DWDM PrinciplesV1.1ContentWDM OverviewOptical Fiber Transmission characterKey technologies of DWDMTechnical SpecificationsSDM TDM WDM ac!gro"n#PDHSDHDWDM155M 622M 2.5G 10GG.957 G.691G.692PD$% SD$ an# DWDMIPIPATMATMSDHSDHDWDMPhysical i!erDWDMPhysical i!erO"e# O"$icalI#$er%aceO"e# O"$icalI#$er%aceSDHSDHATMATMIPIPO$herO$her&elationship bet'een DWDM an# Other Ser(icesWDM DefinitionWDM technology is a fiber comm"nication technology transmitting m"ltiple optical carriers 'ith information )analog or #igital* on one fiber.N21N21N21OM&OD&OAWDM Classification'WDM( ')arse Wavele#*$h Divisi)# M+l$i"le,i#*DWDM + De#se Wavele#*$h Divisi)# M+l$i"le,i#* DWDM ConceptDense 'a(elength #i(ision m"ltiple,ing )DWDM*P)wer )#m*1529 - 1561#./)nm*wavele#*$h i#$erval0.0 2#.OT-1I#"+$ Ch 1 Ch . Ch 1 Ch ./1/n OT-nOM-0 10 P0OD-/1/n OT-1OT-n/s /s/s/sOSCOSC OSCO+$"+$2MSO"$icalTra#s.i$$erO10O"$ical1eceiverDWDM systemCommon .2 in DWDM SystemClient sideLine side1 n 1 n OTMLine sideLine sideOLAClient sideLine sideLine side/1 /n /1 /nOADMTT&&l12lec$rical M+l$i"le, 2lec$rical De.+l$i"le,Tra#s.i$$er1eceiver2lec$rical 1e*e#era$)rl.l3l1l.l3l1l.l3l1O"$ical M+l$i"le,erO"$ical De.+l$i"le,erOATDM( 2lec$rical 1e*e#era$)r %)r Si#*le Wavele#*$hDWDM( M+l$i-wavele#*$h )# Si#*le i!er3 %)r O"$ical A."li%ica$i)#Difference bet'een DWDM an# SD$DWDM Feat"res1arge transparent transmission capacity greatly sa(es fiber reso"rces.2ach 'a(elength can carry #ifferent signal+ SD$ 3.45bps% 16 5bps% 0TM% 7P.DWDM technology pro(i#es m"ltiple (irt"al fiber channels in one physical fiber channel.DWDM Feat"resSDHThro"gh s"per8long #istance transmission technologies% the transmission cost is re#"ce#.DWDM2lectrical &egenerator1ight 0mplifierWDM Pro#"cts Deploy in .et'or!Me$r) ')re A**re*a$e 4ayerC&S&&0SS'itchDS10MSplitterO1TMS052nterprise C"stomer359:5 ase statione.S85WS85WSC9&.C2nterprise C"stomer2nterprise C"stomerFTT;W10.7PTV DC.7nternet7nternet &a#i"s Ser(erm"lticast2P5Ser(erWDM 5e"l)y i# #e$w)r6PT78IP 1A7 MSTPi, 7e$w)r6 9ac6!)#e:0,100GOT7008:0,100GOT700,10GOT7e.e.e. OADMOTMO;'O;'l1l3l.l1l3l.lilil!l!DWDM De(elopment Tren#F"llopticalnet'or!isthe#e(elopmenttren#ofopticaltransport net'or!. DWDM De(elopment Tren#S+s$ai#a!le I#$elli*e#$ 4ar*e 'a"aci$yr). 10G $)000GM+l$i-Services access +i".e#$ "r)$ec$i)#WASO7 "r)$ec$i)#< 1arge transparent transmission capacity greatly sa(es fiber reso"rces.< Thro"ghs"per8long#istancetransmissiontechnologies%thetransmissioncostis re#"ce#.ContentWDM O(er(ie'O"$ical i!er Tra#s.issi)#charac$erKey technologies of DWDMTechnical SpecificationsOptical Fiber = Type CoatingCladdingCoren2n1Opticalfiberconsistsofacylin#rical glasscore%aglasscla##ingan#a plastic 'ear8resisting coating. ' 4' S'Transport Characteristics of Optical Fibers7)#-li#er 2%%ec$Dis"ersi)#A$$e#+a$i)#1. 0tten"ation7t is the re#"ction of signal strength or light po'er o(er the length of the light8carrying me#i"m. Fiber atten"ation is meas"re# in #ecibels per !ilometer )#9!m*.7ntrinsic = 7mp"rity 0bsorbency 0tten"ationScattering 0bsorbency 0tten"ation0##itional 0tten"ation66 1666 1366 1?66 1@661anb#a nm Fiber 1oss#9!m A1?6T$BA46T$BO$8 assimilate pea!O$8O$8O 2SC 177 7 777 7V V:501@10

