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Si

    Si

    oPToELECTRoNICSLETTERSVOI2No.4,15JuI.

    2006

    Thermo-opticallytunablearrayed-waveguide-gratingmadeof

    polymer/Si

    ZHANGHai-ming,MAChun-sheng,QINZheng-kun,LIUShi-yong,ZHANGXi.zhen,

    ZHANGDan,andZHANGDa-mingl,.

    1.StateKeyLaboratoryoRIntegratedOptoelectronics,CollegeofElectronicScienceandEngineering,JilinUniversity,

    Changchun130012,China

    2.JilinNormalUniversity,Siping136000,China

    3.StateKeyLaboratoryoRAppliedOptics,Changctu~JnstituteofOptics,FineMechanicsandPhysics.ChineseAcademyof

    Sciences,Changchun130021,China

    (Received8January2006)

    A33×

    33thermo-opticallytunablearrayed-waveguide-grating(AWG)hasbeenfabricatedbyusingthe

    poly(2,3,4,5,6-pentafluorostyrene-co-glycidyImethacrylate)(PFS-co-GMA).Thetechnologicalprocess

    ofthefabricationofthedeviceisdescribed,andthemeasuredresultsarepresented.Themeasuredspac.

    ingofthewavelengthchanneIisabout0.81nm,the3-dBbandwidthisabout0.35nm.thecrosstalkisa.

    bout20dB,andtheinsertionlossisbetween10.4dBf0rthecentreportand11.9c

    3f0rtheedgeport.

    Themeasuredtherme-opticaltunableshiftisabout

0.12nm/K.Themeasuredcenterwavelengthis

    1545.211551.81nminthetemperaturerangefrom10?

    t065?,andthetuningrangeis6.6nrn.

    CLCnumber:TN252Documentcode:AArticlelD:1673.1905(2006)040243.03

    Inthefuture,opticalcommunicationsystemswilluse moreexceptionalopticalfiberwithhighbandwidth. Densewavelengthdivisionmultiplexing(DWDM)is consideredasapromisingsolutiontothedemandfor transportingterabitsofinformationviafibersc.Arrayed waveguidegratings(AGs)arekeydevicesinDWDM systemsinwhichtheycanserveasmultiplexers,demul

    tiplexersandwavelengthrouters~.

    Gshavebeendevelopedcommerciallyusingvari

    OUStypesofmaterialssuchasSiO2/si,InPandpoly

    merL

    .PolymerA?rGdevicespossesssomeexcellent

    particularfeaturesincludingeasierfabrication,easier controloftherefractiveindex,bettertransparency,and easierverticalintegrationcomparedwithotherkindsof A?rGmultiplexers[.Thewavelengthbandsusedin DWDMsystemsaremainlywithintherangeof15301

    610nrrLRecently.inordertoincreasetheworkwave

    lengthrangeofG,andsomeresearchgroupshave designedandfabricatedtunableA?Gdevicesusing

    manythermo-opticalmaterials[,.Weusethermo-optic (TO)effectinpolymerwaveguidetoobtainthetun

    abilityofthepolymerAWG.Inourexperiment,inorder todecreasetheinsertionlossofA?rG.weutilizethe

    fluorinatedpoly(2,3,4,5,6-pentafluorostyrene-co-gly- cidylmethacrylate)(PFco_GMA)aswaveguidemate-

ria1.Furthermore,wepresentthedesignparameters,de

    tailsoffabricationprocess,andthemeasurementresults ofthetunablepolymerA?G.

    SupportedbyNationalScienceFoundationofChina (60576045,60507004)

    E-mail:zhanghaimir~l@yahoo.corlx,cn

    ThePFco-GMAischosenasthecladdingmaterial. andthestyrene(St)iSusedtoregulatethePFS-co- GMAtoforlTlthecorematerialwithhigherrefractive index.Fig.1showsthemolecularformulaofthemateri

    a1.Thecorerefractiveindexcanbeeasilycontrolled from1.461to1.555throughregulatingthetoolpercent ofSt.Inthispaper,weselecttherefractiveindexofthe polymerguidecoretobe11.4704,andthatofthe

    polymercladdingsurroundingtheguidecoretobe2

    1.463.Sotherefractiveindexdifferencebetweenthe coreandthecladdingisabout?一(n1n2)/n10.5.

    Basedonthesepolymermaterials,a33×33AWGmul

    tiplexerwith0.8nm(100GHz)channelspacingisde

    signed.TheAGmultiplexerisshownschematicallyin Fig.2,andtheoptimizedvaluesoftheparametersare listedinTab.1.

    3hb.1Optim~aparameterinthedesignofthepolymerAWG Centralwavelength201.550918um

    Wavelengthspacing=0.8nrn

    Thicknessofcore65um

    Widthofcoren5urn

    Refractiveindexofcorenl=1.4704

    Refractiveindexofcladdingn21.463

    Diffractionorderm=56

PitchofadjacentI/Oandarrayedwaveguidesd15.5bLrn

    LengthdifferenceofadjacentarrayedwaveguideAL=59.29bLrr Focallengthofslabwaveguidef7838.22H

    FreespectralrangeFSR27.58nit

    NumberofI/0channels2N—一133

    Numberofarrayedwaveguides2M+1=151

?

    0244?

