光纤通信技术（英文版）

Fiber-OpticCommunicationTechnology2023/12/12Outline1.Introduction2.Fiber

→

(Loss,Dispersion,Nonlinearity)3.OpticalTransmitter→(LD/LED,Drivingcircuit)4.OpticalReceiver→(PIN/APD,Noise,Sensitivity)5.System→(Structure&Design)6.Frontiers→(EDFA,DWDM,OTDM,AON)Fiber-OpticCommunicationTechnologyChapter1Introduction2023/12/14Chapter1.IntroductionSystemComponents&CharacteristicsEvolutionReviewBasicConcepts2023/12/15Nearinfrared近红外DWDM:densewavelengthdivisionmultiplexing密集波分复用Modulationformat调制格式Regenerator再生器Repeaterspacing中继距离Bitrate-distanceproduct比特距离的乘积Dispersionshiftedfiber色散位移光纤Submarinetransmissionsystem海底传输系统Dryfiber无水光纤Opticalsoliton光孤子Binaryrepresentation二进制表示方法Samplingtheorem抽样定理Nyquistcriterion奈奎斯特准则Quantizationnoise量化噪声PPM：脉冲位置调制PDM：脉冲宽度调制PCM：脉冲编码调制TDM：时分复用FDM：频分复用Digitalhierarchy数字体系SONET：同步光网络SDH：同步数字体系STM：同步转移模块RZ:归零码NRZ：非归零码CSRZ：载波抑制归零码AM，FM，PM：幅度/频率/相位调制ASK/FSK/PSK幅/频/相移键控OOK：通断键控Free－spacecommunication自由空间光通信系统Opticaltransmitter光发射机Launchedpower发射功率IM/DD:强度调制/直接探测BER：误码率Receiversensitivity接收机灵敏度Quantumnoise量子噪声Shotnoise散粒噪声Thermalnoise热噪声2023/12/161.1SystemComponents&Characteristics1.1.1ComponentsinLightwaveSystems

Carrier→OpticalwaveMedium→Opticalfiber2023/12/17Fig.1.1Schemeofopticalfibercommunicationsystems2023/12/18CATV2023/12/19OpticalTransmitterBinarytosingleCoding/linecodingModulatorOpticalSourceDrivingCircuitPCMChannelcouplerOpticalsignaloutputLDorLEDLaunchingpower,spectrallinewidth!2023/12/110LaserDiode2.5Gb/stransmitter

MQW-DFB-LD2023/12/111OpticalFiber

FiberLossFiberDispersionFiberNonlinearity&High-orderDispersion2023/12/112RepeaterRepeater3R:ReamplificationRetimingReshaping1.O/E/O3R2.O/O2R:opticalamplifier,dispersioncompensation2023/12/113OpticalamplifierEDFASOA2023/12/114DispersionCompensationbyUsingChirpedBraggGrating

Chirped

Bragggrating••

•

llonglshortG.652:PositiveDispersion@1550nmChirpedBraggGrating2023/12/115OpticalReceiverChannelcouplerPhotondetectorPreamplifierLinearchannelDecisionSingle-binaryDecodingPCMsignalOpticalsignalinputNosie&sensitivity!PINorAPD2023/12/116Photondetector2.5Gb/sAPD

10Gb/sPIN2023/12/117Simulation

2023/12/1181.1.2CharacteristicsAdvantagesOpticalwave→Carrier→B,

ForDWDMapplicationin1.55μmwindow

morethanmicrowave2023/12/119Opticalfiber(lowloss)→Media→Repeaterspacing Capacity→B*L(Bitratedistanceproduct)

:bit/s·km

Ex.:telegraph→telephone→coaxialcable→microwave →opticalwave→EDFA→DWDMSignalwellprotected&ImmunetoelectricalinterferenceEconomical(silica)Noteasytobecorroded

2023/12/120Really？！2023/12/121DisadvantagesDifficulttocoupleandsplitDifficulttoconnect:fusedsplicingUnabletobendsharplyEasytobebroken2023/12/122LensedFiber&Collimator2023/12/123Chapter1.IntroductionSystemComponents&CharacteristicsEvolutionReviewBasicConcepts2023/12/1241.2EvolutionReview1.2.1EarlytimeFire，smokesignalsOpticaltelephone(Bell,1880)Fig.1.2Opticaltelephone2023/12/125opticalsource:notstable,reliable media:largeloss1960,Maiman

