aINESCTEC,RuadoCampoAlegre,687,4169-007Porto,Portugal
bDepartmentofPhysicsandAstronomy,FacultyofSciencesofUniversityofPorto,RuadoCampoAlegre687,4169-007Porto,Portugal
cCentrodeCompetênciasdeCiênciasExatasedeEngenharia,UniversidadedaMadeira,Funchal,Portugal
dDepartmentofAppliedPhysicsandElectromagnetism,UniversityofValencia,Spain
a r t i c l e i n f o
Articlehistory:
Received4March2015
Receivedinrevisedform20August2015 Accepted8October2015
Availableonline22October2015
Keywords:
Magneticfieldsensor Passiveinterferometer Virtualinstrumentation Magnetostrictivematerial Erbiumdopedfiber Fiberopticlaser
a b s t r a c t
Anerbiumdoped(Er3+)fiberopticlaserisproposedformagneticfieldmeasurement.ApairofFBGs gluedontoamagnetostrictivematerial(Terfenol-Drod)modulatesthelaserwavelengthoperationwhen subjecttoastaticoratimedependentmagneticfield.Apassiveinterferometerisemployedtomeasurethe laserwavelengthchangesduetotheappliedmagneticfield.AdataacquisitionhardwareandaLabVIEW softwaremeasurethreephase-shiftedsignalsattheoutputcoupleroftheinterferometerandprocess themusingtwodistinctdemodulationalgorithms.Resultsshowthatsensitivitytovaryingmagnetic fieldscanbetunedbyintroducingabiasingmagneticfield.Amaximumerrorof0.79%wasfound,for magneticfieldshigherthan2.26mTRMS.
©2015ElsevierB.V.Allrightsreserved.
1. Introduction
Fiberopticmagneticfieldsensorshavebeenstudiedoverthe years.Specialinteresthasbeenshowninthehighpowerindustry owing to its intrinsic insulation (silica), immunity to electro- magnetic interference,highdynamic range and bandwidthand possibility to employ remote interrogation [1]. Several sensing mechanismssuchasmagneticfluid,Lorentzforce,Faradayeffect andmagnetostrictiveeffecthavebeenproposedformagneticfield measurement.Thesemethodscanbeusedwithbothconstantand varyingmagneticfields.
Thefirstmechanismwasexploredbycombiningthemagnetic fluid withan optical fiberrefractive index sensor. In thepres- enceofthemagneticfieldtherefractiveindexofthefluidchanges 3×10-4RIU/mT(RIU—RefractiveIndexUnits)at28◦Cfrom0to 70mT[2].
SensorsestablishedontheLorentzforcerequireanothercurrent carryingconductor(fewmilliamps)thatwillexperiencedeforma- tionin the presence ofan orthogonal magneticfield. Although theydonotexperiencehysteresis,thedeformationinducedisvery
∗Correspondingauthor.
E-mailaddress:ivomac88@gmail.com(I.M.Nascimento).
small;in[3]theopticalsensorisaDistributedfeedbacklaser,with aPi-ShiftFBGwritteninEr3+fiber,andthewavelengthchangesare readwithaMichelsoninterferometerwith25mofopticalpath imbalance. Aminimal detected field of1.5T/Hz1/2 was calcu- lated.Anotheralternativereportedconsistsonusinga6cmlong cavitylaserwithonelongitudinalmodeandtwoorthogonalpolar- izations.Measurementofthebeatfrequencybetweenthesetwo polarizationsisproportionaltothelaserbirefringenceandchanges according topressure exerted in thecavity due to theLorentz force.Resultsshowedrelativelygoodlinearityformagneticfields between4and20mT[4].
Faradayeffectisoneofthemostpopularopticalsensingmech- anismsformagneticfield.Itconsistsoflightpolarizationrotation inducedbythemagneticfieldasitpropagatesthroughasensing mediumanditssensitivitydependsonthemediumVerdetcon- stant.Whilestandardfiberopticcanbeusedasasensingmedium toobservetheFaradayeffect,theVerdetconstantofsilicaisvery smallandthewoundingofthefiberaroundtheconductorgives risetolinearbirefringence,furtherdegradingthesensitivity[5].
