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B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 1 MC LC MC LC ........................................................................................................................... 1 Danh mc hnh v ............................................................................................................... 4 LI NI U ..................................................................................................................... 7 CHNG I : TNG QUAN V H THNG THNG TIN QUANG WDM ............ 8 1.1.Gii thiu chung .................................................................................................... 8 1.2.S khi tng qut ............................................................................................. 8 1.3Phn loi h thng WDM ..................................................................................... 9 1.4Cc phn t c bn trong h thng WDM ....................................................... 10 1.4.1B pht quang ................................................................................................ 10 1.4.2B thu quang .................................................................................................. 12 1.4.3Si quang ........................................................................................................... 13 1.4.4.B tch / ghp bc song: ( OMUX/ODEMUX) ............................................. 14 1.4.5. B xen / r bc sng: ( OADM) ...................................................................... 15 1.4.6.B ni cho quang: (OXC) ............................................................................ 17 1.4.7.B khuch i quang: (OA -Optical Amplifier): ......................................... 18 1.4.8.B chuyn i bc song ............................................................................... 19 1.5.Cc tham s c bn ca gp knh quang theo bc sng ............................... 20 1.5.1 Suy hao xen ......................................................................................................... 20 1.5.2.Xuyn knh .................................................................................................... 20 1.5.3. rng knh .................................................................................................. 22 1.5.4.nh hng ca cc hiu ng phi tuyn .......................................................... 23 1.6.Cu trc mng truyn ti quang ......................................................................... 24 1.6.1. Cu trc mng Ring ........................................................................................... 24 1.6.2. Cu trc mng Mesh .......................................................................................... 24 1.6.3. Cu trc mng hnh sao ..................................................................................... 25 1.6.4. Cu trc mng Mesh v Ring hai lp ................................................................ 26 1.7u nhc im ca h thng WDM ................................................................. 27 1.8B khuch i quang EDFA .............................................................................. 27 1.8.1 Cc cu trc EDFA ............................................................................................. 27 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 2 1.8.2 L thuyt khuch i trong EDFA...................................................................... 29 1.8.3 Yu cu i vi ngun bm................................................................................ 31 1.8.4Ph khuch i ................................................................................................... 33 1.8.5. Cc tnh cht ca EDFA .................................................................................... 34 1.8.6. Nhiu trong b khuch i ................................................................................. 36 1.8.7 u khuyt im ca EDFA ................................................................................ 38 CHNG II M PHNG TUYN THNG TIN QUANG WDM BNG PHN MM OPTISYSTEM ....................................................................................................... 39 2.1. Tng quan v phn mm Optisystem ................................................................... 39 2.1.1. Li ch ................................................................................................................ 39 2.1.2. ng dng ........................................................................................................... 40 2.2. c im v chc nng .......................................................................................... 40 2.2.1. Cu to th vin (Component Library) .............................................................. 40 2.2.2. Tch hp vi cc cng c phn mm Optiwave ................................................ 41 2.2.3. Cc cng c hin th .......................................................................................... 42 2.3. Tm tt hng dn s dng phn mm optisystem ........................................... 42 2.3.1. Yu cu chung ................................................................................................... 42 2.3.2 Hng dn s dng phn mm optisystem ...................................................... 45 2.3.3 To mt d n mi .............................................................................................. 50 2.3.4. Hin th v thay i tham s ca cc phn t trong d n................................. 52 2.3.5. Chy m phng .................................................................................................. 58 2.4. M hnh m phng ................................................................................................. 66 2.4.1 Yu cu thit k ................................................................................................... 