1550 assimilate pea!O 9a#5 Original 13@681:@6 nm2 9a#5 2,ten#e# 1:@681?@6 nmS 9a#5 Short 1?@6814:6 nm' 9a#5 Con(entional 14:6814@4 nm4 9a#5 1ong 14@481@34 nm& 9a#5 -ltra8long 1@3481@C4 nm assimilate pea!Di(ision of 1o'8loss Win#o' 2DA9a#5wi5$h1.3 1.: 1.? 1.4 1.@ 1.CWa(elength )nm*0tten"ation )#

9!m*6.16.36.?6.>1.668368161636Dispersion )ps9nm8!m* 0tten"ationSMDS7ADB7AD-G.652G.65@G.655BG.655-Feat"re Comparison bet'een 1o'81oss Win#o's Win#o' 7 77 777 7V VMar! )nm* >46 1:16 )O ban#* 1446 )C ban#* 1@66 )1 ban#*1:@6 A 14:6 )2 D S ban#s*Wa(elength range )nm*@66AE66 13@6A1:@6 14:6A14@4 14@4A1@34 1:@6A14:6Fiber type MMF MMF95.@4395.@4: 5.@4395.@4:95.@445.@4395.@4:95.@44F"ll8'a(e fiber 0pplicationsShort #istance an# lo' rateShort #istance an# lo' rate1ong #istance an# high rateDispersiontimepo'er7np"t optical p"lseSMFtimepo'erO"tp"t optical p"lse0s the optical p"lse signals are transmitte# for long #istance% the p"lse 'a(e shape sprea#s by time at the fiber o"tp"t en#% this phenomenon is calle# #ispersion.Dis"ersi)#Kin# of Dispersion'D ---- 'hr).a$ic Dis"ersi)#PMD ---- P)lariCa$i)# M)5e Dis"ersi)# TChromatic DispersionOptical signals of #ifferent 'a(elength ha(e #ifferent spee#s in the optical fiber% an# this 'ill ca"se a phenomena calle# #ispersion.Chromatic #ispersion is the res"lt of material #ispersion% 'a(eg"i#e #ispersion.1 0 1 0 1 0 1 1 0 11 0 1 0 1 0 1 1 0 1InputOutputTimeTime7nfl"ences of Chromatic Dispersion1* P"lse sprea#ing 0 maFor infl"ence of chromatic #ispersion to system performance. When transmission #istance is longer than fiber #ispersion length% p"lse sprea#ing is too large. 0t this time% the system 'ill ha(e serio"s inter8symbol interference an# bit errors. 3* Chirp effectDispersion not only res"lts in p"lse sprea#ing b"t also ma!es p"lse generate phase mo#"lation. S"ch phase mo#"lation ma!es #ifferent parts of the p"lse ma!e #ifferent offset from the central freG"ency 'ith #ifferent freG"encies.Dispersion ToleranceParameter of #ispersion tolerance for laser so"rce )Ds*Dispersion parameter for optical fiber )D*1ongest transmission #istance+ Ds9D 2,ample7f Ds H 13>66 ps9nm% SMF 5.@43 #ispersion is D H 36 ps9!m9nm an# then the longest transmission #istance of this optical so"rce is @?6!m. PolariBation Mo#e DispersionThis problem occ"rs beca"se the fiber is not consistent along its length. D"e to ben#ing an# t'isting% as 'ell as temperat"re changes% the fiber core is not e,actly circ"lar. The res"lt is that the mo#es in the fiber e,change po'er 'ith each other in a ran#om fashion #o'n the fiber length% 'hich res"lt in #ifferent gro"p (elocitiesI the signal brea!s "p. 7n effect% the light tra(els faster on one polariBation plane than another.D"e to geometrical an# press"re asymmetry% t'o polariBation mo#es ha(e #ifferent transmission rates% res"lting in #elay an# PMD.7n #igital transmission system% PMD 'ill res"lt in p"lse separation an# p"lse sprea#ing% #egra#e transmission signal an# limit transmission rate of carriers.)