- th International Conference - Tunable Diode Laser 第八届国际会议可调谐二极管激光器

PAGE

PAGE

147

Organizedby:

ConnecticutCollege,NewLondon,ConnecticutUSA

GeneralPhysicsInstitute,RussianAcademyofSciences,Moscow,Russia

SupportedandSponsoredby:

CanberraAquila,Inc.

EKIPSTechnologies

LaserComponentsGroup

SacherLasertechnikGroup

AerodyneResearch,Inc

TopticaPhotonics

NanoplusNanosytems

AeroLaser

AlpesLasersSA

MesserGriesheimGmbH

ConferenceChairs

A.W.Mantz A.I.Nadezhdinskii

ConnecticutCollege GeneralPhysicsInstitute

DepartmentofPhysicsAndAstronomy RussianAcademyofSciences

270MoheganAvenue 38VavilovStreet

NewLondon,Connecticut06320-4196USA Moscow117942Russia

Phone:1(860)439-5030Fax:1(860)439-5011 Phone:7(095)135-8281Fax:7(095)135-8281

E-Mail:

awman@

E-Mail:nad@nsc.gpi.ru

LocalOrganizers

GisbertWinnewisser UniversityofCologneandKOSMAOnTheGornergrat

ErwinFlueckiger HochalpineForschungsstationen

InternationalAdvisoryCommittee

ClaudeAlibert(France)

GhislainBlanquet(Belgium)

PaulDavies(UnitedKingdom)

AlanFried(USA)

ArminLambrecht(Germany)

MaximSpiridonov(Russia)

ClaudeThiebeaux(France)

HiromichiUehara(Japan)

AlainValentin(France)

PeterWerle(Italy)

GisbertWinnewisser(Germany)

ConferenceWebPage:

E-mail:

tdls@

TDLS2003ConferenceSchedule

SundayJuly132003

16:00-18:00 Registration

MondayJuly142003

8:30-Noon Registration

8:45-12:30 PlenarySession

8:45-9:00 Opening

SessionChair: ClaudeThibeaux

9:00-9:45 InvitedLecture1-A.R.W.McKellar

9:45-10:30 InvitedLecture2-NobukimiOhashi

10:30-11:00 CoffeeBreak

SessionChair: FrankTittel

11:00-11:45 InvitedLecture3-RuedegerKoehler

11:45-12:30 InvitedLecture4-MurielLepere

Lunch

14:00-16:00 PosterSessionA

16:00-16:30 Break

SessionChair: ArminLambrecht

16:30-17:15 InvitedLecture5-StephaneSchilt

17:15-18:00 InvitedLecture6-DanielHofstetter

18:00-19:00 WelcomeReception

TuesdayJuly152003

SessionChair: PeterWerle

9:00-10:30 SpecialIndustrialPlenarySessionI

10:30-11:00 CoffeeBreak

11:00-12:30 SpecialIndustrialPlenarySessionII

Lunch

SessionChair: PeterWerle

14:00-15:00 SpecialIndustrialPlenarySessionIII

SessionChair: AlanFried

15:00-17:00 PosterSessionB

17:00-17:45 InvitedLecture7-YuriPonomarev

17:45-18:30 InvitedLecture8-MatthewTaubman

WednesdayJuly162003

9:00-12:30 PlenarySession

SessionChair: A.R.W.McKellar

9:00-9:45 InvitedLecture9-GeorgesDurry

9:45-10:30 InvitedLecture10-MarkZahniser

10:30-11:00 CoffeeBreak

SessionChair: YuriPonomarev

11:00-11:45 InvitedLecture11-JürgenRöpcke

11:45-12:30 InvitedLecture12-DanielHurtmans

Lunch

SessionChair: KoichiUehara

14:00-14:45 InvitedLecture13-MartinFejer

14:45-15:15 Break

15:15-17:30 PosterSessionC

19:00 Banquet

ThursdayJuly172003

9:00-12:30 PlenarySession

SessionChair: MurielLepere

9:00-9:45 InvitedLecture14–BrunoGayral

9:45-10:30 InvitedLecture15-BertrandParvitte

10:30-11:00 CoffeeBreak

SessionChair: MarkZahniser

11:00-11:45 InvitedLecture16-DirkRichter

11:45-12:30 InvitedLecture17-KayNiemax

Lunch

14:00-16:00 PosterSessionD

SessionChair: DanielHurtmans

16:00-16:45 InvitedLecture18-DanieleRomanini

FridayJuly182003

8:30-10:00 PosterSessionE

10:00-10:30 CoffeeBreak

SessionChair: GisbertWinnewisser

10:30-11:15 InvitedLecture19-DougBaer

11:15-12:30 InvitedLecture20-FrankTittel

12:30 ClosingRemarks

Contents:

