Spectral Responsivity of Laser and Optical Fiber Power Meters

1 Page 1 NAT'LINST.OFSTAND&TECH AlllObM0M317 surementServices: MIST eEFERENCE pubucations CalibrationServiceforspectral nist ResponsivityofLaserandOptical-Fiber pubnc^^^^^ PowerMetersatWavelengths 250-53 Between0.4fjimand1.8ixm J... Open at page → 2 Page 2 rhe NationalInstituteofStandardsandTechnologywasestablishedin1988byCongressto"assistindustryin thedevelopmentoftechnology ...neededtoimproveproductquality,tomodernizemanufacturingprocesses, toensureproductreliability . .... Open at page → 3 Page 3 NISTSpecialPublication250-53 ' NISTMEASUREMENTSERVICES: bCalibrationServiceforSpectral ResponsivityofLaserandOptical-Fiber PowerMetersatWavelengths Between0.4(xmand1.8imm JohnH.Lehman Optoelectronics Division Electronics... Open at page → 4 Page 4 NationalInstituteofStandardsandTechnologySpecialPublication250-53 Natl.Inst.Stand.Technol.Spec.Publ.250-53,41pages(Dec.1999) CODEN:NSPUE2 U.S.GOVERNMENTPRINTINGOFFICE WASHINGTON: 1999 ForsalebytheSuperintendent ofDocumen... Open at page → 5 Page 5 Contents Page 1.Introduction 1 2.42164CCalibrationServiceSummary 2 3.DesignPhilosophyandTheory 4 4.MeasurementSystem 8 4.1Hardware 9 4.1.1LightSource 9 4.1.2Monochromator 9 4.1.2.1Gratings 9 4.1.2.2GlassFilters(BandpassF... Open at page → 7 Page 7 CalibrationServiceforSpectralResponsivityofLaserandOptical-FiberPower MetersatWavelengthsbetween0.4//mand 1.8/jm JohnH.Lehman NationalInstituteofStandardsandTechnology Optoelectronics Division 325Broadway Boulder,Colorad... Open at page → 8 Page 8 alsobeincluded. Forsiliconphotodiode-based meters,thewavelengthrangefortheserviceis normally450nmto1000nm,andformetersthatincorporatephotodiodesmadefrom germaniumorindiumgaUivimarsenide,therangeis800nmto1750nm.Ifnecessar... Open at page → 9 Page 9 detectorcaseandwindow \ detectorsurface \ I .aperture cap incomingrays incomingand reflectedrays Figure1.Opticalinputconditions: a.collimated;b.converging; c.divergingfrom fiberconnector. Thecorrectresultsandthepreferred... Open at page → 10 Page 10 700 800 900100011001200130014001500160017001800 Wavelength(nm) Figure2.Absolutespectralresponsivityresults.Thelineisobtainedfromthe monochromator-based measurementsystem(eachdatumspacedat10nm increments).Thesolidcirclesa... Open at page → 11 Page 11 X Figure3.Idealsource. Figure4.Broadbandlampoutput. uniformlyirradiatedbyanidealopticalsource.Theidealsourcehasflux0(X),is unpolarized,andhasinfinitelynarrowbandwidthatwavelength A,(thisisdepictedinFig.3). Themonochromat... Open at page → 12 Page 12 X Figure5.Lampoutput,monochromatof efficiency,0(A,)EO(A,). <E)(X)E(X) z(X-X') / ^ / Figure6.Lampoutput,monochromator efficiency,andslitscattering;0(k)B.^(k), Rotationofthegratingrelativetothemonochromator slitsdetermines... Open at page → 13 Page 13 0(X)ElX)T(X) z(X-X') Figure7.Lampoutput,monochromator efficiency,filterandmirrortransmittance, andsUtscattering;(l>(X)E%X)T(K),z(k-X' ). WeusethetermsintroducedaboveandincludeanothertermXsiinthe measurementequationwhicha... Open at page → 14 Page 14 understandingofwhatisincluded,wewriteasimplifiedmeasurementequationthatisnot onlysuitableformonochromator-based spectralresponsivitybutalsoforthesubstitution(or comparison)metJiod.Inthefollowingdiscussion,subscripttdesig... Open at page → 15 Page 15 lamp NISTreference detector Figure8.Gratingmonochromator-based spectralresponsivitymeasurementsystem. atthepositionof,andnormalto,theplaneofthetestmeter.Thebandpassofthe monochromator islessthan6nm. Apyroelectricdetector... Open at page → 16 Page 16 twogratingsisavailable,dependingonthewavelengthrangeofthedesiredcalibration.The rulingdensityofeachgratingis600lines/mm.Onegratingisblazedat500nmandthe