《超短脉冲的产生》ppt课件

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1、Lecture3GenerationofultrashortpulsesTheMetricSystemPrefixes:Milli(m)10-3Micro(µ)10-6Nano(n)10-9Pico(p)10-12Femto(f)10-15Atto(a)10-18Kilo(k)10+3Mega(M)10+6Giga(G)10+9Tera(T)10+12Peta(P)10+15SmallBigWe’llneedtoreallyknowthemetricsystembecausethepulsesareincr

2、ediblyshortandthepowersandintensitiescanbeincrediblyhigh.The"TrottingHorse”ControversyPaloAlto,CA1872TheBirthofUltrafastTechnologyLelandStanford（马场老板）EadweardMuybridge(英国摄影师)TimeResolution:1/60thofasecondBet:Doallfourhoovesofatrottinghorseeversimultaneousl

3、yleavetheground?TrottingHorseHaroldEdgertonMIT,1942“HowtoMakeApplesauceatMIT”1964“SplashonaGlass”CurtisHurleyJuniorHighSchoolstudent1996TimeResolution:afewmicroseconds'Doc'Edgerton-StrobePhotography时间尺度电子运动时间尺度：阿秒（1as=10-18s)，电子绕氢原子核一周大约是150阿秒；原子转动时间尺度：皮秒（

4、1ps=10-12s）原子振动时间尺度：飞秒（1fs=10-15s)如监测化学反应过程，需飞秒尺度TheGenerationofUltrashortLaserPulsesTheimportanceofbandwidthMorethanjustalightbulbLasermodesandmode-lockingMakingshorterandshorterpulsesPulse-pumpingQ-switchinganddistributed-feedbacklasersPassivemode-lockin

5、gandthesaturableabsorberKerr-lensingandTi:SapphireActivemode-lockingOthermode-lockingtechniquesLimitingfactorsCommerciallasersButfirst:theprogresshasbeenamazing!YEARNd:glassS-PDyeDyeCWDyeNd:YAGDiodeNd:YLFCr:YAGCr:LiS(C)AFEr:fiberCr:forsteriteTi:sapphireCPM

6、w/CompressionColorCenter1965197019751980198519901995Dye2000SHORTESTPULSEDURATION10ps1ps100fs10fs2005Nd:fiberTheshortestpulsevs.year(fordifferentmedia)Continuousvs.ultrashortpulsesoflightAconstantandadelta-functionareaFourier-Transformpair.Continuousbeam:Ul

7、trashortpulse:Irradiancevs.timeSpectrumtimetimefrequencyfrequencyLongvs.shortpulsesoflightTheuncertaintyprinciplesaysthattheproductofthetemporalandspectralpulsewidthsisgreaterthan~1.LongpulseShortpulseIrradiancevs.timeSpectrumtimetimefrequencyfrequencyForm

8、anyyears,dyeshavebeenthebroadbandmediathathavegeneratedultrashortlaserpulses.Ultrafastsolid-statelasermediahaverecentlyreplaceddyesinmostlabs.Solid-statelasermediahavebroadbandwidthsandareconvenient.Laserpowe