HYPERLINK

Part1.InvitedLecture

………………….…………..7

HYPERLINK

Part2.IndustrialSession

………….29

HYPERLINK

Part3.PosterPresentation

……..….48

HYPERLINK

3.1.PosterSessionA

……….48

HYPERLINK

3.2.PosterSessionB

……………….………68

HYPERLINK

3.3.PosterSessionC

…………………...…..88

HYPERLINK

3.4.PosterSessionD

………………..…….107

HYPERLINK

3.5.PosterSessionE

……127

HYPERLINK

Part4.AuthorIndex

…………….……………….147

Part1.InvitedLecture.

HYPERLINK

Lecture1.TDLSpectroscopyofSmallHeliumClusters

A.R.W.McKellar

HYPERLINK

Lecture2.NEAR-INFRAREDDIODELASERSPECTROSCOPY

ONFREERADICALS

NobukimiOhashi

HYPERLINK

Lecture3.TERAHERTZQUANTUMCASCADELASERS

RüdegerKöhler,AlessandroTredicucci,FabioBeltram,HarveyE.Beere,

EdmundH.Linfield,A.GilesDavies,DavidA.Ritchie

HYPERLINK

Lecture4.LINEPROFILESTUDYWITHTUNABLEDIODE-LASER

SPECTROMETERS

M.Lepère

HYPERLINK

Lecture5.PHOTOACOUSTICSPECTROSCOPYININDUSTRIALAPPLICATIONS

S.Schilt,L.Thévenaz,P.Robert

HYPERLINK

Lecture6.LATESTPROGRESSONINTERSUBBANDDEVICES:

LASERSANDDETECTORSFROMTHENEAR-TOTHEFAR-INFRARED

DanielHofstetter,MarcelGraf,GiacomoScalari,LassaadAjili,

MattiasBeck,DavidRitchie,EdmundLinfield,HarveyBeere,

HongWu,WilliamJ.Schaff,LesterF.Eastman,JérômeFaist

HYPERLINK

Lecture7.Photo-acousticMeasurementsofGasand

AerosolAbsorptionwithDiodeLasers

Yu.N.Ponomarev

HYPERLINK

Lecture8.QUANTUMCASCADELASERS:STABILIZATION,

INJECTIONANDCONTROL.

MatthewTaubman,TanyaMyers,BretCannon,RichardM.Williams.