Aprototypeoperatingat850nmandbasedonaSagnacconfigu- rationwasdevelopedandtestedwhereamaximumerrorof0.2%
wasachievedforcurrentsrangingfrom300to4000ARMSandtem- peraturesfrom40◦Cupto60◦C,satisfying0.5classoperation[6].
Faradaybasedsensorsareaffectedbytheresidualbirefringenceof standardfibers[7],althoughthisproblemhasbeenrecentlyover- http://dx.doi.org/10.1016/j.sna.2015.10.021
0924-4247/©2015ElsevierB.V.Allrightsreserved.
Fig.1. Experimentalsetupincludingthelaser,passiveinterferometerandacquisitionsetup.
comedinstandardfibers[8],analternativesolutionhasbeenthe useofspunfibersoflowbirefringenceorhighcircularbirefringence [9,10].Ontheotherhand,thebulkglassmaterialsaremorerobust andcanhavehigherVerdetconstantsthanfibers.However,fiber alignmentwiththebulkmaterialistricky[11,12].In[11]asensor operatingat820nminacloseloopconfigurationachieveda5.5%
errorunderstableenvironmentalconditionsfrom10A–20kA.
Inthelastcategory,magnetostricitveelementscanbedeposited orgluedtoanopticalfiberstrainsensor.Inreference[13],Terfenol- DisdepositedinanetchedFBG(FiberBraggGrating)with86m diameter, improvingthe sensitivity from 0.386 to 0.95pm/mT.
Adistributedsensor wasalsodeveloped in[14] andconsistsin woundinga standardsinglemodefiberaroundanickelwire.In thepresenceofthemagneticfieldthenickelwirestretchesandthe phaseoftheRayleighbackscatteredlightchangesaccordingtoit.
ApassiveMach–Zehnderinterferometerwitha3×3couplerand anOPDof2m(1mspatialresolution)wasusedtoreadthephase changes.
Inthispaperwepresentanerbiumdopedopticalfiberlaserwith twoFBGswhosewavelengthismodulatedaccordingtotheexter- nalmagneticfield.ThetransducerelementisaTerfenol-Drodthat stretchesbothFBGs,changingthelaseremissionwavelength.This variationisconvertedintoanintensitymodulationattheoutput ofapassiveinterferometerusinga3×3outputcoupler.Thelaser combineshigherSNR(SignaltoNoiseRatio)withnarrowerband- width,enabling,togetherwiththeinterferometricreadoutsystem, ahigherresolutionthanisattainablewithsystemsbasedonthe directmodulationofasingleFBG.
2. Principle
TheimplementedsetupisdemonstratedinFig.1.Thelasercon- sistsoftwo FBGsat1534.17nmwith150pmspectralwidth(at halfpower)and82%reflectivity,andtheotherat1534.21nmwith 160pmspectralwidthand87%reflectivity,writteninsinglemode BoroncodopedPhotosensitivefiberusinga1058nmperiodphase mask.InbetweenthetwoFBGs,apieceof6.8mofFibercoreErbium dopedfiberM-5isusedasthegainmedium,resultingin8mcavity length.
EachFBGisgluedsidebysideintwopoints,distant2cmapart,in aTerfenol-D(compositionTb0.27Dy0.73Fe2)rodhavingadiameter of0.5cmand10cminlength.Thethicknessofthemateriallim- itsthemagneticfieldfrequencyresponseto100kHz.Afunction generator,acurrentamplifierandaninductorareusedtogener- atemagneticfield(ACand/orDCwithamagnetic-currentrelation of12.2mT/A),modulatingbothFBGsandconsequentlythelaser
wavelengthemission.TheACandtheDCmagneticfieldcorrespond tothealternateandconstantfield,respectively.Laseroperationin reflectionispreferablethanintransmissionasnoresidualpump powerispresentintheoutput.