66 2.4.2 M phng theo phng n thit k ..................................................................... 68 2.4.2.1 Tuyn pht quang: chn ca s truyn 1550nm EDFA bng C ............... 68 2.4.2.2 Tuyn truyn dn quang ............................................................................... 71 2.4.4.3 Tuyn thu ca h thng WDM ...................................................................... 74 2.4.3 Kt qu m phng theo yu cu thit k ............................................................ 75 2.4.4. Kt qu m phng thay i cc tham s t BER=10-12 .............................. 79 Ti Liu Tham Kho.......................................................................................... 83 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 3 THUT NG V T VIT TT GVDGroup velocity dispersionNhm h s tn sc OADMOptical add/drop multiplexerB xen rt quang BERBit error rateTc li bit OTNOptical transport networkMng truyn ti quang DCFDispersion sompensating fiberSi b tn sc DEMUXDemultipplexerB tch knh SNRSignal to noise ratioT s tn hiu trn nhiu EDFAErbium doped fiber amplifier Khuchiquangsiquangtrn Erbium FWMFour wave mixingHiu ng trn bn sng LASER Lightamplicationbystimulated emission of radiation Khuchinhsngnhbcx kch thch MUXMultiplexerB ghp knh NFNoise figureNn nhiu SBSStimulated brillouin scatteringTn x do kch thch Brillouin CATVCable televisionCp tivi OLTOptical line terminalB u cui ng quang OSCOptical supervisory channelKnh gim st ng quang EDFErbium doped fiber Siquangphaionthim Erbium OXCOptical cross connectorB kt ni cho quang PMDPolarisation mode dispersionH s tn sc phn cc mode APSAutomatic protection switchingChuyn mch bo v t ng PONPass optical networkMng quang th ng WDMWavelength devision MultiplexingGhp knh theo bc sng SMFSingle mode fiberSi n mode TDMTime division multiplexing Bghpknhphnchiatheothi gian SPMSelf phase modulationHiu ng t iu ch dch pha B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 4 Danh mc hnh v Hnh 1.1: S chc nng h thng WDM ............................................................ 6 Hnh 1.2: H thng ghp bc sng n hng v song hng ...................................... 6 Hnh 1.3 : S b iu ch ngoi ................................................................................... 8 Hnh 1.4 : S khi bn thu ............................................................................................ 9 Hnh 1.5 : Cu trc tng qut si quang ........................................................................... 10 Hnh 1.6. S khi b ghp/ tch knh bc sng ......................................................... 11 Hnh 1.7 Cu trc song song ............................................................................................. 12 Hnh 1.8 : Cu trc song song theo bng .......................................................................... 12 Hnh 1.9 : Cu trc ni tip ............................................................................................... 13 Hnh 1.10 : Cu trc xen rt theo bng sng .................................................................... 13 Hnh 1.11 : S kt ni OXC .......................................................................................... 14 Hnh 1.12 : Khuch i quang OLA .................................................................................. 15 Hnh 1.13: Xuyn knh b gii ghp .............................................................................. 18 Hnh 1.14: Xuyn knh b ghp hn hp ....................................................................... 18 Hnh 1.15 : Cu trc mng Ring ....................................................................................... 21 Hnh 1.16 : Cu trc mng Mesh ...................................................................................... 21 Hnh 1.17 : Cu trc mng hnh sao n .......................................................................... 22 Hnh 1.18: Cu trc mng hnh sao kp ........................................................................... 22 Hnh 1.19 : Cu trc mng hnh Ring hai lp ................................................................... 23 Hnh 1.20: Cu trc tng qut ca mt b khuch i EDFA .......................................... 24 Hnh 1.21: Mt ct ngang ca mt loi si quang pha ion Erbium ................................. 25 Hnh 1.22: Gin phn b nng lng ca ion Er3+ trong si silica .......................... 26 Hnh 1.23 Ph hp th ...................................................................................................... 27 Hnh 1.24: Qu trnh khuch i tn hiu ......................................................................... 28 Hnh 1.25: Cu hnh b khuch i EDFA c bm kp [11]. ...................................... 30 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 5 Hnh 1.26 Cu hnh ca mt b khuch bng L ................................................................ 31 Hnh 1.27: th biu din cng sut ra bo ho. .......................................................... 33 Hnh 1.28 (a) H s nhiu FN v (b) li ca EDFA ................................................... 34 Hnh 2.1: Thnh phn trnh din ....................................................................................... 42 Hnh 2.2: Th vin cc phn t ......................................................................................... 42 Hnh 2.3: Giao din th vin ............................................................................................. 44 Hnh 2.4. Giao din ngi s dng ................................................................................... 44 Hnh 2.5: Project Browser ................................................................................................. 45 Hnh 2.6: Description ........................................................................................................ 45 Hnh 2.7: Status bar ........................................................................................................... 