HYPERLINK

Lecture9.IN-SITUSENSINGOFTHEMIDDLEATMOSPHEREWITH

BALLOONBORNENEAR-INFRAREDDIODELASERS

G.Durry

HYPERLINK

Lecture10.TraceGasMeasurementsUsingPulsedQuantum

CascadeLasers-AtmosphericandEnvironmental

MonitoringApplications

MarkS.Zahniser

HYPERLINK

Lecture11.RECENTPROGRESSINDIAGNOSTICSOFMOLECULAR

PLASMASUSINGINFRAREDDIODELASERS

JürgenRöpcke

HYPERLINK

Lecture12.MOLECULARLINESHAPEANALYSISOFTDL

SPECTRABYMULTISPECTRUMFITSACCOUNTING

FORFINECOLLISIONALEFFECTS

DanielHurtmans

HYPERLINK

Lecture13.MID-INFRAREDCOHERENTSOURCESBASED

ONMICROSTRUCTUREDNONLINEARMATERIALS

MartinFejer

HYPERLINK

Lecture14.ApplicationofTLDAStogasmixtureanalysis–

Applicationtothemethane/ethanesystem

BrunoGayralandStéphaneVannuffelen

HYPERLINK

Lecture15.MID-INFRAREDHETERODYNEDETECTIONWITH

TUNABLELASERS

B.Parvitte

HYPERLINK

Lecture16.ANALYTICALPHOTONICSFORHIGHPRECISION

MIDINFRAREDTRACEGASSENSING

DirkRichter,AlanFried,andJamesG.Walega

HYPERLINK

Lecture17.ELEMENTSELECTIVEDETECTIONOFMOLECULAR

SPECIESUSINGCHROMATOGRAPHICTECHNIQUESAND

DIODELASERATOMICABSORPTIONSPECTROMETRY

KayNiemax

HYPERLINK

Lecture18.CavityRingDownandCavityEnhanced

Absorptionspectroscopy,andtracedetection,

withdiodelasers

DanieleRomanini

HYPERLINK

Lecture19.BeyondCavityRingDown:CavityEnhanced

SpectroscopyTechniquesUsingTunableDiodeLasers

DougBaer,ManishGupta,TomOwano,AnthonyO’Keefe

HYPERLINK

Lecture20.CHEMICALSENSINGWITHQUANTUMCASCADELASERS

F.K.Tittel,A.A.Kosterev,Y.Bakhirkin,C.Roller,

D.WeidmannandR.F.Curl

Lecture1.

TDLSpectroscopyofSmallHeliumClusters

A.R.W.McKellar

SteacieInstituteforMolecularSciences

NationalResearchCouncilofCanada

Ottawa,ONK1A0R6

Canada

Weaklyboundmolecularcomplexesandclustersareinvestigatedusingatunableinfrareddiodelaserspectrometertoprobeapulsedsupersonicjetexpansion.Thelaseroperatesinarapidscanmode,repeatedlytuningoverafixedinterval(0.3~1.0cm-1)inatimeof1msecwhilethepulsedjetnozzleisalternatelyopen(forthesignal)orshut(forthebackground).Theresultingspectrum(signalminusbackground)istypicallyaveragedfor100to500pulsesatarepetitionrateof1to5Hz.Thejetnozzlemaybeslitshaped,givingnarrowerlinewidths,orpinholeshaped,givingbroaderlinesbutlowerrotationaltemperaturesandmoreclustering.Thelaserbeamispassedthroughthejetmorethan100timesusingacommercialtoroidalmirrorsystemmountedinsidethevacuumchamber.ThechamberisevacuatedwithaVarianVHS-10diffusionpumpbackedbyanEdwardsEH500/E2M40booster/mechanicalpumpcombination.

Byusingmoderatelyhighbackingpressures(<40atmospheres)andcoolingthejetnozzle(>125K),wehavebeenabletoobservehighresolutionspectraofclusterscontainingupto20Heatomsandasingleinfraredchromophoremolecule,OCS,N2O,CO2,orCO.TheseareprobablythelargestvanderWaalsclusterswhichhavesofarbeenstudiedbyhighresolutionspectroscopy.

InthecaseofOCS,therotationalassignmentsforclustersuptoHe8-OCSareconfirmedbymicrowaveobservationsoftheanalogouspurerotationaltransitions[seeScience297,2030(2002)].Theresultsexploretheformationofthefirstsolvationlayer,beginningwithanequatorial‘donut’offiveHeatomsaroundtheOCSmolecule,andtheyarerelevantforstudiesoftheonsetofsuperfluideffectsinfinitesizesystems.InthecaseofHeN-COclusters,twoseriesofR(0)transitionsareobserved,eachcorrelatingsmoothlywiththeknowna-type(K=00)andb-type(K=10)R(0)linesofthebinarycomplex,He-CO.Althoughtheb-typeseriesstartsoffabout7timesstrongerforN=1,itisobservedtoloseintensitytotheaserieswithincreasingN.ThenumberingofclustersizeisreliablyestablisheduptoN=14forthea-typeandN=6fortheb-typeseries.Twocriticalregionsareobservedintheclustersizeevolution,ataboutN=7and15.Thesemayberelatedtothetheoreticallycalculatedmaximumandminimum,respectively,intheincrementalbindingenergyperheliumatom.

Lecture2.

NEAR-INFRAREDDIODELASERSPECTROSCOPYONFREERADICALS

NobukimiOhashi

DepartmentofPhysics,FacultyofScience,KanazawaUniversity,

Kakuma,Kanazawa920-1192,Japan

Thenear-infrareddiodelaserspectroscopyisoneofpowerfultoolsforstudyingspectrafrommolecularfreeradicals.Thehigh-sensitivity,highresolutionandtunabilityofthenear-infrareddiodelasersystemareofgreatadvantagetoinvestigationonenergylevelsofshort-livedradicalswhicharecomplicatedbecauseofvariousintra-molecularinteractions.Inourlaboratory,using0.8m,1.3mand1.5mtunablediodelasers,absorptionspectraofseveralradicalshavebeenstudiedintheirelectronictransitions.