+r Wave Mi,i#* +aliCa$i)# %)r each cha##el G!e$$er s"ec$r+. charac$eris$ic.Spectr"m &eG"irements for OM9ODO"$ical A."li%ier Tech#)l)*yOptical 0mplifier7ts #e(elopment o(ercame the biggest barrier on high spee# long #istance transmission 8 recei(ing optical po'er limit.7t amplifies all the 'a(elength at once an# 'itho"t optical8electrical8optical con(ersion.Classifications of Optical 0mplifierSemicon#"ctor O0K&esonance TypeProgressi(e Wa(e TypeFiber amplifier1anthanon Dope# F0.on8linear F01446 nm fiber amplifier )2DF0*1:16 nm fiber amplifier )PDF0*&aman F0 )S&0*rillo"in F0 )S0*KKKK2DF0 Composition-se#tos"ppresslight reflectiontoens"re stable'or!ingofthe optical amplifier Theopticalsignalstim"lates the"nstable2rbi"mionsto releasethee,cessenergyas photonsinphasean#atthe same 'a(elength.0s this process contin"es #o'n thefiber%thesignalgro's stronger.5eneratesp"mplightthat stim"lates the erbi"m atomstoreleasetheirstore#energy as a##itional 1446 nm-se#tocombine signallight'ith p"mp light Is)la$)r')+"lerIs)la$)r2r!i+.D)"e5 i!erPI7PO&TP+."4aserP"mplightistypically 1?>6 nm or E>6 nm Wor!ing Principle980 nmpump light1550 nmsignal light1480nm1550 nmstimulatedemissionN1N3~0N22rbi"m Dope# Fiber 0mplifier )2DF0*2DF0 incl"#es+Optical ooster 0mplifier )O0* 8 high optical o"tp"t po'erOptical 1ine 0mplifier )O10* 8 compensate the loss of the transmission lineOptical Pre 0mplifier )OP0* 8 lo' noise12n OBA12n OLAOPAOLAOMUOMUKey Performance 7n#ices1.5ain )5*The ratio bet'een o"tp"t optical signal po'er an# inp"t optical signal po'er.3..oise Fig"re ).F*The ratio bet'een S.& at 2DF0 inp"t en# an# S.& at o"tp"t en#.:.an#'i#thThe 'or!ing 'a(elength range of DWDM system co(ers C an# 1 ban#s. The optical amplifier nee#s to amplify all the m"ltiple,ing channel signals of the system% so its ban#'i#th sho"l# be 'i#e eno"gh.?.5ain flatnessThe allo'e# fl"ct"ation of 2DF0 gain 'ithin the specifie# 'or!ing ban# range. For the sa!e of so"n# flatness% al"min"m #ope# technology is "s"ally "se# in the 2DF.Key Performance 7n#ices1520 1525 1530 1535 1540 1545 1550 1555 1560 1565 1570-50-40-30-20-10010wavelength/nmspectrum/dbmoutput spectrum of EDFA,Psignal=93.2766 PASE+=0.56514 Ptotal=93.8417mw1520 1525 1530 1535 1540 1545 1550 1555 1560 1565 1570-45-40-35-30-25-20-15-10-505wavelength/nmspectrum/dbmoutput spectrum of EDFA,Psignal=81.3068 PASE+=0.46032 Ptotal=81.7671mw9e%)re +si#* Gai# %la$#essA%$er +si#* Gai# %la$#essKey Performance 7n#ices?.Total inp"t9o"tp"t po'er rangeThe optical po'er range at the inp"t9o"tp"t en# of the 2DF0 .4.7np"t9o"tp"t optical reflectance The ratio bet'een optical po'er at the 2DF0 inp"t9o"tp"t en# an# reflection optical po'er.Problems of 2DF0.on8liner effectan#'i#thOptical s"rgeDispersionProblems of 2DF01. .on8linear effectWhen