46 Hnh 2.8: Menu bar ........................................................................................................... 46 Hnh 2.9: Pan window ....................................................................................................... 46 Hnh 2.10: Tool bars ......................................................................................................... 47 Hnh2.11. Ca s Project layout ....................................................................................... 47 Hnh 2.12. t phn t vo Main layout ........................................................................... 48 Hnh 2.13: Kch hot kt ni t ng ................................................................................ 48 Hnh 2.14:Hy b ch kt ni t ng ......................................................................... 48 Hnh2.15 :mn hnh Parameters ..................................................................................... 49 Hnh 2.16 :Chn trng thay i tc bt ...................................................................... 50 Hnh 2.17 : Nhptc bt mun thay i ...................................................................... 51 Hnh2.18 : Thit lp ca s thi gian thc ....................................................................... 52 Hnh 2.19 : Thay i cng sut pht quang ...................................................................... 53 Hnh 2.20: Giao din mn hnhchy m phng........................................................... 55 Hnh 2.21 : Chychng trnh ........................................................................................ 56 Hnh 2.22: o t s BER ca knh .................................................................................... 57 Hnh 2.23 : Kt qu m phng......................................................................................... 58 Hnh 2.24: Thit lp tham s quyt ................................................................................... 59 Hnh2.25: Chuyn i s ln qut. ................................................................................. 60 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 6 Hnh 2.26: Hp thoi chuyn sang ch qut cho tham s........................................... 61 Hnh2.27: Chn ch ca tham s ............................................................................... 61 Hnh 2.28:. Cc bc hin th kt qu m phng qut tham s ................................... 63 Hnh 2.29: Thit lp tham s ton cc .............................................................................. 65 Hnh 2.30: Ngun Laser pht CW Laser ........................................................................... 66 Hnh 2.31: B to xung RZ ................................................................................................ 66 Hnh 2.32. B to chui bt ............................................................................................... 66 Hnh 2.33: B iu ch Mach-Zehnder ............................................................................. 67 Hnh 2.34:B ghp knh MUX 41. ............................................................................... 67 Hnh 2.35: Tuyn pht quang ............................................................................................ 68 Hnh 2.36. Tuyn truyn dn quang .................................................................................. 68 Hnh 2.37.B lp .............................................................................................................. 69 Hnh 2.38. Thng s si b tn sc DCF .......................................................................... 70 Hnh 2.39. Tuyn thu WDM ............................................................................................... 71 Hnh 2.40. Thit b o BER ............................................................................................... 71 Hnh 2.41.Tuyn WDM thit k theo yu cu .................................................................. 72 Hnh 2.42. Quang ph tn hiu pht .................................................................................. 73 Hnh 2.43. Quang ph tn hiu u thu knh th 3. ..................................................... 73 Hnh 2.44. Tng cng sut pht ........................................................................................ 74 Hnh 2.45. Cng sut thu ca knh 4. ......................................................................... 74 Hnh 2.46.Hin th mt quang ......................................................................................... 75 Hnh 2.47. BER ca knh th nht l 10-13 ........................................................................................................... 75 Hnh 2.48. Thay i cng sut Laser pht ........................................................................ 76 Hnh 2.49. H s suy hao si quang thay i .................................................................... 76 Hnh 2.50. BER ca knh th nht t 10-12 ........................................................................................................ 77 Hnh 2.51. BER t 10-12 khi thay i mt s tham s ...................................................... 