Rubylaser:stable,reliableopticalsource

atmosphere:largescatteringloss

2023/12/1261.2.2MilestoneinEvolutionFiber:lowlossmedia!1966,K.C.Kao1000dB/kmto20dB/km(byreducingconcentrationofimpurities)

1970,Corning→20dB/km

1972,Corning→7dB/km 1973,Belllab→2.5dB/km 1976,Japan→0.5dB/km@1.55µm

1979,→0.2dB/km@1.55µm

now

→0.16dB/km@1.55µm

Limitation:Rayleighscattering&intrinsicabsorption2023/12/127LD:stable,reliableopticalsource!

1970,DFB(distributedfeedback)theory 1975,Longwavelengthlaserdiode

InGaAsP/InP,λ>1µm

µm=10-6m,nm=10-9m,pm=10-12m 1985,Multi-quantumwell→MQW-DFBLD lowthreshold→10mA narrowbandwith→0.1nm@-20dB highoutputpower→1mw

2023/12/128Systems:

1976,Atlanta,lightwavesystem

1977,Chicago,fieldtest:audio,data,video

2023/12/1291.2.3SeveralGenerations

Thefirstgeneration

LD→multi-longitudinalmode(MLM)

Fiber→multimodefiber

λ→0.85µm(3.5dB/km)

ThesecondgenerationLD→MLMFiber→multimodefiber→singlemodefiber

λ

→1.31µm(loss,dispersion)2023/12/130ThethirdgenerationLD→MLM→singlelongitudinalmode(SLM)Fiber→singlemodefiber→dispersion-shiftedfiber

λ→1.55µm(loss,dispersion)

ThefourthgenerationWDM+EDFADispersionmanagement!2023/12/131

Thefifthgeneration

soliton+dispersionmanagement2023/12/132FunctionalityYear199420002006OpticalNetworkEvolution

opticalamplifierspoint-to-pointWDM&DWDMDWDMpoint-to-multipointStaticOADMsdynamicOADMs

e-g-STM1ondemandColouredsectionringsOXCandDXCco-existencewavelengthconversionWavelengthroutingOpticalpacketswitchingConnectivityCapacityFlexibility2023/12/133Chapter1.IntroductionSystemComponents&CharacteristicsEvolutionReviewBasicConcepts2023/12/1341.3BasicConcepts 1.3.1Analog&DigitalSignals Fig.1.3Representationof(a)ananalogsignaland(b)adigitalsignalAnalogsignals:audio,video(continuous)Digitalsignals:data(discrete,binaryrepresentation)

2023/12/135Fig.1.4.Threestepsofrequiredforconvertingananalogsignalintoabinarydigitalsignal(a)sampling,(b)quantization,and(c)coding.

2023/12/136Analog→DigitalSampling:fs2⊿f(NyquistCriterion)Quantization:leadingadditionalnoise!M>Amax/AN

Amax:themaximumamplitudeofthegivensignal AN:theroot-mean-squareamplitudeoftheanalogsignalSNR(signal-to-noiseratio)=20log10(Amax/AN)Coding:mlog2M

m:numberofbits,M:quantizedsignallevel2023/12/137⊿f→B?B=mfs=log2M·2⊿f SNR=20log10(Amax/AN) M>Amax/AN

B>(⊿f/3)·SNREx.HDTV:SNR=50dB,⊿f=4MHz,B>66Mbit/s Whyusedigitalsignalsforopticaltransmission?2023/12/138Analog:AM,FMandPMAM1.3.2ModulationFormats2023/12/139Digital:ASK,FSK,PSKFSKPSKforopticalcarrier

?UsuallyOOK(on-offkeying)---intensitymodulation!2023/12/140RZ&NRZ

clockforretiming,butlargebandwidth!

smallbandwidth,butbit-pattern-dependenteffectFig.1.5Digitalbitstream010110…codedbyusing(a)return-to-zero(RZ)and(b)non-return-to-zero(NRZ)formats.2023/12/1411.3.3ChannelmultiplexingTDM

Channel210101Channel1

110011001110101

t

1FDM10101Channel1Channel2101011010110101

1

2

t

1

2TDM&FDM2023/12/142ETDMFordigitalvoicechannel,sampling24channels,samplinggatecouldbeopenfor125/24microsecond.Bitrate:64k*24=1.536Mb/s12422023/12/14364