- th International Conference - Tunable Diode Laser 第八屆國際會(huì)議可調(diào)諧二極管激光器

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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-JürgenR?pcke

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

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Part2.IndustrialSession

………….29

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Part3.PosterPresentation

……..….48

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3.1.PosterSessionA

……….48

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3.2.PosterSessionB

……………….………68

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3.3.PosterSessionC

…………………...…..88

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3.4.PosterSessionD

………………..…….107

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3.5.PosterSessionE

……127

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Part4.AuthorIndex

…………….……………….147

Part1.InvitedLecture.

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Lecture1.TDLSpectroscopyofSmallHeliumClusters

A.R.W.McKellar

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Lecture2.NEAR-INFRAREDDIODELASERSPECTROSCOPY

ONFREERADICALS

NobukimiOhashi

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Lecture3.TERAHERTZQUANTUMCASCADELASERS

RüdegerK?hler,AlessandroTredicucci,FabioBeltram,HarveyE.Beere,

EdmundH.Linfield,A.GilesDavies,DavidA.Ritchie

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Lecture4.LINEPROFILESTUDYWITHTUNABLEDIODE-LASER

SPECTROMETERS

M.Lepère

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Lecture5.PHOTOACOUSTICSPECTROSCOPYININDUSTRIALAPPLICATIONS

S.Schilt,L.Thévenaz,P.Robert

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Lecture6.LATESTPROGRESSONINTERSUBBANDDEVICES:

LASERSANDDETECTORSFROMTHENEAR-TOTHEFAR-INFRARED

DanielHofstetter,MarcelGraf,GiacomoScalari,LassaadAjili,

MattiasBeck,DavidRitchie,EdmundLinfield,HarveyBeere,

HongWu,WilliamJ.Schaff,LesterF.Eastman,Jér?meFaist

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Lecture7.Photo-acousticMeasurementsofGasand

AerosolAbsorptionwithDiodeLasers

Yu.N.Ponomarev

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Lecture8.QUANTUMCASCADELASERS:STABILIZATION,

INJECTIONANDCONTROL.

MatthewTaubman,TanyaMyers,BretCannon,RichardM.Williams.

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Lecture9.IN-SITUSENSINGOFTHEMIDDLEATMOSPHEREWITH

BALLOONBORNENEAR-INFRAREDDIODELASERS

G.Durry

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Lecture10.TraceGasMeasurementsUsingPulsedQuantum

CascadeLasers-AtmosphericandEnvironmental

MonitoringApplications

MarkS.Zahniser

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Lecture11.RECENTPROGRESSINDIAGNOSTICSOFMOLECULAR

PLASMASUSINGINFRAREDDIODELASERS

JürgenR?pcke

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Lecture12.MOLECULARLINESHAPEANALYSISOFTDL

SPECTRABYMULTISPECTRUMFITSACCOUNTING

FORFINECOLLISIONALEFFECTS

DanielHurtmans

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Lecture13.MID-INFRAREDCOHERENTSOURCESBASED

ONMICROSTRUCTUREDNONLINEARMATERIALS

MartinFejer

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Lecture14.ApplicationofTLDAStogasmixtureanalysis–

Applicationtothemethane/ethanesystem

BrunoGayralandStéphaneVannuffelen

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Lecture15.MID-INFRAREDHETERODYNEDETECTIONWITH

TUNABLELASERS

B.Parvitte

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Lecture16.ANALYTICALPHOTONICSFORHIGHPRECISION

MIDINFRAREDTRACEGASSENSING

DirkRichter,AlanFried,andJamesG.Walega

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Lecture17.ELEMENTSELECTIVEDETECTIONOFMOLECULAR

SPECIESUSINGCHROMATOGRAPHICTECHNIQUESAND

DIODELASERATOMICABSORPTIONSPECTROMETRY

KayNiemax

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Lecture18.CavityRingDownandCavityEnhanced

Absorptionspectroscopy,andtracedetection,

withdiodelasers

DanieleRomanini

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Lecture19.BeyondCavityRingDown:CavityEnhanced

SpectroscopyTechniquesUsingTunableDiodeLasers

DougBaer,ManishGupta,TomOwano,AnthonyO’Keefe

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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

RüdegerK?hler,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.K?hleretal.,TerahertzSemiconductor-HeterostructureLaser,Nature417,156(2002).

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

[6]R.K?hleretal.,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),andJér?meFaista)

a)UniversityofNeuchatel,InstituteofPhysics,CH–2000Neuchatel

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

?.

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