the optical po'er is increase# to a certain #egree% fiber non8linear effect 'ill occ"r. Therefore% in the "se of fiber amplifier% it is reG"ire# to control the (al"e of the in8fiber optical po'er in a single channel.3. an#'i#than#'i#th refers to the range of the optical 'a(elength 'hich can be amplifie# flatly. The 'or!ing 'a(elength range of the 2DF0 in C ban# is 14:6 nm A 14@1 nm% an# in 1 ban# is 14@4 nm A 1@34 nm. Contin"ation:. Optical s"rge-n#er normal con#ition% the erbi"m ions stim"late# by the p"mp light are carrie# off by the signal light% an# th"s implement amplification of the signal light. 7f the signal light is interr"pte#% the metastable ions still con(erge contin"o"sly% so energy transient 'ill occ"r lea#ing to optical s"rge.To sol(e this% 0"tomatic Po'er &e#"ction )0P&* or 0"tomatic Po'er Sh"t#o'n )0PSD* f"nction is implemente# in the 2DF0.Contin"ation?. Dispersion0s transmission #istance increase% the total #ispersion increases correspon#ingly. Therefore% the c"rrent8free relay segment in WDM system cannot be prolonge# limitlessly. We can prolong the c"rrent8free relay #istance of the m"ltiple,ing section thro"gh #ispersion compensation meas"res.S+"ervisi)# Sys$e. Tech#)l)*yS"per(ision SystemDetection% control an# management are basic reG"irements of all net'or! operations.To ens"re sec"re operation of DWDM system% physically% the monitoring system is #esigne# as an in#epen#ent system separate# from 'or!ing channels an# #e(ices.-se# to transmit the .2 management an# s"per(ision information relate# to DWDM systemF"nctions1. Fa"lt alarm3. Fa"lt location:. L"ality parameter s"per(ision in the operation?. Control o(er bac!"p line "pon line interr"ption4. 2DF0 s"per(ision. &eG"irements of OSC1. 7t cannot restrict the optical 'a(elengths )E>6 nm an# 1?>6 nm* of the p"mp light so"rce in the optical amplifier.3. 7t cannot restrict the transmission #istance bet'een t'o 10s.:. 7t cannot restrict the ser(ices on the 1:16 'a(elength.?. 7t sho"l# still be a(ailable "pon fail"re of the 10. 4. OSC transmission is bi#irectional to ens"re the s"per(ision information can be recei(e# by the line terminal 'hen one fiber is bro!en. @. OSC transmission segment can be #roppe# on each optical amplifier relay station an# DWDM system office station an# a##e# 'ith ne' s"per(ision signals. OM& OD&O9AOPAOPAO9AOD& OM&O4AO4AO4AO4AO4AO4AOS' OS' OS'OS' OS'OS' OS'OS'OS'OS'Optical S"per(ision Control )OSC*3M OSC1416nmSignal spee# + 3.6?>Mb9s&ecei(ing sensiti(ity + 8?>#bmTransmission po'er + 6 A 8C #bmContentWDM O(er(ie'Optical Fiber TransmissioncharacterKey Technologies of DWDMTech#ical S"eci%ica$i)#sDWDM Technical Specifications7ntegrate# DWDM System Open DWDM SystemWor!ing Wa(elengthMain Optical Parameter OT&(O"$ical Tra#s")#5er i$OM&( O"$ical M+l$i"le,i#* i$I#$e*ra$e5OM&G.692O"e#OT&G.692155MSDH622MSDH2.5G SDH10G SDHPDHIPATM155MSDH622MSDH2.5G SDH10G SDHPDHIPATM7ntegrate# System = Open SystemWor!ing Wa(elength in 1446nm Win#o'Wor!ing Wa(elength of DWDM System:8168@2800-wavele#*$h sys$e.Wor!ing 'a(elength range+ C ban# )14:6 nm A 14@4 nm*FreG"ency range+ 1E3.1 T$B A 1E@.6 T$B Channel inter(al+ 166 5$BCentral freG"ency offset+ M36 5$B )at rate lo'er than 3.4 5bit9s*I M13.4 5$B )at rate 16 5bit9s*Wa(elength 0llocation of ?6C$91665$B 7nter(al on C an#.o. Central FreG"ency )T$B* Wa(elength )nm*1 1E3.1 14@6.