ResultsonHCSi,CCO(1)andFeC(2)obtainedbystudyingindetailenergylevelstructureswiththeuseof0.8-mdiodelasersystemwillbereportedmainlyinthepresenttime.Oftheseradicals,CCOwasinvestigatedmainlywiththeuseofseveralsetsoflaserdiodesoscillatingwithinconvenientmodegapsintheearlystageofournear-infrareddiodelaserspectroscopicstudyonradicals,and,ontheotherhand,FeCandHCSiwerestudiedusinganexternalcavitydiodelaser.

ForFeC,beinganinterestingradicalcomposedofa3dtransitionmetalatomFe,informationonspin-orbitinteractionbetweenthetripletelectronicgroundstateandalow-lyingsingletelectronicexcitedstatewillbereportedsomewhatindetail.ForHCSiandCCOradicals,spectralvarietiesproducedbyRenner-Tellerinteraction,whichisaninterestingvibronicinteraction,willbementionedinaviewpointofhigh-resolutionspectroscopicinterest.ItcanbesaidthatdetailsofspectralcomplicationofthesetworadicalscausedbycombinationofRenner-Tellereffectandaspin-orbitinteractionweremadesuccessfullyclearofbyusingdiodelaserswhichoscillatestablyandareofhighqualityintunabilityandresolution.Examplesofsolvingthespectralcomplicationswillbeshown.

(1)M.Fujitake,R.Kiryu,andN.Ohashi,J.Mol.Spectrosc.154,169(1992).

N.Ohashi,R.Kiryu,S.Okino,andM.Fujitake,J.Mol.Spectrosc.157,50(1993).

H.Abe,T.Kikuchi,K.Takahashi.M.Fujitake,andN.Ohashi,J.Mol.Spectrosc.167,353(1994).

H.Abe,T.Kawamoto,M.Fujitake,N.Ohashi,T.Momose,T.Shida,,J.Mol.Spectrosc.180,277(1996).

H.Abe,M.Mukai,M.Fujitake,andN.Ohashi,J.Mol.Spectrosc.195,317(1999).

(2)M.Fujitake,A.Toba,M.Mori,F.Miyazawa,N.Ohashi,K.Aiuchi,andK.Shibuya,J.Mol.Spectrosc.

208253(2001).

Lecture3.

TERAHERTZQUANTUMCASCADELASERS

RüdegerKöhler,1)AlessandroTredicucci,1)FabioBeltram1)

HarveyE.Beere,2)EdmundH.Linfield,2)A.GilesDavies,2)DavidA.Ritchie2)

1)NEST-INFMandScuolaNormaleSuperiore,PiazzadeiCavalieri7,56126Pisa,Italy

2)CavendishLaboratory,UniversityofCambridge,MadingleyRoadCB30HE,Cambridge,UnitedKingdom

Theuseofterahertzradiation(1-10THz)hasproventobeaversatiletoolinspectroscopyandsensing[1],inmedicalimagingandindustrialprocesscontrol,andinsecurityscreening.Yet,theexploitationandexplorationofthesefieldshasbeenhamperedbythelackofappropriate,convenientsources.Commonsourcessuchasblackbodyradiation,free-electronlasers,opticallypumpedgaslasers,thep-Gesemiconductorlaser,photo-mixers,andAustonswitchessufferfromdifferentshortcomingsthatpreventtheiruseinreal-wordapplications[2].

Thequantumcascadelaserdemonstratedin1994byJ.Faistetal.[3]atmid-infraredwavelengthshasexperiencedarapiddevelopmentofitsperformanceandeventuallycw-operationatroom-temperaturewasdemonstrated.SinceitisbasedonintersubbandratherthaninterbandtransitionsthewavelengthcanbetunedoververywiderangesbyproperlyadjustinglayerthicknessandelectricfieldusingtechnologicallymaturematerialslikeInGaAs/AlInAs/InPorAlGaAs/GaAs.WehavedemonstratedAlGaAs/GaAsquantumcascadelasers[4]thatemitat4.5THz,at3.5THz[5],andveryrecentlyat2.8THzandthathavethepotentialfordevice-likeimplementation.Theactiveregionconsistsofahundredrepetitionsofachirpedsuperlattice,speciallyengineeredtoachievepopulationinversionatenergiesbelowtheopticalphononresonance.Thiscoreisembeddedintoanoveltypeofpartiallymetallicwaveguidetoconfinetheverylongwavelengthradiationwithoutconcomitanthighopticallosses.Theconceptislooselybasedonthesurfaceplasmonconfigurationbutmakesuseofathin,highlydopedlayerwithappropriatedielectricconstantbetweenthelow-dopedactivecoreandthesemi-insulatingsubstratetoguideTHzradiationwithlowopticallossesof~5-10cm-1.Ourdevicescurrentlyoperateincontinuous-wavemodewithoutputpowersof4mWandupto45Kheatsinktemperature.Underpulsedexcitation,outputpowersof4.5mWatlowtemperaturesandstill1mWat65Karemeasured[6].