77 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 7 LI NI U Visphttrinvcngmnhmcacngnghthngtinnichungvk thut vin thng ni ring. Nhu cu dch v vin thng pht trin rt nhanh to ra p lcngycngcaoivitngdunglngthngtin.Cngvisphttrincak thut chuyn mch, k thut truyn dn cng khng ngng t c nhng thnh tu to ln, c bit l k thut truyn dn trn mi trng cp si quang. Tng lai cp si quang c s dng rng ri trn mng vin thng v c coi nh l mt mi trng truyn dn l tng m khng c mt mi trng truyn dn no c th thay th c. Cchthngthngtinquangviuimbngthngrng,clyxa,khngnh hng ca nhiu v kh nng bo mt cao ,ph hp vi cc tuyn thng tin xuyn lc angtrc vctimnngtolntrongvicthc hincc chc nngcamng niht vi cc cu trc linh hot v p ng mi loi hnh dch v hin ti v tng lai.Tacththymngthngtinquanghinnayvncnmtshnchvcht lng truyn dn do bng thng cn hp, khong cch truyn dn ngn, v th yu cu t ra l phi tng cht lng cng nh c ly ng truyn cho ch thng tin quang hin nay. Gii php c a ra y l cng ngh ghp knh theo bc sng WDM, nchophpghpnhiubcsngtrncngmtsiquangdocthtngdung lng ng truyn m khng cn tng thm si quang. Vi bi ton: xy dng phng n thit k h thng thng tin quang WDM c sdngkhuchiquangEDFA.Nhmemxintrnhbytngquanvhthng thng tin quang WDM c s dng khuch i EDFA , xy dng m hnh m phng h thng thng tin quang WDM theo phng n thit k. ChngemxincgilicmnchnthnhtithygioTh.sCaoHng Sn, hng dn, gip nhm em trong thi gian qua. Mc d c gng rt nhiu, nhng do trnh cn hn ch nn s khng trnh khi nhng thiu xt. Rt mong nhn c nhng kin ng gp ca thy, cc bn bi tp ca chng em c hon thin hn. Chng Em xin chn thnh cm n! B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 8 CHNG I : TNG QUAN V H THNG THNG TIN QUANG WDM 1.1.Gii thiu chung Ghp knh theo bc sng WDM (Wavelength Devision Multiplexing) l cng ngh trong mt si quang ng thi truyn dn nhiu bc sng tn hiu quang. upht,nhiutnhiuquangcbcsngkhcnhaucthpli(ghp knh) truyn i trn mt si quang. u thu, tn hiu t hp c phn gii ra (tch knh), khi phc li tn hiu gc ri a vo cc u cui khc nhau. 1.2.S khi tng qut Phttnhiu:TronghthngWDM,ngunphtquangcdngllaser. Hinticmtsloingunphtnh:Laseriuchnhcbcsng (TunableLaser),Laserabc sng(MultiwavelengthLaser)...Yucuivi ngun pht laser l phi c rng ph hp, bc sng pht ra n nh, mc cng sutphtnh,bcsngtrungtm,rngph,rngchirpphinmtrong gii hn cho php. Ghp/tch tn hiu: Ghp tn hiu WDM l s kt hp mt s ngun sng khc nhauthnhmtlungtnhiunhsngtnghptruyndnquasiquang. Tch tn hiu WDM l s phn chia lung nh sng tng hp thnh cc tn hiu nh sng ring r ti mi cng u ra b tch. Hin ti c cc b tch/ghp tn hiu WDM nh: b lc mng mng in mi, cch t Bragg si, cch t nhiu x, linhkinquangthpAWG,blcFabry-Perot...Khixtnccbtch/ghp WDM, ta phi xt cc tham s nh: khong cch gia cc knh, rng bng tn caccknhbcsng,bcsngtrungtmcaknh,mcxuynmgiacc knh, tnh ng u ca knh, suy hao xen, suy hao phn x Bragg, xuyn m u gn u xa... Truyn dn tn hiu: Qu trnh truyn dn tn hiu trong si quang chu s nh hng ca nhiu yu t: suy hao si quang, tn sc, cc hiu ng phi tuyn, vn lin quan n khuch i tn hiu ... Mi vn k trn u ph thuc rt nhiu vo yu t si quang (loi si quang, cht lng si...). Khuchitnhiu:HthngWDMhintichyusdngbkhuchi quangsiEDFA(Erbium-DopedFiberAmplifier).Tuynhinbkhuchi Ramanhinnaycngcsdngtrnthct.Cbachkhuchi: B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 9 khuchicngsut,khuchingvtinkhuchi.Khidngbkhuch i EDFA cho h thng WDM phi m bo cc yu cu sau: -likhuchi ng uivi tt cccknhbcsng(mcchnh lch khng qu 1 dB).-Sthayislngknh bcsng lmvickhngcgynhhng n mc cng sut u ra ca cc knh.-C kh nng pht hin s chnh lch mc cng sut u vo iu chnh li cc h s khuch i nhm m bo c tuyn khuch i l bng phng i vi tt c cc knh. Thu tn hiu: Thu tn hiu trong cc h thng WDM cng s dng cc b tch sng quang nh trong h thng thng tin quang thng thng: PIN, APD. Hnh 1.1: S chc nng h thng WDM 1.3Phn loi h thng WDM Hnh 1.2: H thng ghp bc sng n hng v song hng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 10 H thng WDM v c bn chia lm hai loi: h thngn hng v song hng nh minh ho trn hnh 1.2. H thng n hng ch truyn theo mt chiu trn si quang. Do vy,truynthngtingiahaiimcnhaisiquang.HthngWDMsonghng, ngc li, truyn hai chiu trn mt si quang nn ch cn 1 si quang c th trao i thng tin gia 2 im.Chaihthngucnhngunhcimring.Gisrngcngnghhinti ch cho php truyn N bc sng trn mt si quang, so snh hai h thng ta thy:- Xtvdunglng,hthngnhngckhnngcungcpdunglngcaogp isovihthngsonghng.Ngcli,ssiquangcndnggpisovih thng song hng.- Khi s c t cp xy ra, h thng song hng khng cn n c ch chuynmch bo v t ng APS (Automatic Protection-Switching) v c hai u ca lin kt u c kh nng nhn bit s c mt cch tc thi.- ng v kha cnh thit k mng, h thng song hng kh thit k hn v cn phi xtthmccyutnh:vnxuynnhiudocnhiubcsnghntrnmtsi quang,mbonhtuynvphnbbcsngsaochohaichiutrnsiquang khng dng chung mt bc sng.- Cc b khuch i trong h thng song hng thng c cu trc phc tp hn trong hthngnhng.Tuynhin,dosbcsngkhuchitronghthngsong hnggimtheomichiunnhthngsonghng,ccbkhuychischo cng sut quang ng ra ln hn so vi h thng n hng. 1.4Cc phn t c bn trong h thng WDM 1.4.1B pht quang Cc ngun quang c bn s dng trong h thng thng tin cp si quang c th l Diode Laser (LD) hoc Diode pht quang (LED). LaserLightAmplicationbyStimulatedEmissionofRadiationKhuchi nhsngnhbcxkchthch.HotngcaLaserdatrnhaihintngchnhl: Hin tng bc x kch thch v hin tng cng hng ca sng nh sng khi lan truyn trong Laser. Tn hiu quang pht ra t LD hoc LED c cc tham s bin i tng ng vi binicatnhiuinvo.Tnhiuinvocthphtdngshoctngt. Thit b pht quang s thc hin bin i tn hiu in vo thnh tn hiu quang tng ng bng cch bin i dng vo qua cc ngun pht quang. Bc sng nh sng ca ngun pht quang ph thuc ch yu vo vt liu ch to phn t pht. V d GaalAs pht ra bc B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 11 xvngbcsng800nmn900nm,InGaAsPphtrabcxvng1100nmn 1600 nm. S dng b iu bin ngoi gim chirp, tc iu bin cao v to cc nh dng tn hiu quang khc nhau (NRZ, RZ, CS-RZ, DPSK ) v m bo tn hiu quang c rng ph hp ti bc sng chnh xc theo tiu chun. - M hnh iu ch ngoi Hnh 1.3 : S b iu ch ngoi - Yu cu vi ngun quang: - chnh xc ca bc sng pht: y lyu cu kin quyt cho mt h thng WDM hot ng tt. Ni chung, bc sng u ralun bdao ng do cc yu t khc nhaunhnhit,dngnhthin,giholinhkin...Ngoira,trnhxuyn nhiu cng nh to iu kin cho pha thu d dng tch ng bc sng th nht thit n nh tn s pha pht phi tht cao. - rng ng ph hp: rng ng ph c nh ngha l rng ph ca ngunquangtnhchobcct3dB.cthtngnhiuknhtrnmtditncho trc, cng vi yu cu khong cch cc knh nh cho nn rng ng ph cng hp cngtt,nukhng,xuynnhiuknhlncnxyrakhinlibttngcao,hthng khngmbochtlng.Muntciunythngunphtlaserphilngun nmode(nh cc loi laser hi tip phnb, laserhai khoang cng hng, laserphn hi phn b). - Dng ngng thp: iu ny lm gim bt vn lng ph cng sut trong vic kch thch laser cng nh gim bt c cng sut nn khng mang tin v trnh cho my thu chu nh hng ca nhiu nn (pht sinh do c cng sut nn