Forthedetectionofthemagneticfieldinducedwavelengthshift, aninterferometricreadoutschemewassetup.Apassiveinterfer- ometer,havingaOPDof3.96mm(OpticalPathDifference)resulting inaspectralrangeof594pmbetweeninterferometricfringesat 1534nmwasbuiltwitha2×2anda3×3couplerattheinput andoutput,respectively,producingthreeoutputswith120degrees phasedifferencebetweenthem,givenby[15]:
Vn=Ai+B.Cos[ϕ(t)+ϕDC−(n−1)]2
3 (1)
wherenistheoutput1,2and3,AiistheDCcomponentobtained whensweepingoneperiodoftheinterferometer,Bisthevisibil- ityofthefringeswhichismaximizedbyapolarizationcontroller (PC),Ø(t)andØDCisthetimevaryingandDCinterferometerphase, respectively.Insuchconfiguration,anychangeinthelaseremis- sionwavelengthresultsinachangeoftheinterferometeroptical outputphase (Ø(t)andØDC)proportionaltotheOPD.Thisway, theinterferometeractslikeawavelength-to-intensitymodulator enablingtotrackthewavelengthchanges,inducedbythemagnetic field,veryaccuratelywithlowcostinstrumentation.
Thisinterferometerhastheadvantageofnotneedinganactive elementtoavoidtotaloutputfading.Therelativephaseofthethree outputsandthesignalprocessingcanalwaysretrievetherelevant outputinformation,independentlyoftherandomdriftoftheinter- ferometer.Nevertheless,theinterferometerdriftismixedwiththe DCphasechanges,alsoaffectingtheoutputintensityandlimiting theapplicationofthisschemetoACmeasurements.Inanycase, magneticfieldmeasurementswereperformedinatemperature- controlledenvironment.
A16bitsanalogue-digitalconverterfromNI(NationalInstru- ments)with305Vresolutionand2Mbpsbandwidthisusedto readthethreeoutputsoftheinterferometerandtheappliedcurrent signaltotheinductor.Inthisway,theuseofvirtualinstrumentation becomes possible,makingit straightforwardto testand imple- ment any signalprocessing algorithm, by simplyadjusting the software,offeringamuchhigherversatilityandscalability.There- fore,totesttheversatilityof virtualinstrumentationsystems,a LabVIEWprogramwasdevelopedtoprocesstheinterferometric signals,andusedtotestandimplement,simultaneously,twodis- tinctivedemodulationmethods.Thefirstone(typeI)ispresented inFig.2andconsistsonperformingderivativesandanintegration asdepicted[15].Theoutputonlycontainsthevariantphaseinfor-
mationandinorderforthismethodtoworkproperlythevalues ofAimustbethesameforthethreeoutputs,whichisachievedby introducinganadjustablegainineachinterferometersignal.
Theotherimplementedalgorithm(typeII)consistsonperform- ingtheArctangentfunctionofthesignalsprovidedbythedetectors [16]:
ϕ(t)+ϕDC=ArcTan
√3(a3V2−a2V3) a3V2+a2V3−2a2a3V1
(2) where˛2=A2/A1 and˛3=A3/A1.Ifthethreeoutputshavethe samegainthen.˛3=1Althoughitispossibletorecoverthecontin- uousphaseinformation,theinterferometerdriftisalsopresentand thismethodalsorequiresanunwrappingalgorithmtocompensate phasechangesoutof±p.
Laseremissionwavelengthistemperaturedependentanditis affectedbytheFBGsresponsetotemperatureandstraininducedby theTerfenol-Drodduetothermalexpansion.Attheoutputofthe interferometerthiseffectwillbemixedwiththerandomdriftofthe interferometerandusingtypeImethodthisDCeffectsareexcluded.
Ontheotherhand,whenusingthetypeIImethodtheoutputwill containthetemperatureeffectbuthavingaslowvariationwhich issimplyremovedbyfilteringtheACresponse.