[1]D.Mittleman(Ed.),SensingwithTerahertzRadiation,Springer,Berlin,2003.

[2]R.E.Miles,P.HarrisonandD.Lippens(Eds.),TerahertzSourcesandSystems,NATOScienceSeriesIIVol.27,Kluwer,Dordrecht,2001.

[3]J.Faistetal.,QuantumCascadeLaser,Science264,553(1994).

[4]R.Köhleretal.,TerahertzSemiconductor-HeterostructureLaser,Nature417,156(2002).

[5]R.Köhleretal.,Low-thresholdquantumcascadelasersat3.5THz(=85µm),OpticsLetters,inpress(2003).

[6]R.Köhleretal.,High-performancecontinuous-waveoperationofsuperlatticeterahertzquantum-cascadelasers,Appl.Phys.Lett.82,1518(2003).

Lecture4.

LINEPROFILESTUDYWITHTUNABLEDIODE-LASERSPECTROMETERS

M.Lepère

PostdoctoralResearcherwithF.N.R.S.,Belgium

LaboratoiredeSpectroscopieMoléculaire,FUNDP,

61,ruedeBruxelles,B-5000Namur,Belgium

Diode-laserspectrometersarewelladaptedtothestudyoflineshapesformoleculesindilutedphase.Theypermittoshowthemodificationsinducedbyintermolecularforcesonspectrallineprofileandgiveverypreciselineparametersforlineshapemodelisation.

Thedifferentlineprofilemodelstakeintoaccountseveraleffects.ThefirsteffectresultsfromrandommotionoftheactivemoleculeswhichleadstoabroadeningofthelinedescribedbyaDopplerprofilewhenthesampleisatthermalequilibrium.Thisisvalidonlyiftherearenosignificantinteractionsbetweenmolecules(verylowpressure).Atpressuresbelow120mbar,theDopplerandcollisionalbroadeningsareconcurrentandtheprofileisusuallydescribedbyaVoigtprofile.However,theDopplerlineisnarrowedbytheconfinementoftheactivemoleculesinthebuffergas.ThiseffectisgenerallyreferredtoasDickenarrowing(orconfinementnarrowing),thenthelineprofileiswelldescribedbyeithertheRautianorGalatrymodels.Asthepressureincreases,thecollisionalbroadeningisprogressivelythemaineffectanddependsontherelativespeedofthecollisionpartnersforwhichitmaybenecessarytotakeintoaccountthedifferentclassesofspeedfromtheMaxwell-Boltzmanndistributionfortheabsorber.

Precisedeterminationsofspectroscopiclineparameterssuchascollisionalbroadeningandnarrowingareveryimportantforinfraredremotesensingoftheatmospheres.Thetemperaturedependenceoftheseparametersisalsorequiredforpreciseatmosphericsounding.Foratmospherictemperatures(200-300K),itisimportanttodeterminepreciselylinebroadeningsandtheirtemperaturedependence.Wewillshowexamplesofsuchstudies(CH4,CH3D…)thatwehaverealisedusinganabsorptioncelloperatingatselectedtemperatures(betweenroomtemperatureand77K)withatemperaturestabilizationbetterthan0.5K.

Preliminarycalculationsshowthattheintermolecularpotentialvariations,thathavenoimportanteffectatroomtemperature,canproducedifferencesofseveralorderofmagnitudeatverylowtemperature(below20K).Thus,itseemsveryinterestingtomakemeasurementsuptothesetemperaturesusingcollisionalcoolingtechnique.Thistechniqueallowstoobtainagasmixtureinthermodynamicequilibrium,andthustoknowthepressureandthetemperatureofthegassample.Itisanadvantageforthestudyoflineprofileandparameters.IncollaborationwithProfessorMantz,wehaverealizedfirstmeasurementsofcollisionalbroadeningsofCH4dilutedinHedownto15K.

