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1、Fiber-OpticCommunicationTechnologyChapter4OpticalReceivers7/30/20211OE,HUSTChapter4OpticalreceiversBasicConceptCommonPhotodetectorsReceiverDesignReceiverNoiseReceiverSensitivitySensitivityDegradation7/30/20212OE,HUSTConfigurationRequirementshighsensit
2、ivityfastresponselownoiselowcost&highreliabilityopticalsignalvoltagesupplyO/Epre-amplifierautomaticgaincontrolamplifierfilterdecisioncircuitclockrecoveryPINorAPDdataFrontEndLinearChannelDataRecovery7/30/20213OE,HUSTSimulation7/30/20214OE,HUST4.1BasicC
3、oncepts4.1.1DetectorResponsivityStimulatedabsorption:photonanelectron-holepairPhotoncurrent:,R:responsivityQuantumefficiency:7/30/20215OE,HUST7/30/20216OE,HUST7/30/20217OE,HUST4.1.2RisetimeandBandwidthPinVout(t)90%10%V0TrτRC:timeconstantoftheRCcircuit
4、Forphotodiode:τtr:transittimeofcarriers,inputvoltage:0~V0outputvoltage:,Vd:driftvelocityRisetime0risetime:Tr7/30/20218OE,HUSTBandwidthofaphotodiodeDarkcurrentCausedbystraylightorthermallygeneratedelectron-holepairsTrade-offbetween7/30/20219OE,HUSTChap
5、ter4OpticalreceiversBasicConceptCommonPhotodetectorsReceiverDesignReceiverNoiseReceiverSensitivitySensitivityDegradation7/30/202110OE,HUST4.2Commonphotodetectors4.2.1p-nphotodiodesareversebiasedp-njunction7/30/202111OE,HUSTthepresenceofadiffusivecompo
6、nentdistortsthetemporalresponseofaphotodiode.solution:decreasingthewidthsofthep-andn-regions;increasingthedepletion-regionwidth.7/30/202112OE,HUST4.2.2p-i-nphotodiodes7/30/202113OE,HUSTi-layer→highresistance→largeelectricfield→thedepletionregionthroug
7、houtit→driftcomponentdominatesoverthediffusioncomponent→Double-heterostructuredesignp-InPn-InPInGaAsabsorptioncanonlyoccurinthemiddleofi-layerdiffusivecomponentiseliminatedcompletely7/30/202114OE,HUST7/30/202115OE,HUST4.2.3AvalanchePhotodiodesBasiccon
8、cepts7/30/202116OE,HUSTImpactionization:anacceleratingelectroncanacquiresufficientenergytogenerateanewelectron-holepair.aphotonasingleprimaryelectronmanysecondaryelectrons&holesi-layer:absorptionp-layer:multiplicationthroughimpactionizationimp