Abstract

Moustafa Hussein Aly
Evaluation and Performance Enhancement for Accurate FBG Temperature Sensor Measurement with Different Apodization Profiles in single and Quasi- Distributed DWDM Systems
In thiswork,differentFBGtemperaturesensorsaredesignedandevaluatedwithvariousapodization profiles. Evaluationisdoneunderawiderangeofcontrollingdesignparameterslikesensorlengthand refractiveindexmodulationamplitude,targetingaremarkabletemperaturesensingperformance.New judgment techniquesareintroducedsuchasapodizationwindowroll-offrate,asymptoticsidelobedecay level,numberofsidelobes,andaveragesidelobelevel.Evaluationtechniqueslikereflectivity,FullWidth at HalfMaximum(FWHM),andSidelobeSuppressionRatio(SLSR)arealsoused.Forasingleaccurate temperaturesensormeasurementinextensivenoisyenvironment,optimumresultsareobtainedbythe Nuttallapodizationprofile withalengthof19mmandarefractiveindexmodulationamplitudeof 4104. TheNuttallapodizationprofile achievesahighreflectivity of97.97%,anarrowFWHMof 0.2135nm,averylowsidelobe-strengthof 89.71dB,averylowsidelobeaverageof 90.79 dB,and finally averyhighSLSRof89.62dB.Foraquasi-distributedFBGtemperaturesensorinextensivenoisy environment,optimumresultsareobtainedbytheNuttallapodizationprofile withalengthof10mm and refractiveindexmodulationamplitudeof2.6104. Itachievesanacceptablereflectivity of51.43%, a narrowFWHMof0.1985nm(lessthan25GHZ),averylowsidelobestrengthof 100.94dB,averylow sidelobe averageof 121.74dB,averyhighSLSRof98dBandahighmainlobeslopeofabout73.5 dB/nm. Thesesatisfactoryresultsofbothcasescameontheexpenseofroll-offratethatisturnedoutto be low.Nuttallapodizationisusedtoconstructanoptimumandreliablequasi-distributedtemperature sensing systemthathasanadjacentchannelisolationofmorethan17dBat0.4nmchannelspacing, which issuitableforDWDMsensingsystems