Lecture5.

PHOTOACOUSTICSPECTROSCOPYININDUSTRIALAPPLICATIONS

S.Schilt,L.Thévenaz,P.Robert

LaboratoryofMetrologyandPhotonics

SwissFederalInstituteofTechnology(EPFL),CH-1015Lausanne,Switzerland

(e-mail:stephane.schilt@epfl.ch)

M.Niklès

OmnisensSA

ParcScientifiqued’Ecublens,CH-1015Lausanne,Switzerland

Photoacousticspectroscopyisanextremelysensitivetechniquefortracegasmonitoring.Inthismethod,themoleculesofthespeciestobeanalyzedareselectivelyexcitedbyamodulatedlaserbeamofappropriatewavelength.Thesubsequentnon-radiativerelaxationoftheexcitedmoleculesproducesaperiodicheatingofthesampleandhence,apressuremodulation.Ifthelaserbeamismodulatedintheaudiofrequencyrange,anacousticwaveisthusgeneratedatthesamefrequency.Theamplitudeofthissoundwaveisdirectlyproportionaltotheamountoflightabsorbedinthesample(thustothegasconcentration)andcanbeeasilydetectedusingasimpleandverysensitivemicrophone.Inoppositetoothertraditionalspectroscopicmethods,inwhichthelighttransmittedthroughthesampleismeasured,photoacousticspectroscopyallowsthedirectdeterminationofthelightabsorbedinthesample.Therefore,itpresentstheadvantagetobeazero-backgroundtechnique,i.e.nosignalisproducedwhennoabsorbingsubstanceispresent.

Thesensitivityofthetechniquecanbestronglyimprovedusingaresonantconfiguration,inwhichthemeasurementcelliscarefullydesignedtobeanacousticresonator.Whenthelasermodulationcorrespondstoanacousticresonanceofthecavity,anacousticstandingwaveisbuiltintheresonator.Thisstandingwavecanaccumulateenergytoanextendmuchlargerthantheenergyinputpercycle,leadingtoanincreaseofthewaveamplitudeincomparisontothenon-resonantcase.TheacousticsignalisthusenhancedbythequalityfactorQoftheresonance,whichcanreachseveralhundredsforwell-designedphotoacousticcells.

Thebasicprinciplesofresonantphotoacousticspectroscopywillbedescribedandthedifferenttypesofresonances(longitudinal,radial,azimuthal)willbediscussed.Then,anoptimaldesignofaphotoacousticcellcoupledtoaCO2-laserwillbepresented.ThissystemhasleadtotherealizationofacommercialinstrumentforextremelylowNH3-concentrationsmeasurement.Applicationsofthisinstrumenttothecontroloftheatmosphereincleanroomsinthesemiconductorindustryandtoenvironmentalmonitoringwillbedemonstrated.Differentexperimentalresultsobtainedintheseapplicationsandshowingasub-ppbdetectionlimitwillbepresented.

Finally,applicationsofphotoacousticspectroscopyusingnear-infraredsemiconductorlaserdiodeswillbepresented.Differentcellconfigurationswillbediscussedasafunctionofthelaserspecifications.

Lecture6.

Latestprogressonintersubbanddevices:lasersanddetectorsfromthenear-tothefar-infrared

DanielHofstettera),MarcelGrafa),GiacomoScalaria),LassaadAjilia),MattiasBecka),DavidRitchieb),EdmundLinfieldb),HarveyBeereb),HongWuc),WilliamJ.Schaffc),LesterF.Eastmanc),andJérômeFaista)

a)UniversityofNeuchâtel,InstituteofPhysics,CH–2000Neuchâtel

b)CavendishLaboratory,UniversityofCambridge,Cambridge,UK

c)CornellUniversity,Ithaca,NY,USA

4thInternationalConferenceonTunableDiodeLaserSpectroscopy

Zermatt,Switzerland,July14-18,2003

Duringthelasttenyears,opto-electronicdevicesbasedonintersubbandtransitionshaveseenadevelopmentataveryfastpace.Asanexample,quantumcascadelasershavebecomereliablesourcesforthevariousapplicationsinthemid-infrared,andmostrecentlyalsointhefar-infrared.Likewise,quantumwellinfraredphotodetectorsarenowimportantbuildingblocksofthermalimagingsystemsinthemid-infrared.Inthefirsthalfofthispresentation,wereportonroomtemperaturecontinuouswaveoperationofanInP-based9.1

µmquantumcascadelaser,aswellasona77

Koperatedcontinuouswavefar-infraredquantumcascadelaserbuiltfromGaAs/AlGaAs.Thesecondpartwillbedevotedtophotodetectors.Werecentlydemonstratedsuchdevicesinthefar-infraredandinthenear-infraredwavelengthregion.WhiletheformerdeviceiscontainsachirpedAlGaAs/GaAs-superlattice,thelatterisbasedonaregularGaN/AlNsuperlatticewithaperiodof40

Å.