@13 1E3.3 144E.CE: 1E3.: 144>.E>? 1E3.? 144>.1C4 1E3.4 144C.:@@ 1E3.@ 144@.44C 1E3.C 1444.C4> 1E3.> 144?.E?E 1E3.E 144?.1:16 1E:.6 144:.::11 1E:.1 1443.4313 1E:.3 1441.C31: 1E:.: 1446.E31? 1E:.? 1446.1314 1E:.4 14?E.:31@ 1E:.@ 14?>.411C 1E:.C 14?C.C31> 1E:.> 14?@.E31E 1E:.E 14?@.1336 1E?.6 14?4.:3Wa(elength 0llocation of ?6C$91665$B 7nter(al on C an#31 1E?.1 14??.4:33 1E?.3 14?:.C:3: 1E?.: 14?3.E?3? 1E?.? 14?3.1?34 1E?.4 14?1.:43@ 1E?.@ 14?6.4@3C 1E?.C 14:E.CC3> 1E?.> 14:>.E>3E 1E?.E 14:>.1E:6 1E4.6 14:C.?6:1 1E4.1 14:@.@1:3 1E4.3 14:4.>3:: 1E4.: 14:4.6?:? 1E4.? 14:?.34:4 1E4.4 14::.?C:@ 1E4.@ 14:3.@>:C 1E4.C 14:1.E6:> 1E4.> 14:1.13:E 1E4.E 14:6.::?6 1E@.6 143E.44Wor!ing Wa(elength of DWDM System:0-wavele#*$h sys$e.Wor!ing 'a(elength range+ C ban# )14:6 nm A 14@4 nm*FreG"ency range+ C ban# )1E3.64 T$B A 1E@.64 T$B* Channel inter(al+ 46 5$BCentral freG"ency offset+ M4 5$BWa(elength 0llocation of >6C$9465$B 7nter(al on C an#.o. Central FreG"ency )T$B* Wa(elength )nm*1 1E@.64 143E.1@ 3 1E@.66 143E.44 : 1E4.E4 143E.E? ? 1E4.E6 14:6.:: 4 1E4.>4 14:6.C3 @ 1E4.>6 14:1.13 C 1E4.C4 14:1.41 > 1E4.C6 14:1.E6 E 1E4.@4 14:3.3E 16 1E4.@6 14:3.@> 11 1E4.44 14::.6C 13 1E4.46 14::.?C 1: 1E4.?4 14::.>@1? 1E4.?6 14:?.3414 1E4.:4 14:?.@?1@ 1E4.:6 14:4.6?1C 1E4.34 14:4.?:1> 1E4.36 14:4.>31E 1E4.14 14:@.3336 1E4.16 14:@.@1Wor!ing Wa(elength of DWDM System160-wavele#*$h sys$e.Wor!ing 'a(elength range+ C ban# )14:6 nm A 14@4 nm* D 1 ban# )14@4 nm A 1@34 nm*FreG"ency range+ C ban# )1E3.1 T$B A 1E@.6 T$B* D 1 ban# )1E6.E6 T$B A 1>@.E4 T$B* Channel inter(al+ 46 5$BCentral freG"ency offset+ M4 5$BOptical Parameter Po'erWatt )W*The "nit of po'er. 7n optical transmission% po'er is small% hence% it is e,presse# in milli'att )mW*.Decibel )#*The logarithmic ratio bet'een the o"tp"t po'er to the inp"t po'er. # H16log16 )PO-TP-T 9 P7.P-T*#mMeas"rement of po'er in #ecibels "sing 1mW as the reference point.Po'er in #m H16log16 )P 9 1mW*Optical Parameter 0tten"ationi!er Ty"e M+l$i.)5e Si#*le.)5eWa(elength )nm* >46 1:16 1:16 14460tten"ation Coefficient )#9!m*:A:.4 1A1.4 6.:A6.? 6.3A6.34Cable 1ength )!m* 3 3 3 3Total Fiber 1oss )#* @AC 3A: 6.@A6.> 6.?A6.4Optical Parameter 5ainP1 P30mplifer0mplifer 5ainHP39P1Optical Parameter OS.&OSNR:Optical signal-to-noise ratioOSNR = Pout 10log(M - L + 58 - N! - 10logNPout: "n-#i$er optical po%er (&'(!)M: Nu($er o# (ultiple*ing c+annels o# t+e ,-M s.ste( L: Loss $et%een an. t%o optical a(pli#iers/ t+at is/ sectional loss (&'! N: Noise in&e* o# t+e 0-1) N: Nu($er o# t+e 0-1s $et%een optical (ultiple*er an& optical &e-(ultiple*er o# t+e ,-M s.ste()