ln). B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 12 - Kh nng iu chnh c bc sng: tn dng ton b bngtn si quang, ngun quang phi c th pht trn c di 100 nm. Hn na, vi h thng la knh ng cng cn kh nng c th iu chnh c bc sng. - Tnh tuyn tnh: i vi truyn thng quang, s khng tuyn tnh ca ngun quang s dn vic pht sinh cc sng hi cao hn, to ra cc xuyn nhiu gia cc knh. - Nhiu thp: C rt nhiu loi nhiu laser bao gm: nhiu cnh tranhmode, nhiu pha,... Nhiu thp rt quan trng t cmc BER thp trong truyn thng s, m bo cht lng dch v tt. 1.4.2B thu quang Phnthuquanggmccbtchsngquang,knhtuyntnhvknhphchi.N tip nhn tnhiu quang, tch ly tn hiu thu c t pha pht, bin i thnh tn hiu in theo yu cu c th. Trong phn ny thng s dng cc photodiode PIN hoc APD. Yu cu quan trng nht i vi b thu quang l cng sut quang phi nh nht ( nhy quang) c th thu c mt tc truyn dn s no ng vi t l li bt (BER) cho php. B thu quang trong h thng WDM Hnh 1.4 : S khi bn thu B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 13 1.4.3Si quang Cu to si quang ng dng hin tng phn x ton phn, si quang c ch to c bn gm c hai lp:-Lp trong cng c dng hnh tr trn, c ng knh d = 2a, lm bng thy tinh c chit sut n1, c gi l li (core) si. -Lpthhaicngcdnghnhtrbaoquanhlinncgillpbc (cladding), c ng knh D = 2b, lm bng thy tinh hoc plastic, c chit sut n2 < n1. Hnh 1.5 : Cu trc tng qut si quang Phn loi si quang Phn loi theo chit sut: -Si quang chit sut bc SI (Step-Index) -Si quang chit sut bin i GI (Graded-Index) Phn loi theo mode -Si n mode (Single-Mode) -Si a mode (Multi-Mode) Si quang G652 Lsinmodecsdngphbintrnmnglivinthngnhiunchin nay. N c th lm vic 2 ca s: - ca s 1310nm: G652 c tn sc nh nht (xp x 0 ps/nm.km) v suy hao tng i ln. - ca s 1550nm: G652 c suy hao truyn dn nh nht v h s tn sc tng i ln (xp x 20ps/nm.km) Si quang G655 L mt chun v si quang c a ra bi ITU-T c cc u im sau: -Si quang G655 thch hp cho h thng DWDM, lm tng dung lng truyn dn. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 14 -Si quang G655 thchhp cho h thng truyn dn ng diWDM dung lng cao. - tn sc dng ca si G655 trnh vic trn ln 4 bc sng quang. -Vng hiu dng cao ca si G655 (vn nh hn si SMF) lm gim thiu cc hiu ng phi tuyn. -Erbium Doped Fiber Amplifier (EDFA) khuch i cc tn hiu quang trong ca s C, iu ny l tng cho loi si quang NZDS (non-zero dispersion-shifted). 1.4.4.B tch / ghp bc song: ( OMUX/ODEMUX) nhngha:Bghp/tchknhbcsng,cngvivktnichoquang,l thit b quan trng nht cu thnh nn h thng WDM. Khi dng kt hp vi b kt ni cho quang OXC s hnh thnh nn mng truyn ti quang, c kh nng truyn ti ng thi v trong sut mi loi hnh dch v, m cng ngh hin nay ang hng ti.B tch/ ghp knh thc hin ghp tch tn hiu cc bc sng khc nhau. B ghp/ tch knh bc sng thng c m t theo nhng thng s sau: -Suy hao xen -S lng knh x l -Bc sng trung tm -Bng thng -Gi tr ln nht ca suy hao xen - suy hao chen gia cc knh (a) Skhibghp knh bc sng (MUX) (b) Skhibtch knh bc sng (DEMUX) (c) Ccthamsc trng ca b MUX/ DEMUX Hnh 1.6. S khi b ghp/ tch knh bc sng Ghp tng to b ghp knh dung lng cao: -Ghp tng ni tip n knh -Ghp mt tng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 15 -Ghp tng theo tng bng sng -Ghp tng an xen chn l 1.4.5. B xen / r bc sng: ( OADM) Khi nim :-OADM(OpticalAdd/DropMultiplexer)thngcdngtrongccmng quangthvccmngquangngdivnchohiuqukinhtcao,cbiti vi cu hnh mng tuyn tnh, cu hnh mng vng. -OADMccuhnhxen/rtmtsknhbcsng,ccknhbcsng cn li c cu hnh cho i xuyn qua. Cc cu trc cho OADM : -Cutrcsongsong :ttcccknhtnhiuucgiighpknh.Sau mt s knh ty c cu hnh rt, cc knh cn li cu hnh cho i xuyn qua mt cch thch hp. Hnh 1.7 Cu trc song song -Cutrcsongsongtheobng(theomodun) :tothnhbngcchthitktheo tng modun cho cu trc song song B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 16 Hnh 1.8 : Cu trc song song theo bng -Cu trc ni tip : Mt knh n c thc hin rt v xen t tp hp cc knh i vo OADM. Hnh 1.9 : Cu trc ni tip -Cutrcxenrttheobngsng :trongcutrcnymtnhmcnhknh bc sng thc hin xen/ rt ti mi nt mng OADM. Cc knh c thit lp thc hin xen/rtlccknhlintipnhautrongmtbngsng,sclcbimtblcc bng thng l di bc sng. Sau chng c a ln mc ghp knh cao hn v t gii ghp knh thnh cc knh bc sng ring l Hnh 1.10 : Cu trc xen rt theo bng sng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 17 1.4.6.B ni cho quang: (OXC) nh ngha : OXC l thit b p ngyu cu v kh nng linh ng trong vic cung ng dch v, hay p ng kh nng p ng c s tng bng thng t bin ca cc dch v a phng tin Hnh 1.11 : S kt ni OXC Cc yu cu i vi OXC : -Cung cp dch v -Bo v -Trong sut i vi tc truyn dn bit -Gim st cht lng truyn dn -Chuyn i bc sng -Ghp v nhm tn hiu B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 18 1.4.7.B khuch i quang: (OA -Optical Amplifier):
Hnh 1.12: Khuch i quang OLA Trnthcthinnaycctuynthngtintccaongitasdngb khuchiquanglmcctrmlp,chyulccbkhuchingdyphatp Eribum(EDFA).Ccbkhuchinycuimlkhngcnqutrnhchuyni O/E v E/O m thc hin khuch i trc tip tn hiu quang.Li ch: + Thay th cc b lp t tin trong h thng b gii hn bi suy hao + Tng nhy ca b thu + Nng cao mc cng sut pht +clpvtcvnhdngtnhiu,khuchitnhiuaknh WDM ng thi OADM My thu Laser Bm Raman Laser Chng li Chng li B b tn sc OSC OSC 1 ,2 ,,W B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 19 + Nng cp n gin c tnh ca 1 s b khuch i quang l tng + H s khuch i vmc cng sut u ra cao vi hiu sut chuyn i cao. + rng bng tn khuch i ln vi h s khuch i khng i+Khng nhy cm vi phn cc+Nhiu thp+Khng gy xuyn knh gia cc tn hiuWDM +Suy hao ghp ni vi si quang thp. Phn loi : + Vo : ging nh laser bn dn nhng c phn cc di ngng+Bkhuchiquangsiphatpthim:khuchixyratrongsi quang pha tp t him, ph bin l b EDFA + Ra : khuch i xy ra trong si quang nh mc cng sut bm cao1.4.8.B chuyn i bc song B chuyn i bc sng l thit b chuyn i tn hiu c bc sng ny u vo ra thnh tn hiu c bc sng khc u ra. i vi h thng WDM, b chuyn i bc sng cho nhiu ng dng hu ch khc nhau : - Tnhiucthivomngvibcsngkhngthchhpkhitruyntrong WDM - BchuynikhictrangbtrongcccuhnhntmngWDMgips dng ti nguyn bc sng hiu qu hn, linh ng hn. - C 4 phng php ch to b