otherat1000nm.Theusefulrangeofthemonochromatorusingbothgratingsis400... Open at page → 17 Page 17 sideview flatmirror Figure9.Geometricalraytracingofinputopticsoutsidethemonochromator inthree orthogonalviews(outputopticsareidentical). Whenlightisreflectedfromthefirstsphericalmirrorandisdirectedoff-axis, aberration is... Open at page → 18 Page 18 4.1.5Data-AcquisitionSystem TheelectronichardwareiscontrolledusingapersonalcomputerbasedonanIntel 80486/120MHzprocessorandaGPIBcard.Communications protocolisbasedonthe lEEE/GPIBinterfacestandard. 4.2Software Thesoftwarei... Open at page → 19 Page 19 4.3.2Performance Pyroelectricdetectorsthataredesignedforradiometricapplicationstypically demonstratespatialuniformityvariationsof±2%,noiseequivalentpower(NEP)ranging from10"^W/Hz^''^(nowindow)tolessthan10"^W/Hz^/^(smalla... Open at page → 20 Page 20 NISTElectricalStandards DigitalVoltmeterandStandardResistor ^ C-seriesCalorimeter 633nm,670nm,850nm,1310nm,1550nm CalibrationReference PyroelectricWedge-TrapDetector Figure12.Pyroelectricwedge-trapdetectortraceability. 4... Open at page → 21 Page 21 power.Inthiscase,fullpowermeansthelampsourceisat150W,aUelectronicsareturned on,thepositioningstagesareinitialized,andthereference-detector thermoelectriccooleris onandisallowedtoachievethedesiredtemperaturesetpoint.Theco... Open at page → 22 Page 22 acompletesetofspectralresponsivitydataforasemiconductor-based powermeterwilltake severalhours. Foreachwavelengthinterval,thedataacquisitionsequenceisasfollows.Lightfrom themonochromator isfirstdirectedatthereferencedetec... Open at page → 23 Page 23 50-),=1/3 ( ^ 5 ^ /=i /=i 40 40 (=1 /=i 40 40) 't^„ILK i=\ /=] reposition 5 \ repeal 40 40 E-*'..E*. ;=1 ;=1 40 40; 't^„E*. /=1 ;=1 + reposition 5 \ repeal 40 40 E-^.E*» (=1 V40 ;=1 40) (10) 400 600 800 1000 Wavelength(n... Open at page → 24 Page 24 ExpressingtheUncertaintyofNISTMeasurementResults"byBarryN.TaylorandChrisE. Kuyatt,1994Edition[13].Toestablishtheuncertaintylimits,theerrorsourcesareseparated into (1)TypeBerrors,forwhichmagnitudesaredeterminedbysubjectiv... Open at page → 25 Page 25 6.1.2TemperatureStability(TypeB) Pyroelectricdetectorshaveastrongtemperaturedependence(forlithiumtantalate thisisnearly0.25%/K)andthereforethereferencedetector,withoutactivethermal stabilization, isthecomponentinthemeasu... Open at page → 26 Page 26 6.1.5Noise(TypeA,n=40) Duringnormalcalibrationateachwavelength,40samplesareacqiiicedfromthe referencedetectorandaveraged.ThisisbasedonthestandarddeviationofthedataXQsi, X0s2,X0s3, ••X0S4OdescribedinDataAcquisition,sectio... Open at page → 27 Page 27 6.2.1MonochromatofErrors 6.2.1.1WavelengthOffset(TypeA,n= 3;TypeB) Worst-caseuncertainty,basedonwavelengthcalibration,canbemeasuredby selectingawavelengthregioninwhichdetectorresponsivity ischangingrapidly.For example,in... Open at page → 28 Page 28 theratiooffilterversusno-filterisHmitedbythelowsignal-to-noise ratioofthereference detector.Filtersareselectedtoniiniini2estrayUghtandthemagnitudeofHght,reflectedby thegrating,thatisanyintegermultipleofthewavelengthofint... Open at page → 29 Page 29 10-^ 10-=' 4 ? 10"^ 4 10" 10-' 10 10-10 4 3 10-11 t- 4 10" 674SiAp nilSiNF / \ / \ 400 500 600 700 800 Wavelength(nm) 900 1000 Figute15.Monochromatorthroughputshownwith674nmdiodelasetinputand background. 