    12000

    8000

    4000

    O

    4000

    F

    O

    O

    Fig.1MolecularformulaofPFS-co-GMA

    O

    1600080000800016000

    Fig.2SchematiclayoutofthedesignedAWGdevice Theguidecoreisburiedinthecladding.Thesche

    maticdiagramofthefabricationproceduresisdrawnin Fig.3,whichincludes(a)spin-coatingthelowerclad

    dingandcorelayerinturn,(b)depositingmetalmask. (c)photolithography,(d)RIE,and(e)spin-coatingthe uppercladding.Andwespin-coatat3000rmpandther

    mallycurethecorematerialafteraninitialtherrnaIcu

    ringofthelowercladding;andeachcuringofwhichisat

    120?.WeestimatetheoptimizedthicknessoftheAl masktobe50nin.Wedry-etchsquarewaveguidepat

    ternsusingRIEprocess.Inordertoavoidside-etching weselecttheoptimizedvelocityofoxygenflowand etchingpoweras40SIMand40W,respectively. Fig.

    4showsascanningelectronmicroscope(SEM)micro

    graphofaninput-channe1.Thesectionofthischannelis 5×5,whichcorrespondswiththeoreticalvalue. ThepropagationlOSSofa5.7-cm-longwaveguide withidenticalcorediameterismeasuredbyacut-back techniqueE,whichisabout

    Themeasuredtransmission

    AWGispresentedinFig.5.

    thatthecrosstalkisabout

    0.68dB/cmat1550nlTL

    spectrumofthefabricated

    Fromthisfigure,wecansee

    

    20dB.andtheinsertion

    lOSSofourdeviceisbetween10.4dBforthecentral portand11.9dBfortheedgeports,thewavelength spacingisabout0.81nm,andthe3-dBbandwidthisa

    bout0.35niILFig.6givesthenear-fieldphotographof Optoelectron.Lett.Vo1.2No.4

    thedemultiplexingspectrumattheoutputportsofthe outputchannels.Therefore,wecanconcludefromFigs. 5and6thatthepresentedAWGdeviceexhibitsgood transmissioncharacteristics.

    core1ayer

Undercladding

    Silicon

    

    一圈mask

    {??—一??一????一

    (a)

    叵?—??一??—?

    (d)(e)

    Mask

    fol'mat

    BP212

    Core

    Cladding

    Fig.3ProcessstepsofthefabricationofAWG:(a)Spin-coat- ingthelowercladdingando0layerinturn;(b)Depositing metalmask;(c)Photolithography;(d)RIE;(e)Spin-coating theupperdaddin~

    ?4sEMmicrographofaninputchannelwaveguldeafter reactiveo0reetching

    1540154415481552155615601564

    Wavelength(nm)

    Fig.5Measuredtransmissionspectrumofthefabricated AwG.atl8?

    0m加如?

    一?p)暑己芑dsI10一??一暑?暑IJ

Optoelectr~Lett.Vo1.2No.4?0245?

    Wavelength(nm)

    Fig.6Near-fieldphotographofthedemultiplexingspectrumFig.7MeasuredTOtuningchara

    cteristicofthepolymerAWG

    Inourexperiment,themeasuredTOcoefficientofthe fluoroacrylatepolymerwaveguideisequalto1.16×

    10/K,whichismuchlargerthanthatofsilica.There

    fore,theTOeffectofthepolymerAWGismainlydeter

    minedbythepolymerwaveguide.Channelspacingis aconstant.whichisindependentofthewaveguideeffec

    tiverefractiveindexn,soweonlygivetherepresenta

    tivethermalbehavioroftheGatthecentralwave

    lengthointhispaper.TheTOeffectoftheAWGatthe centralwavelengthcanbeexpressedby:

    o?Ldn

    dT

    where?Listhelengthdifferenceofadjacentarrayed waveguide,misthediffractionorder,anddn,/dTisthe TOcoefficientofthepolymerwaveguide.Fromthea

    boveequationwecanseethattheGexhibitsatheo

    reticalnegativewavelength/temperatureshiftrateof

    0.12rim/K.TheTOeffectoftheAWGisinvestigated byplacingtheAWGonathermo-controller.Fig.7 showsthetemperatureeffectontheshiftofthecentral wavelengthoftheGinthetemperaturerangeof 10?;65?.WecanobservethatthepolymerGex

    hibitsalargewavelength/temperatureshiftof6.6nm

    inthetemperaturerangeof10?;65?.i.e.ashiftrate

    of0.12rim/K.

    Insummary,wehavefabricateda33×33thermo-op

    ticaltunablepolymerGdevicethroughRIEproce- ss,ofwhichthecrosstalkisbelow20dB.insertion

    lossisbetween10.4dBand11.9dB,andTOtuning

rateis0.12rim/K.TheGistunedoverawide

    rangeof6.6nmbychangingthedevicetemperature(10

    65?).Currently.wearedevotingourselvestofurther increasetheTOtuningrangeofthepolymerAWGde

    vicetomakethisdevicewithlongerworkwavelength. TheauthorswishtoexpresstheirgratitudetoChang

    chunInstituteofOptics,FineMechanicsandPhysics, ChineseAcademyofSciences(C03Q14Z)fortheirgen

    eroussupporttothiswork.

    ElisToyoda,NOct)a,andAKaneko.,Electron.Left..36 (2003),658

    E2]cDragone,C.A.Edwards,andRC.Kistler,IEEEPhoton. Technof.Left.,3(1991),896.

    L3JCSMa,H.M.Zhang,andD.MZhang,Opt.Oomcrl//.,241 (2004),321.

    E4]w.BGIJo,CS.Ma,andDM.Zhan9.Opt.OocrlTi/n..201 (2002),45

    [5]H.MKim,D.C.Kim,andJS.Kim,J.KoreanPhysSoc.. 38(2001),173

    L6JcL.Callender,JF.Viens,JP.Noad,andL.Eldada,Elec. tron.Left.,35(1999),1839

    [7]K.Geetha,M.Rajesh,andV.PN.Nampoori,J.Opt.A:Pure AppOpt.,6(2004),379

    一?pgjJ1uds0呐一g呐口BJ

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