chuyn i bc sng:Phng php quang in Phng php ca quang Phng php giao thoa Phng php trn bc sng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 20 1.5.Cc tham s c bn ca gp knh quang theo bc sng 1.5.1 Suy hao xen c xc nh l lng cng sut tn hao trong tuyn truyn dn quang do cc im ghpniccthitbWDMvisivsuyhaodobnthnccthitbghpgyra.V vy,trongthctthitkphitnhchovidBmiu.Suyhaoxencbiudin qua cng thc sau (xt b MUX-DEMUX m t hnh 2.7). Trong Li l suy hao ti bc sng i khi thit b c ghp xen vo tuyn truyn dn. Cc tham s ny c cc nh ch to cho bit i vi tng knh quang ca thit b. - Ii(i), Oi(i) tng ng l tn hiu c bc sng i i vo v i ra ca th i ca b ghp. - Ii(i), Oi(i) tng ng l tn hiu c bc sng i i vo v i ra ca th i ca b tch. 1.5.2.Xuyn knh Xuyn knh l s c mt ca mt knh ny trong knh k cn lm tng nn nhiu v gim t s tn hiu nhiu ca knh ang xt. Trong h thng ghp knh quang, xuyn knh xut hin do: - Cc vin ph camtknh i vobng thng ca b tch knh vb lc ca knh khc. Khi sng mang quang c iu ch bi mt tn hiu, s iu ch cng sut trong cc vin ph ca n nh l iu ch cng sut trong bng bi knh k cn. - Xut pht t nhng gi tr hu hn thc t v chn lc v cch ly ca cc b lc. - Tnhphituyntrongsiquangmccngsutcaotrongcchthngnmode. C ch ca n l tn x Raman, l hiu ng tn x kch thch phi tuyn lm cho cng sut | || | (2.2)) (log 10(2.1) ) (log 10DEMUX dBIOLMUX dBIOLi iiii iii = =B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 21 quang mt bc sng tc ng n tn x v cng sut quang, trong cc bc sng khc cng nh vy. Trong mt b tch knh s khng c s d cng sut tn hiu t knh th i c bc sng i sang knh khc c bc sng khc vi bc sng i. Nhng trong thc t lun tn ti mt mc xuyn knh no , lm gim cht lng truyn dn ca mt thit b. Kh nng tch cc knh khc nhau c din gii bng suy hao xuyn knh v c tnh bng dB nh sau:Trong b gii ghp th Ui(k) l lng tn hiu khng mong mun bc sng k b d ca ra th i m ng ra ch c tn hiu bc sng i, hnh 2.8a. Trongccthitbtchhnhpnhhnh2.8bc2loixuynmknhlxuyn m u gn v xuyn m u xa. | | dBIUDk ik ii i ((
=) () (log 10 ) ( MUX Si quang I(i) ...I(k) Oi(i) ...Ui(k) Hnh 1.13: Xuyn knh b gii ghp Ui(k)+Ui(j) I(i)...I(k) Ii(i) Oi(j) Si quang Hnh 1.14: Xuyn knh b ghp hn hp B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 22 -Xuynknhugnldoccknhkhcuvosinhra,ncghpbn trong thit b nh Ui(j). - Xuyn knh u xa l do cc knh khc c ghp i vo ng truyn gy ra, v d Ii(k) sinh ra Ui(j). 1.5.3. rng knh Mt vn quan trng i vi h thng WDM l c th s dng bao nhiu bc v vic phn chia bc sng nh th no. Hin nay trong h thng vin thng dng si quang thng s dng bc sng 1550nm v cc b khuch i EDFA. Bng thng cc i ca b khuch i si pha tp EDFA khon 30nm. Nu ta mun xp khong 16 knh trong di bc sng ny th rng gia cc knh l 30nm/16 knh hay 1,875nm. rng knh l tiu chun trong min tn s hn l bc sng. Mi quan h gia tn s v bc sng: Trong : c l vn tc nh sng 3.108 m/s. l bc sng hot ng. V vy 1,875nm l tng ng vi rng ca cc knh c tn s xp x 250GHz. Vy rng knh l di bc sng m n nh ra cho tng ngun pht quang. Di bc sng C ca cc b khuch i EDFA l 1530-1550nm. Nu ngun pht th nht pht x ti 1530, th ngun pht th hai phi pht x ti 1531,875nm v cc ngun pht khc tng t. Nu ngun pht quang l cc diode laser th rng knh yu cu khong vi chc nm. i vi ngun pht quang l diode LED yu cu rng knh phi ln hn t 10 n 20 ln LD v rng ph ca loi ngun ny rng hn. 2 2 c f cddfcfc f=AA = ==(2.4) B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 23 1.5.4.nh hng ca cc hiu ng phi tuyn Trong h thng thng tin quang, cc hiu ng phi tuyn s xy ra khi cng sut tn hiu trong si quang vt qu mt gii hn ca h thng WDM th mc cng sut ny thp hn nhiu so vi cc h thng n knh. Cc hiu ng phi tuyn nh hng n cht lng ca h thng WDM c th chia thnh hai loi l hiu ng tn x v hiu ng Kerr (khc x). a. Hiu ng tn x: Bao gm cc hiu ng SBS v SRS: - Hiu ng SRS (Stimulated Raman Scrattering) l hin tng chiu nh sng vo si quang s gy ra dao ng phn t trong vt liu ca si quang, n iu ch tn hiu quang a vo dn n bc sng ngn trong h thng WDM suy gim tn hiu qu ln, hn ch s knh ca h thng. - Hiu ng SBS (Stimulated Brillouin Scrattering) cng c hin tng nh SRS nhng gy ra dch tn v di tn tng ch rt nh v ch xut hin hng sau chiu tn x. nh hng cn ln th ngng cng sut cng thp. b. Hiu ng Kerr: Gm cc hiu ng SPM, XPM, FWM: - Hiu ng SPM (Self Phase Modulation) l hin tng khi cng quang a vo thay i, hiu sut khc x ca si quang cng thay i theo gy ra s bin pha ca sng quang. Khi kt hp vi tn sc ca si quang s dn n ph tn dn rng v tch ly theo s tng ln ca chiu di. S bin i cng sut quang cng nhanh th bin i tn s quang cng ln. - Hiu ng XPM (Cross Phase Modulation), c ngha l trong h thng nhiu bc sng v hiu sut khc x bin i theo cng u vo dn n pha ca tn hiu b iu chbi cng sut ca knh khc. - Hiu ng FWM (Four Wave Mixing) xut hin khi c nhiu tn hiu quang truyn dn hn hp trn si quang lm xut hin bc sng mi gy nn xuyn nhiu lm hn ch s bc sng c s dng. Vic ny sinh cc hiu ng phi tuyn s gy cc hin B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 24 tng xuyn m gia cc knh, suy gim mc cng sut tn hiu ca tng knh dn n suy gim t s S/N, nh hng n cht lng h thng. 1.6.Cu trc mng truyn ti quang 1.6.1. Cu trc mng Ring Hnh 1.15 : Cu trc mng Ring Cc node ch lin ktvt l trc tip vi hai node gn nhauKt ni ny thun li cho vic bo dng, hiu nng cao ,chi ph thp, s dng phn t mng mt cch hiu qu 1.6.2. Cu trc mng Mesh Hnh 1.16 : Cu trc mng Mesh Cc node lin ktvt l trc tip vi tt c node gn nCung cp nhiu kh nng nh tuynCu trc c tin cy cao nhng kt cu phc tpB mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 25 Thng c s dung trong cc mang i hi tin cy cao 1.6.3. Cu trc mng hnh sao a.Cu trc mng hnh sao n Hnh 1.17 : Cu trc mng hnh sao n Chn mt node lm trung tm tn hiu s c truyn n cc node nh hnh trn Cu trc mng n gin, cho php truyn dung lng lnNode trung tm phi c kh nng truyn v s l vi dung lng ln b.Cu trc mng hnh sao kp Hnh 1.18: Cu trc mng hnh sao kp Tng t nh mang sao n nhng ngoi node trung tm cn c cc thit b u xaB mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 26 Cu trc kp cho php s dng hiu quv mi nhnh c th c nhiu node