3. Results 3.1. Laser
Laserspectral widthis measuredbycouplingatunablelaser (100kHz bandwidth)withthe developedone. In thefrequency domain,theconvolutionofbothincoherentsignalsisreadwitha 50GHzphotodetectorandanElectricSpectralAnalyzer.Sincethe tunablelaserisverynarrowwhencomparedtothedevelopedlaser theresultgivesthespectralshapeofthelaser,centeredinthefre- quencygivenbythebeatfrequencyofboth[17].InFig.3itisshown thelaserspectrumobtainedwiththeelectricalspectrumanalyzer.
Aspectralwidthof1.87GHz(14.7pmat1534nm)wasmeasured forapumppowerof560mW,thelaserlinewidthis40timessmaller thanthefringespectrumrangeoftheinterrogationinterferometer assuringadequatesensitivity.Thelinewidthdependenceonpump powerisresidualandthevariationsarenegligiblewithrespectto thefreespectralrangeoftheinterferometer,theslightbenefitsof thelinewdtidthreductionarepartiallyfadedbythereductionof theemittedpower,therefore,thepumplevelhadlittleimpacton thesensorperformance.Duringthefollowingmeasurements,the pumppowerwassetat560mW.
UsingtheThorlabsPM20CHpowermeterthelaserresponsewas characterizedusingseveralpumppowerlevels.Fig.4showsamax- imumlaserpowerof4.7mWfor560mWpumpandathresholdof 50mWforlasing.
Fig.3.Laserspectrummeasuredinanelectricalspectralanalyzer.
Fig.4. Laserpowerinfunctionofthepumppower.
Laserpowerstabilitywasalsomeasuredalongthetimeusinga photodetectorandtheanaloguedigitalconverter.Recordingthe laser power withan acquisition sampling frequency of 10kHz showedthatthelaserhadanoutputpowermodulationbelow1.2%
at50Hzcausedbytheelectronicsdrivingthepumpdiode.Long termpowerfluctuationsofabout4%whereobservedaswell,how- everthedetectionelectronicscompensatesforthisslowvariation.
Fig.5. LaserwavelengthchangewithDCmagneticfieldandintheinsetthematerial responseaccordingtothemanufacture.
3.2. Magneticfieldmeasurement
Severalcontinuouscurrentstepswereappliedtothecoiland thelaserwavelengthchangeswererecordedusingawavelength meter Burleigh WA-1650 (0.5pm resolution). Fig.5 shows the magnetostrictiveresponseofTerfenol-Ddrivingthelaseremission wavelength,thehysteresiscyclewasobtainedwiththreeindepen- denttestswhenthemagneticfieldgoesupanddown.Theerror barscorrespondtothestandard deviationofthethreeindepen- dentmeasurements,andaccountfortherepeatabilityofthesensor, orthemeasurementprecision.Themaximumfluctuationregis- teredwasof4.5pmatB=5.95mTfortheupcurveand10.7pmat B=8.33mTforthedowncurve.Inallcases,themeasurementaccu- racy,givenbythedeviationbetweenthemeasurementpointsand thenon-linearcalibrationcurvewasmuchbetter,corresponding tosmallererrorvalues.Thenon-linearbehaviorofthecalibration curveisintrinsictotheTerfenol-DresponsetoDCmagneticfields, ascanbeseenintheinsetofFig.5,wherearepresentationofthe manufacturerData-sheetisgiven(noticethatanunloadedrodwas used,thereforesaturationisreachedwithanappliedfieldsmaller thantheonepresentedintheinsetofFig.5).Thematerialexpansion inthepresenceofamagneticfieldisnon-linearandindependent ofthenegativeandpositivesignofthemagneticfields.Therefore, whennobiasmagneticfieldisapplied,theapplicationofanAC magneticfieldresultsinaresponsethatisdoubledinfrequency.
Moreover,sincethetransducerisintrinsicallynon-linear,different DCbiasingpointswillresultindifferentsensitivitiestoACfields.
HysteresisisanadditionalproblemforDCmeasurementsthatis overcamewithspecificsetups[18].
