制备.......................................................82.4线性电光效应耦合波理论....................................................................................92.5本章小结..............................................................................................................11第3章LiNbO3的晶体结构和性质.................................................................................123.1LiNbO3晶体结构................................................................................................123.2LiNbO3晶体基本性质........................................................................................133.3LiNbO3晶体特点................................................................................................133.4PPLN晶体的应用...............................................................................................143.5LiNbO3晶体Sellmeier方程...............................................................................143.6本章小结..............................................................................................................15第4章系统结构和参数设定...........................................................................................164.1相关参数说明......................................................................................................164.2PPLN结构参数设定...........................................................................................164.3有效电光系数设定..............................................................................................174.4本章小结..............................................................................................................18第5章线性仿真与讨论...................................................................................................195.1温度T的改变对转换效率的影响..................................................................195.2波长的改变对转换效率的影响...................................................................225.3外电场E的改变对转换