con Cu trc ny c nhc im do s dng thit b u cui nn tng chi phlp tCu hnh phc tp cng lm gim tin cy. Kh pht trin dch v bng thng rngc.Cu trc mng hnh Ring hai lp Hnh 1.19 : Cu trc mng hnh Ring hai lp ng dng cu trc mng ring hai lp c s dng trn thc t kt ni gia cc cu trc ring ring bit tao thnh mt mang lin kt lnTc gia cc node trong mang ring th cao, ngc li tc gia cc mang ring tng i chm1.6.4. Cu trc mng Mesh v Ring hai lp B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 27 Tng t nh mng ring hai lp mng mesh v mang ring hai lp to kt ni gia mang ni b vicc mang ni b khc 1.7u nhc im ca h thng WDM a.u im : H thng WDM c dung lng truyn dn ln hn nhiu so vi h thng TDM. KhnggingnhTDMphitngtcsliukhilulngtruyndntng, WDM ch cn mang vi tn hiu, mi tn hiu ng vi mi bc sng ring (knh quang)WDMchophptngdunglngcamnghincmkhngcnphilpt thm si quangb.Nhc im : Dunglnghthngcnnh,chakhaithctritbngtnrnglncasi quang. Chi ph cho khai thc, bo dng tng do c nhiu h thng cng hot ng1.8B khuch i quang EDFA 1.8.1 Cc cu trc EDFA Hnh 1.20: Cu trc tng qut ca mt b khuch i EDFA B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 28 Cu trc ca mt b khuch i quang si pha trn Erbium EDFA (Erbium-Doped FiberAmplifier) c minh ha trn hnh 2.9. Trong bao gm: Si quang pha ion t him Erbium EDF (Erbium-Doped Fiber): l ni xy ra qutrnh khuch i (vng tch cc) ca EDFA. Hnh 1.21: Mt ct ngang ca mt loi si quang pha ion Erbium Trong,vnglitrungtm(cngknht3-6m)caEDFcphatrn ionEr3+lniccngsngbmvtnhiucaonht.VicphaccionEr3+ trongvngnycungcpschnglpcannglngbmvtnhiuviccion erbiumlnnhtdnnskhuchitthn.Lpbc(cladding)cchitsutthp hnbaoquanhvngli.Lpph(coating)bovbaoquanhsiquangtobnknh siquang tng cng l 250 m. Lp ph ny c chit sut ln hn so vi lp bc dng loi b bt k nh sng khng mong mun no lan truyn trong si quang. Nukhng k n cht pha erbium, cu trc EDF ging nh si n mode chun trongvin thng. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 29 1.8.2 L thuyt khuch i trong EDFA a) Gin phn b nng lung ca Er3+: Hnh 1.22: Gin phn b nng lng ca ion Er3+ trong si silica Gin phn b nng lng ca Er3+ trong si silica c minh ha trong hnh trn. Theo, cc ion Er3+ c th tn ti nhiu vng nng lng khc nhau c k hiu: 4I15/2 , 4I13/2 , 4I11/2,4I9/2, 4F9/2, 4S9/2, 2H11/2. Trong : - Vng4I15/2 c mc nng lng thp nht, c gi l vng nn (ground-state band) - Vng 4I13/2 c gi l vng gi bn (mestable band) v cc ion Er3+c thi gian sng(lifetime) ti vng ny lu (khong 10ms) trc khi chuyn xung vng nn. Thigian sng ny thay i ty theo loi tp cht c pha trong li ca EDF. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 30 - Vng 4I11/2, 4I9/2, 4F9/2, 4S9/2, 2H11/2 l cc vng nng lng cao, c gi l vng kchthch hay vng bm (pumping band). Thi gian cc ion Er3+ c trng thi nnglng trong cc vng ny rt ngn (khong 1 s) Ph hp th (absortion spectrum)v ph li (gain spectrum) ca EDFA c li pha Ge c biu din trn hnh 2.12 [2]. Hnh 1.23: Ph hp th (absorption spectrum) v ph li (gain spectrum) ca EDFAc li pha Ge [2]. b) Nguyn l hot ng ca EDFA Nguyn l khuch i ca EDFA c da trn hin tng pht x kch thch. Qu trnh khuch i tn hiu quang trong EDFA c th c thc hin: Khi s dng ngun bm laser 980nm, cc ion Er3+ vng nn s hp th nng lng tcc photon (c nng lng Ephoton =1.27eV) v chuyn ln trng thi nng lng cao hn vng bm (pumping band) (1). Ti vng bm, cc ion Er3+ phn r khng bc x rt nhanh (khong 1s) v chuynxung vng gi bn (2). Khi s dng ngun bm laser 1480nm, cc ion Er3+ vng nn s hp th nng lng tcc photon (c nng lng Ephoton =0.841eV) v chuyn sang trng thi nng lng cao hn nh ca vng gi bn (3) B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 31 Hnh 1.24: Qu trnh khuch i tn hiu xy ra EDFA vi hai bc sng bm 980 nmv 1480nm [1]. Cc ion Er3+ trong vng gi bn lun c khuynh hng chuyn xung vng nng lngthp (vng c mt in t cao) (4) Sau khong thi gian sng (khong 10ms), nu khng c kch thch bi cc photon cnng lng thch hp (pht x kch thch) cc ion Er3+ s chuyn sang trng thi nng lng thphn vng nn v pht x ra photon (pht x t pht) (5). 1.8.3 Yu cu i vi ngun bm a) Bc sng bm Vi cc vng nng lng c nu trong phn 1.8.2.a, nh sng bm c th c s dngti cc bc sng khc nhau 650 nm (4F9/2), 800 nm (4I9/2 ), 980 nm (4I11/2), 1480 nm (4I13/2). Tuynhin, khi bc sng bm cng ngn th cc ion Er3+ phi tri qua nhiu giai on chuyn inng lng trc khi tr v vng nn v pht x ra photon nh sng.Trong EDFA, iu kin c khuch i tn hiu l t c s nghch o nng bngcch s dng ngun bm bm cc ion erbium ln trng thi kch thch. C hai cch thc hinqu trnh ny: bm trc tip ti bc sng 1480 nm hoc bm gin tip bc sng 980 nm. Hin nay, bm bc sng 1480 nm c s dng rng ri hn v chng sn c hn v tin cy cao hn. tin cy l c im quan trng i vi laser bm v n dng bm chokhong cch di v trnh lm nhiu tn hiu.B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 32 Bng 2.1: So snh hai bc sng bm 980nm v 1480nm b) Cng sut bm Cng sut bm cng ln th s c nhiu ion erbium b kch thch trao i nng lngvi tn hiu cn khuch i v s lm cho h s khuch i tng ln. Tuy nhin, h s khuch ikhng th tng mi theo cng sut bm v s lng cc ion erbium c cy vo si l c gii hn. Ngoi ra, khi cng sut bm tng ln th h s nhiu s gim. iu ny s c trnh bytrong phn tnh h s nhiu ca EDFA. c) Hng bm B khuch i EDFA c th c bm theo ba cch: Bm thun (codirectional pumping): ngun bm c bm cng chiu vi hng truyntn hiu. Bm ngc (counterdirectional pumping): ngun bm c bm ngc chiu vi hngtruyn tn hiu. Bm hai chiu (dual pumping): s dng hai ngun bm v c theo hai chiu ngcnhau . Mt EDFA c bm bng mt ngun bm c th cung cp cng sut u ra cc ikhong +16 dBm trong vng bo ho hoc h s nhiu t 5-6 dB trong vng tn hiu nh. C hai bc sng bm c s dng ng thi c th cung cp cng sut u ra cao hn; mt EDFA c bm kp c th cung cp cng sut ra ti +26 dBm trong vng cng sut bm cao nht cth t c. Hnh di y th hin mt EDFA c bm kp. Gi tr cc c tnh ca b khuch i EDFA c trnh by trong bng 2.2 Bc sng bm980 nm1480 nm Tnh cht: li li cng sut bm Suy hao cng sut bm H s nhiu Cao hn Thp hn Cao hn Thp hn Thp hn Cao hn Thp hn Cao hn ng dngTin khuch iKhuch i cng sut B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 33 Hnh 1.25: Cu hnh b khuch i EDFA c bm kp [11]. 