Thelaserresponsetoalternatemagneticfields(AC)at20Hzwas characterizedusingdifferentconstantmagneticfields(DC),with thesetuppresentedinFig.1.Theacquisitionsystemwasdefined with10kHzsamplefrequencyandalowpassfilterwith200Hzcut- offwasappliedforeachinputsignal,beforeprocessingthethree outputsoftheinterferometer.TheACRMSvaluewasobtainedafter filteringthedemodulatedsignalwithasecondorderButterworth band-passfilterwitha5Hzbandwidth.
Fig.6showstheRMSACresponseforaDCmagneticfieldof 0mTapplyingdifferentACstepsduring30seach.Theresultswere obtainedwiththe demodulationprocess type IIandthevalues shownin each step correspondtothe averagevalue.Response oftheTerfenol-Dtopositiveandnegativemagneticfieldsisthe same.Sofor0mTmagneticfieldoffset,theACmagneticfieldpro-
Fig.6. StepsofACmagneticfieldswith0mToffset.
Fig.7. TypeIIdemodulationalgorithmresponsetoAC,usingdifferentmagnetic fieldoffsets.
ducesamodulationwhosefrequencyisacquiredattwotimesthe modulationfrequency.Stillwhenamagneticfieldoffsetisintro- ducedthemodulationisthereforeobtainedatthesamemodulation frequency.Takingthiseffectintoaccount,theacquisitionwillbe acquiredattotwotimesthemodulationfrequencywhennobias magneticfieldispresentoratthemodulationfrequencywhena biasfieldisapplied.InFig.6itisshownthatforalternatemagnetic fieldsbelow4.55mTRMSthesensitivityissmall,ontheotherhand, atvalueshigherthan22.54mTRMSitsaturates.
Compilationofthesensorresponseobtainedusingdemodula- tionalgorithmtypeIIwithdifferentDCmagneticfieldsispresent inFig.7.Foreach,twoindependenttestswereconductedandthe resultsshowedgoodagreement.Also,astandarddeviationerrorin eachstepispresent,buttheyaretoosmalltobeobservedintheplot.
AnalyzingtheseresultsweseethatcontrollingtheDCmagnetic fieldoffset(thiscouldalsobedonebyapermanentmagnet)higher sensitivitycanbeobtained,dependingofthemeasurementrange.
Formagneticfieldsupto12.2mTRMS aconstantfieldof4.88mT givesthebestresponse.Ontheotherhand,forvalueshigherthan 12.2mTRMS,aDCmagneticfieldof8.54mTispreferable,measur- ingfieldsupto18.2mTRMS.Moreovertheworstsensitivitieswere foundforaconstantmagneticfieldof0,13.42and16.47mT,which alsocorrespondedtotheworstsensitivityregioninFig.5.
Fig.8. TypeIIdemodulationACsignalsforACmagneticfieldshigherthanthebias field.
Thesamemeasurementswhereperformedsimultaneouslywith thealgorithmI,theplotsobtainedwiththetwoalgorithmswhere indistinguishableandthereforetheresultshavebeennumerically compared.Consideringtheresultsobtainedforeachindependent testmaximumerrors werecalculated andpresentedinTable1.
Thecalculationisdoneconsideringtwotimesthestandarddevi- ationdividedbytheaverageACvalueineachstepforchanging magneticfieldshigherthan2.25mTRMS.Amaximumerrorof1.61%
wasfoundconsideringazeromagneticfieldoffset.Forotheroff- setvaluestheerrorislowerthan0.79%becausethesensitivityis higherforlowACmagneticfields.Also,bothdemodulationsalgo- rithmswerecompared.Althoughthesameresponsewasobtained, theerrorswereslightlylowerusingtypeIIalgorithm,whichmakes useoftheArctangentfunction.Howeveranisolatedcase,forabias of4.88mT,type IIprocessinggavea slightlysuperiorerror.The maximumandminimumimprovementobtainedwithitwas3.02 and0.1%,respectively.Betterresolutionsareingeneralachievedin typeIIthanintypeImethodbecausethelatteroneemploysmore complexfunctionssuchasderivativesandintegration,translating intoincreasednoise.
