长周期光纤光栅在地震检波器中的应用.doc

长周期光纤光栅在地震检波器中的应用摘要:地震方法是地震勘探中相当重要的一部分，而地震检波器是地震勘探中最重要的环节，其性能直接影响到地震勘探的精度。基于长周期光纤光栅能透射特定波长、无后向反射等优点，本文提出了一种新型的长周期光纤光栅地震检波器系统。本文以长周期光纤光栅相位匹配条件为基础，推导出了长周期光纤光栅地震检波器的灵敏度公式。并通过牛顿第二定律建立了长周期光纤光栅检波器的力学模型，推导出了地震检波器的传递函数。最后，利用实例仿真得到了该长周期光纤光栅地震检波器系统的幅频特性曲线图，并通过模拟仿真证明了长周期光纤光栅用于地震检波器的可行性。而且通过改变光纤的长度、质量块的质量、阻尼系数等参量可以得到很好的频率特性与灵敏度，这为提高该系统的性能指明了方向。关键词:长周期光纤光栅；耦合理论；地震检波器；传递函数；幅频特性LongperiodfibergratingisusedinthegeophoneAbstract:Seismicexplorationmethodisanextraordinaryimportantportionoftheseismicexploration,whileseismicgeophoneisthefirstlinkinthenormalworkingofseismicexplorationinstrument.Theperformanceoftheseismicgeophoneinfluencesthewholeseismicexplorationtechnology.Basedonthenarrowbandtransmissionandfreeofbackreflectionfeaturesoflongperiodfibergrating,anewtypeoflongperiodfibergratings(LPFGs)geophoneispresentedinthispaper.Thesensitivityofthelongperiodfibergratinggeophonesystemisdeducedwiththephasematchingoflongperiodfibergratingaspreconditions.ThemechanicmodelofthelongperiodfibergratinggeophoneisestablishedbyNewtonlaws,andthetransferfunctionofthegeophoneisdeduced.Theamplitude-frequencycharacteristicsofthelongperiodfibergratinggeophoneisachievedanditsfeasibilityisprovedbysimulatingasimpleexample.Theproperfrequencyfeatureandsensitivitycanbeachievedbychangedthelengthofopticalfiber,themassofmassblockandthedampingfactor,whichpointsanewwayforimprovingtheperformanceofthissystem.Keywords：Longperiodfibergrating;Couplingtheory;Geophone；Geophonetransferfunction;Amplitude-frequencycharacteristic目录TOC\o"1-3"\h\z\uHYPERLINK\l"_Toc294108320"第一章绪论PAGEREF_Toc294108320\h1HYPERLINK\l"_Toc294108321"1.1地震勘探技术及应用PAGEREF_Toc294108321\h1HYPERLINK\l"_Toc294108322"1.2光纤地震检波器的研制