Lecture7.

Photo-acousticMeasurementsofGasandAerosolAbsorptionwithDiodeLasers

Yu.N.Ponomarev

InstituteofAtmosphericOpticsSBRAS

Akademicheskiiave.1,Tomsk634055,Russia

E-mail:yupon@iao.ru

Lasersensorsandgasanalyzersarenowatthebeginningofcommercialapplicationsinenvironmentalmonitoringofgreenhousegasesandindustrialpollutants.

TDLStechniquesareavailableformeasurementsofnanoconcentrationsofmoleculesingaseswithinIRspectralrange.ThemostpopulartypesofTDLinstrumentsforspectroscopyorgasanalysisarebasedontheusageofthedifferentmultipassabsorptioncells.Thetechniquesprovidethemeasurementsofsmallvaluesoftheabsorbingmediaopticaldepthupto10-6.Thatcorrespondsthelimitconcentrationsensitivityatppt–ppmlevel,dependingonthevalueoftheabsorptioncrosssectionofthedetectedmolecules.InanotherversionofTDLspectrometersandgasanalyzersthesensitivephoto-acousticdetectors(PAD)ofnonresonantor,previously,resonanttypeareused.Theadvantagesofthiskindoftechniqueare:

possibilitytorecordPAspectraagainstzerobackground;

lineardependenceofthePADsignalamplitudeontheconcentrationofthedetectedmolecules;

linearityofthePADatvariationoftheconcentrationofthedetectedgasupto6ordersofmagnitude;

usageofcheaptransparentopticalwindowsinsteadofhighreflectedmulti-layerdielectricmirrorswhicharenecessaryformultipasscells.

InthepaperthereviewofresultsofIAOSBRASwithcollaboratorsonthecreationandapplicationofdifferenttypesofPADtohighresolutionandhighsensitivespectroscopyofmoleculargasesandanalysisofmulti-componentgasmixturesispresented.

TheadvantagesofresonantPADdetectorsforspectroscopyandgasanalysisofgasflows,vibrationkineticsofselectivelyexcitedmoleculesandhighsensitivemeasurementsofconcentrationsofmoleculesarediscussed.

Forthemeasurementsofthenon-resonantabsorptionofmoleculargasesanewtypeofPADwithatemporalandspatialresolutionwastested.Itprovidesthelimitabsorptionsensitivitybetterthan10-10cm-1J.TheapplicabilityofthisPADformeasuringnotonlynon-resonantabsorptionofgasesbutalsoweakabsorptionofsubmicronsizeaerosolparticlesisdiscussed.

TheresonantdifferentialPADprovidesthepossibilitiesofanewexperiments,likerecordingofspectraofhotabsorptionbandsofmoleculesexitedpreliminarybystrongselectiveradiationoftheIRlaserornonlinearabsorptionofgasesarediscussedinthepaper.

Lecture8.

QUANTUMCASCADELASERS:STABILIZATION,INJECTIONANDCONTROL.

MatthewTaubman,TanyaMyers,BretCannon

andRichardM.Williams.

PacificNorthwestNationalLaboratory,POBox999,MSK5-26,Richland,WA,USA.

QuantumCascadeLasers(QCLs)arearelativelynewtypeofsemiconductorlaseroperatinginthemid-tolong-waveinfrared.Beingmonopolarmultilayeredquantumwellstructures,theycanbefabricatedtooperateanywhereina3to20micronregion.Thismakesthemanidealchoiceforinfraredchemicalsensing,atopicofgreatinterestatpresent.Theirutilityisincreasedthroughstabilization,whichbothnarrowsthelinewidthandlockstheoutputfrequencytoaknownstandard,andthroughinjectionlocking,whichwehavedemonstratedtogreatlyreducetheamountofresidualamplitudemodulation(RAM)thatresultsfromcurrentmodulationofthedevices.Wepresentresultsofloc