Fig.8 shows the signals recovered for two particular cases, wheretheACmodulationishigherthanthebiasfield.Itclearly showsthefundamentalfrequencyof20Hzandadistortioninthe lowerpartofthesinusoidalduetotheweekresponseofthemag- netostrictivematerialtolowmagneticfields.AccordingtoFig.5, theregionof0–2mT(fieldgoingdown)andfrom0to3mT(field goingdown)showsverylittleresponse.Thisrangeisabout5mT andjustifiestheflatresponseofthelowerpartofbothcurves.
ThesignaltoNoiseratiowasalsoinspectedbytheFFT(Fast FourierTransform)oftherecovereddemodulatedsignalasafunc- tionofthebiasfieldconsidering20Hzmodulationandbandwidth.
InFig.9itisshowntheFFTspectrumfora0and4.88mTbiasfields.
TheresultsarealsocompiledinFig.10forawiderrangeofbias fields,showingavariationbetween−63and67dBfornon-zerobias fieldswithnodependencewiththeappliedbiasfield.However,the SNRdecreasessignificantly,to−46dBforthe40Hzharmonicwhen nobiasfieldisapplied.
Fig.9.FFToftherecoveredsignalwhenanalternatingmagneticfieldisapplied withabiasfieldof0and4.88mT.
Fig.10.SNRasafunctionofthebiasfield.
InagreementwiththeDCresponseofthelasershowninFig.5, thebestresponseoftheACcurrentsenorisachievedwithalow butnon-zerobiasingfield,howeverthebestlinearityisobtained formoderateDCfieldsbecausethetransducerworksstillfarfrom saturation.ThesetwosituationsarecomparedinFig.11.
Finally, we haveto pint outthe foreseeable thermal behav- iorofthissystem.ThissensorisintendedforACmeasurements, temperatureisaquasi-DCeffectbecauseofitsvariationisslow.
Temperaturehastwoeffects,thefirstoneistheshiftofthewave- lengthemittedbythelaserduetothethermalexpansionofthe transducer,thetypeIprocessingoftheacquiredsignalsmakesup forthisshiftsothattemperaturedoesnotaffectthemeasurement oftheACmagneticfield,thetypeIIprocessingcanremovethether- malshiftbyaDCfilter.Thesecondthermaleffectisthevariationof magnetostrictivestrainwithtemperature;althoughmagnetostric- tivecurvesareverysensitivetostress,ithasbeendemonstrated [19,20]thattheresponseofTerfenol-Disalmosttemperatureinde-
Fig.11.TypeIIdemodulationalgorithmresponsetoAC,usingdifferentmagnetic fieldoffsets.
pendentintherangeof[0◦C,90◦C]forexcitationfieldsbetween 0and40kA/m.Therefore,itisassumedthatthesensorpresented herecouldbereasonablystablewithinthetemperaturerangesand magneticexcitationsmentionedbefore.Thermalcalibrationwould berequiredbeyondtheserangesand thisisa matteroffurther analysis.
4. Conclusion
Amagneticfieldsensorbasedonafiberopticlaserhasbeen proposed.Thelaseremissionwavelengthismodulatedbyamagne- tostrictivetransducerthatstretchestheBraggmirrorsofthelaser.