6.2.1.3Bandwidth... Open at page → 30 Page 30 outputpolari2ation.Boththereferencedetectorandthetestdetectoraresituatedrelativeto thefinalmirror(seehardwaresection),atanangleofapproximately22°.Theestimatefor theextentofmisalignment(variationfrom22°)isbasedonvisualins... Open at page → 31 Page 31 6.3Optical-FiberConnectorCorrection(TypeA,n= 3) Ateachwavelengthincrementofthespectralscan,theoutputofthetestdetectoris comparedtotheoutputoftheNISTreferencedetector.Thisprocessisrepeatedanumber oftimesforeachdetectorand... Open at page → 32 Page 32 Table3.NISTmeasurementuncertainties. Source TypeB TypeA as(%) Sr(%) Nr Pyroelectricworkingstandard CalibrationwithPrimaryStandard 0.47 Temperatvire stability 0.02 Spatialuniformity 0.30 45 Linearity 0.09 Repeatability 0.... Open at page → 33 Page 33 andapproachesthetheoreticallyexpectedvalueforTJ— \,wheretheabsoluteresponsivity, i/P(currentoutput/opticalinputpower) ,isgivenby —=77—=TJ AWnm P hv 1239.5 (14) forelectroncharge e,Planck'sconstanth,lightfrequencyv,andwav... Open at page → 34 Page 34 8.Conclusion Absolutespectralresponsivitycalibrationoflaserandoptical-fiberpowermeters overthewavelengthrangefrom400nmto1800nmpresentsmanytechnicalchallenges.A single,continuouslyvariablelasersourceiscurrentlynotavailabl... Open at page → 35 Page 35 [11]Weusetxadenamestospecifytheexperimentalprocedureadequatelyanddonotimplyorintend endorsementbytheNationalInstituteofStandardsandTechnology.Similarproductsbyother manufacmrersmayworkequallywell. [12]Day,G.W.;Hamilton,C... Open at page → 36 Page 36 AppendixA.PartsList Weusetradenamestospecifytheexperimentalprocedureadequatelyanddonotimply endorsementbytheNationalInstituteofStandardsandTechnology.Similarproductsby othermanufacturersmayworkequallywell. Monochromator,... Open at page → 37 Page 37 RotaryPositionStage:Therotarystagesupportsoneflatmirrorontheoutputside ofthemonochromator. Thisstagesupportsthefinalmirror,whichdirectslightalternately oneachdetectorinthemeasurementsetup.Themanufacturerspecificationfort... Open at page → 39 Page 39 AppendixB.ExampleCalibrationReport Nisr U.S.DEPARTMENTOFCOMMERCE NATIONALINSTITUTEOFSTANDARDSANDTECHNOLOGY ELECTRONICS&ELECTRICALENGINEERINGLABORATORY Boulder,Colorado80303 ReportofSpecialTest SpectralResponsivity For Op... Open at page → 40 Page 40 FIBEROPTICPOWERMETER Model ,SerialNo. withGeDetector,SerialNo. throughair)wasdirectedalternatelyontothetestmeterandtheNISTtransferstandardwithatwo-positionmirror. Thebeamwasfocused{&=f/4)toadiameterofapproximately2mmatth... Open at page → 41 Page 41 FIBEROPTICPOWERMETER Model ,SerialNo. withGeDetector,SerialNo. a> o </> < 1.0 0.9 0.8 0.7 0.6 ^ 0.5 0.4 0.3 0.2 0.1 0.0 700 800 900100011001200130014001500160017001800 Wavelength(nm) Figure2.Detectorresponsivityplottedas... Open at page → 42 Page 42 FIBEROPTICPOWERMETER Model ,SerialNo. withGeDetector,SerialNo. TableI. Absoluteresponsivity(±2.59%). nm A/W nm A/W nm A/W 750.0 0.1233 1100.0 0.4919 1450.0 0.8525 760.0 0.1312 1110.0 0.5049 1460.0 0.8637 770.0 0.1392 112... Open at page → 43 Page 43 FIBEROPTICPOWERMETER Model ,SerialNo. withGeDetector,SerialNo. UncertaintyAssessment TheuncertaintyestimatesfortheNISTspectralresponsivitymeasurements areassessedusingNISTTechnical Note1297,"GuidelinesforEvaluatingandExp... Open at page → 44 Page 44 FIBEROPTICPOWERMETER Model ,SerialNo. withGeDetector,SerialNo. Becausethemonochromator-based measurementresultsinTableIwereshiftedtomatchthelaser-based measurementresults,thereisanassociateduncertaintyaddedtotheoveralles... Open at page → 45 Page 45 FIBEROPTICPOWERMETER Model ,SerialNo. withGeDetector,SerialNo. FortheDirector, NationalInstituteofStandards andTechnology ReportReviewedBy: GordonW.Day,DivisionChief OptoelectronicsDivision ChristopherL.Cromer,ProjectLea... Open at page → 47 Page 47 TechnicalPublications Periodical JournalofResearchoftheNationalInstituteofStandardsandTechnology—ReportsNISTresearch anddevelopment inthosedisciplinesofthephysicalandengineeringsciencesinwhichtheInstitute is active.These... 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