相位取样型光纤光栅多信道幅频与相频滤波性能分析-(6055)

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1、万方数据AbstractFiberBragggratings(FBGs)arecharacterizedbyflexiblefilteringcapability,a11．fiberconfiguration，lowinsertionloss，andlowcost．Therefore，FBGshavebeenconsiderderasoneofhottopicsaroundtheworld．Thephase—samplingFBGs(PS—FBGs)aretheproductofcontinuousdevelopmen

2、tofFBGstechnology,whichhavenotonlymultiple—channelcombspectra，butalsomoreinnovativefeaturesbymodulatingthephase／theamplitudeoftherefractiveindexofFBGs．Thustheyhaveimportantapplicationsinmanyfieldssuchasfiltering，sensing，dispersioncompensation．Inthisthesis，themul

3、tiple—channelfiltersbasedonthePS—FBGsaredesignedandanalyzed，providingboththeamplitude—frequencyandthephase—frequencyresponseswithnormalbandwidthorflarrowbandwidth．Firstly,thestructureofthesampledFBGsandtheclassicanalysticmodelforthesampledfiberBragggrating(i．e⋯F

4、ourierseriesmodels)arepresented．Then，byusingthetransfermatrixmethod，theinfluencesofthesamplingperiod，thedutycycle，andtheindexmodulation’Schangeonthespectraoftheamplitude—samplingFBGsareinvestigated．Atthesametime，theindexmodulationprocessandtheanalysismethodforPS

5、—FBGsareanalyzed．Secondly,basedonthesimulatedannealingalgorithm，PS—FBGsbasedmultiple—channelfilterswithnormalbandwidtharedesigned．Startingfromdiscreteandcontinuousphase—samplingtheories，theoptimizedphasedistributionsforthediscreteandthecontinuousphase—samplingme

6、thodsareobtainedrespectively,withtheuseofthesimulatedannealingalgorithm．Theamplitude—frequencyresponseforthedesignedmulti—channelfiltershowsgoodconsistencyandhighdiffractionefficiency．The3一dBbandwidthfor9-channelfilterwithdicretephasesamplingand5-channelfilterwi

7、thcontinuousphasesamplingare0．15nmand0．18nm．respectively．Thedelayprofileofeachchannelissubstantiallyflat．Inordertoexpandthephaseprocessingcapabilities，alinearchirpisintroduced．Theresultingdelayprofilehasacertainlinearregion．Byusingnumericalfitting，thedispersionv

8、aluesareestimatedtobe540-570ps／nmand680～720ps／nmforthediscreteandthecontinuousphasesamplings，respectively,whichmightbeusedfordispersioncompensation．Inaddition，the3dBb