光电子学 2007 chapter 11

《光电子学 2007 chapter 11》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Chapter11DetectionofopticalradiationIntroduction:thedetectionofopticalradiationisoftenaccomplishedbyconvertingtheradiantenergyintoanelectricsignalwhoseintensityismeasuredbyconventionaltechniques.Someofthephysicalmechanismsthatmaybeinvolvedinthisconversioninclude:Thegenerationofmobilec

2、hargecarriersinsolid---statephotoconductive(光电导的)detectors.Changingthroughabsorptionthetemperatureofthermocouples(热电偶),thuscausingachangeinthejunction(接头)voltage.Thereleasebythephotoelectriceffect(光电效应)offreeelectronsfromphotoemissive(发射的)surfaces.keywordsdynodescathodeanodephotomulti

3、plierphotoconductivedetectorphotodiodeavalanchephotodiodethermocouplesmobilityheterodynesensitivityconductionbandvalenceband(中间极)(阴极)(阳极)(光电倍增管)(光电导探测器)(光电二极管)(雪崩光电二极管)(热电偶)(迁移率)(外差法)(灵敏度).(导带)(价带))Inthischapterweconsiderinsomedetailtheoperationoffourofthemostimportantdetectors:Thepho

4、tomultiplier(光电倍增管)Thephotoconductivedetector(光电导探测器)Thephotodiode(光电二极管)Theavalanchephotodiode(雪崩光电二极管)bahvFigure11-1Mosthigh-speedopticaldetectorsdependonabsorptionofphotonsofenergyhvaccompaniedbyasimultaneoustransitionofanelectron(orhole)fromaquantumstateoflowmobility(迁移率)(a)tooneo

5、fhighermobility(b).Aphotonofenergyhvisabsorbedintheprocessofexcitinganelectronfroma“bound”stateatoa“free”statebinwhichtheelectroncancontributetothecurrentflow.11.1opticallyinducedtransitionratesThetransitionrateperelectronfromstateatobtotheintensityoftheopticalfieldcanbestatedinthefol

6、lowingform:Givenanearlysinusoidalopticalfield:ThetransitionrateisTakingE0andE1realand11.1-311.1-411.1-5Thisshowsthatthetransitionratehas,inadditiontoaconstantterm,acomponentoscillatingatthedifferencefrequencywithaphaseequaltothedifferenceofthetwooriginalphases.Thiscoherent“beating”eff

7、ectformsthebasisoftheheterodyne(外差法)detectionscheme.,whichisdiscussedindetailinsection11.4011.2photomultiplier(光电倍增管)Thephotomultiplier,oneofthemostcommonopticaldetectors,isusedtomeasureradiationinthenearultraviolet(紫外的),visible,andnearinfrared(红外)regionsofthespectrum.Becauseofitsinhe

8、renth