ThesensorisinterrogatedbyaMatch–Zenerinterferometerwith threeoutputsat120◦,thethreeoutputsareprocessedinrealtimeto retrievethephasevariationinducedbytheACwavelengthshiftgiv- ingastableoutput.Neitherthermalstabilizationofthegratingsnor driftcompensationoftheinterferometerisrequired.Theresponse ofthesensortoACmagneticfieldshasbeenanalysedfordiffer- entstrengthsoftheDCbiasfiled;theperformanceoftwodifferent demodulationalgorithmshasbeencompared. BytuningtheDC magneticfieldfrom0to16.47mTtheACresponseshoweddiffer- entresponses,wherethebestsensitivitieswereachievedfor4.88 and8.54mT.Additionally,lowersensitivitieswereobservedwhen aconstantmagneticfieldof0,13.42and16.47mTwasapplied, correspondingtothelowerandhighersaturationlevelsofthemag- netostrictivematerial.Moreover,amaximumerrorof0.79%was foundforACmagneticfieldsabove2.26mTRMS,withanon-zero biasmagneticfield.Furthermore,comparisonofbothdemodula- tionalgorithmsrevealedthesameresponse,buterrorswerelower inalltestswhenusingtheArctangentfunctionbasedalgorithm.
Themaximumandminimumimprovementwas3.02%and0.1%, respectively.
Acknowledgements
This work was supported by project SMARTGRIDS NORTE- 07-0124-FEDER-000056,financedbytheNorthPortugalRegional OperationalProgram (ON.2-O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European RegionalDevelopmentFund(ERDF),andbynationalfunds,through
the Portuguese funding agency, Fundac¸ão para a Ciência e a Tecnologia (FCT). Ivo Nascimento would like to acknowledge the financial support of FCT (SFRH/BD/80056/2011). J.L. Cruz andM.V.AndrésacknowledgethefinancialsupportoftheMin- isterio de Economia y Competitividad of Spain, Fondo FEDER andGeneralitatValenciana(projectsTEC2013-46643-C2-1-Rand PROMETEOII/2014/072).
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Biographies
IvoM.NascimentowasborninFunchal,Portugal,in 1988.HereceivedhisB.S.degreeinTelecommunications andElectronicEngineerin2009andhisM.S.degreein TelecommunicationsandNetworksintheUniversityof Madeira,Portugal.CurrentlyheisaPh.Dstudentinthe University ofPorto,Portugalandhis presentresearch includesfiberopticalsensorsnamelyforelectriccurrent measurement.
Lasers)attheUniv.ofMinho(1996),M.Sc.inOptoelec- tronicsandLasersatthePhysicsDepartmentofUniversity ofPorto(2000);in2006concludedhis Ph.D.program atUniversityofPortoincollaborationwiththeDept.of PhysicsandOpticalSciencesattheUniv.ofCharlotte, NorthCarolina,USA,withworkinluminescencebased optical fibersystemsfor biochemicalsensingapplica- tionsusingluminescentnanoparticles.Since1997Pedro Jorge hasbeeninvolvedinseveral researchandtech- nologytransferprojectsrelatedtoopticalfibersensing technology,developingnewsensingconfigurationsand interrogationtechniquesforopticalsensors.PedroJorge isaSeniorresearcheratINESCPortowhereheleadstheBiochemicalSensorsteam exploringthepotentialofopticalfiberandintegratedopticstechnologiesinindus- trial,environmentalandmedicalapplicationscoordinatingseveralprojectsinthese areas.Hehasmorethan150publicationsinthefieldsofsensorsinnationaland internationalconferencesandpeerreviewedjournals,isauthorof3bookchapters andalsoholdsonepatent.PedroJorgeisamemberofSPIE.
isresponsiblefortheleadershipandmanagementofthe GroupofFiberOpticsattheUniversityofValencia.He receivedtheB.Sc.andPh.D.degreesinphysicsfromthe UniversityofValencia,Spain,in1979and1985,respec- tively.Since1983,hehassuccessivelyservedasAssistant Professor,Lecturer,andProfessorintheDepartmentof AppliedPhysics,UniversityofValencia,Valencia,Spain.
Afterapostdoctoralstay(1984–1987)attheDepartment ofPhysics,UniversityofSurrey,U.K.,hefoundedtheGroup ofFiberOpticsattheUniversity ofValencia.Hiscur- rentresearchinterestsincludephotoniccrystalfibers, in-fiberacousto-optics,fiberlasersandnewfiber-based lightsources,fibersensors,microwavephotonics,andwaveguidetheory.
