《光电类专业英语》课堂讲义文献

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1、光电类专业英语任基陈敏胡晓飞编著成都信息工程学院光电技术系二〇〇五年九月CONTENTTotal119UNIT111-1TheFunctionofLaser11-2OpticalFiberCommunications91-3OrganicLightEmittingDiodes151-4Holography251-5PhotoelectronSpectroscopy311-6PhotonicsUnlocksChipBandwidthBottleneck35UNIT2402-1HistoryofPhysics402-2StephenHawkingandBlackHoles4

2、52-3Electronics-AerospaceSynergy492-4Nanotechnology55UNIT3623-1ComputerSecurity623-2SupercomputersontheCheap663-3BluetoothTechnology703-4TeachingandLearningintheWirelessClassroom793-5WhatIstheFutureofTelecommunicationsNetworking843-6Introductionto3G94UNIT4984-1ThinkingBoldly,ActingWisely

3、984-2IncomeTax1044-3B2BE-commerce1094-4WTOBasicPrinciplesoftheTradingSystem115Unit11-1ThefunctionoflaserUnit11-1TheFunctionofLaserTheacronymLASERstandsforLightAmplificationbyStimulatedEmissionofRadiation.Alaserisadevicethatproducesabeamofmonochromaticlightinwhichallthewavesareinphaseorar

4、ecoherent.In1917,inthecourseofcalculationsontheequilibriumofagas,Einsteindiscoveredthattheremustbetwopossibletypesofemission.Atomstendtogravitatetowardtheirgroundstates.Sotheelectronsdropdownspontaneouslyandemitphotons.Thisprocessiscalledspontaneousemission.Einsteinwonderedwhatwouldhappe

5、nifanelectronwerealreadyinanexcitedstatewhenitencounteredaphotonoftheproperenergy.Anaturalconclusionwouldbethattheelectronwouldmovetostillhigherorbit.Natural,butwrong.Einsteinpredictedinsteadthattheelectronwoulddroptoalowerorbitandemitaphoton,asbyspontaneousemission,exceptthatinthiscaset

6、hestimulatingphotonwouldnotbeabsorbedbutwouldsimplycontinueonitsway.We’dthenendupwithtwophotonsofidenticalenergy,orwavelength.Einsteincalledthisstimulatedemission.-108-Unit11-1ThefunctionoflaserThisconcept,formulatedbyEinsteinin1916,wasthegermoftheideathateventuallyledtothelaser.Wehaveal

7、readyseenthatthewordlaserstandsforlightamplificationbystimulatedemissionofradiation.Asyoumayhavereasoned,ifyoucouldbombardatomswiththerightkindofphotonsandcatchenoughelectronsinexcitedstates,youwouldstimulatetheemissionofmorephotons,andyou’dbeonyourwaytomakinglaserlight—t