1.8.4Ph khuch i Ph li ca EDFA c trnh by trong hnh 2.12 l tnh cht quan trng nht caEDFA khi xc nh cc knh tn hiu c khuch i trong h thng WDM. Hnh dng ca phkhuch i ph thuc vo bn cht ca si quang, loi tp cht (Ge, Al) v nng tp cht c pha trong li ca si quang. Mt s bin php c s dng khc phc s khng bng phng ca ph li: Cng ngh cn bng li: dng b cn bng (equalizer) hp th bt cng sut bc sng c li ln v b khuch i tng cng sut ca bc sng c li nh. Thay i thnh phn trn trong si quang: dng si quang trn thm nhm, photphonhm hay flo cng vi erbium s to nn b khuch i c bng tn c m rng vph khuch i bng phng hn. B khuch i EDFA hot ng bng C (1530-1565 nm). Tuy nhin, li ca si pha tp c ui tri rng n khong 1605 nm. iu ny kch thch s pht trin ca cc h thng hot ng bng L t 1565 n 1625 nm. Nguyn l hot ng ca EDFA bng L ging nh EDFA bng C. Tuy nhin, c s khc nhau trong vic thit k EDFA cho bng C v bng L. Cc phn t bn trong b khuch i quang nh b cch ly (isolator) v b ghp (coupler) phthuc vo bc sng nn chng s khc nhau trong bng C v bng L. S so snh cc tnh chtca EDFA trong bng C v bng L c th hin trong bng 2.2. Bng 2.2: Bng so snh EDFA hot ng trong bng C v bng L Tnh chtBng CBng L li Ph li Nhiu ASE Cao hn t bng phng hn Thp hn Nh hn khong 3 ln Bng phng hn Cao hn B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 34 Hnh 1.25 trnh by cu trc ca mt b khuch i bng L lm bng phng li trongkhong bc sng 1570nm 1610nm vi thit k hai tng [3]. Tng u tin c bm bcsng 980nm v hot ng nh mt b EDFA truyn thng (si quang di 20-30nm) c kh nngcung cp li trong khong bc sng 1530-1570 nm. Ngc li, tng th hai c si quang di 200m v c bm hai chiu s dng laser 1480nm. Mt b isolator c t gia hai tng nycho php nhiu ASE truyn t tng th 1 sang tng th 2 nhng ngn ASE truyn ngc v tng th nht. Vi cu trc ni tip nh vy, khuch i hai tng c th cung cp li phng trn mtvng bng thng rng trong khi vn duy tr mc nhiu thp. Hnh 1.26 Cu hnh ca mt b khuch bng L lm bng phng li trong khong bcsng 1570nm 1610nm vi thit k hai tng. 1.8.5. Cc tnh cht ca EDFA a) li (Gain) li ca mt b EDFA c th c tnh theo phng trnh sau: G = exp[
(2.11) Trong : -
(z),
(z): mt ion erbium trng thi kch thch v trng thi nn ti v tr ztrong on si quang pha erbium. - L: chiu di si pha erbium. - (e)s , (a)s : tit din ngang hp th v pht x ca ion erbium ti bc sng tn hiu. Phng trnh (2.11) cho thy li lin quan n s nghch o nng trung bnh. Gi1 N, 2 N ln lt l nng ion Erbium mc nng lng nn v mc nng lng kch thchtrung bnh. Khi 1 N , 2 N s c tnh theo cng thc sau: B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 35 =
(2.12) =
(2.13) Phng trnh (2.11) c th c vit li mt cch n gin hn nh sau: G = exp[
(2.14)Trong phng trnh(2.12), (2.13) c hai tham s N1(z) v N2(z) l hm theo v tr z dc theo si quang c cho bi: (2.15) Trong : : thi gian sng ca ion erbium trng thi kch thch 4I13/2. Ps(z): cng sut ca tn hiu ti v tr z trong si quang. Pp(z): cng sut bm ti v tr z trong si quang. s : h s chng lp ti bc sng tn hiu. p : h s chng lp ti bc sng bm. A : din tch tit din ngang hiu dng. fs : tn s tn hiu. fp : tn s bm. N : mt ion erbium tng cng. s : l tit din ngang hp th v pht x ti bc sng tn hiu. p : l tit din ngang hp th v pht x ti bc sng bm. h : hng s Planck; h = 6,625.10-34J.s. T cng thc (2.15) ta thy h s khuch i ca EDFA ph thuc vo cc yu t sau: Ph thuc vo nng ion Er+3: Khi nng Er+3 trong si quang ca b EDFA tng th kh nng chng c chuyn ln mc nng lng cao hn cng nhiu, do h s khuch i tng. Nhng nu nng Er+3 tng qu cao s gy tch t dn n hin tng tiu hao quang lm cho h s khuch i gim. b) Cng sut ra bo ho (Output saturation power)
B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 36 S bo ho xy ra khi cng sut tn hiu vo EDFA ln gy ra s gim h s khuch i. S bo ho h s khuch i ny xut hin khi cng sut tn hiu tng cao v gy ra s pht x kch thch mt t l cao v do lm gim snghch o nng . iu c ngha l s cc ion erbium trng thi kch thch gim mt cch ng k. H qu l, cng sut tn hiu ng ra b hn ch bi s bo ho cng sut. Cng sut ra bo ha Pout, c nh ngha l tn hiu ra m h s khuch i b gim i 3 dB so vi khikhuch i tn hiu nh. Hnh 1.27: th biu din cng sut ra bo ho. Cng sut ra bo ha tng tuyn tnh theo cng sut bm vo ti bc sng bm 975 nm i vi bc sng tn hiu l 1555 nm v 1532 nm. 1.8.6. Nhiu trong b khuch i Nhiu trong b khuch i l mt yu t gii hn quan trng i vi h thng truyn dn.i vi EDFA, nh hng ca nhiu ASE c tnh thng qua thng s h s nhiu NF c chobi cng thc [2]: NF = 2nsp (2.17) Trong , nsp = N2/(N2-N1) c gi l h s pht x t pht, N1, N2 l nng ion Erbium mcnng lng nn v mc nng lng kch thch. Nh trnh by trong cng thc (2.15) v (2.16), N1, N2 thay i dc theo chiu di casiquangvphthucvocngsutcangunbmvcngsutcatnhiu.Do , h snhiu NF ca EDFA cng ph thuc vo chiu di ca si quang L v cng sut bm PP, gingnh li tn hiu ca EDFA. Hnh2.17biudinsthayicaNFvlitnhiutheochiudicasi quangvimtsgitrcaPP/Psatkhicngsuttnhiungvo1mWtibcsng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 37 1,53 m. Kt qu chothy rng FN c th t gn bng 3dB khi cng sut ca ngun bm PP>>Pp,sat.Vimcnhiutngithp,EDFAlslachnltngchocch thng thng tinquang WDM hin nay. D vy, nhiu do b khuch i cng lm gii hn cht lng cc h thngthngtin quang ng dis dng nhiu b khuch i EDFA. Vn nhiu tr nn nghimtrng khi h thng hot ng trong vng tn sc khng ca si quang. Khi cc hiu ng phituyn s lm tng nhiu b khuch i v gim ph tn hiu. Ngoi ra, nhiu ca b khuch icng gy nn rung pha nh thi. Vn ny s c trnh phn sau. Hnh 1.28 (a) H s nhiu FN v (b) li ca EDFA Khng ch gii hn t l SNR trong cc h thng s dng cc b khuch i quang, nhiu ASE m cn t ra nhng gii hn khc ln cc ng dng khc nhau ca cc b khuch i quang trong cc tuyn thng tin si quang. Chng hn, xem xt mt vi b khuch i quang c ghp tng dc theo mt khong truyn dn nh cc b lp tuyn tnh b suy hao si quang. Cng sut nhiu ASE Pnoise s l mt phn trong cng sut u ra Pout ca mt b khuch i no trong chui khuch i v tr thnh u vo ca b khuch i tip theo. Do s bo ho li ph thuc vo tng cng sut u vo, nhiu ASE t u ra ca cc tng trc trong chui khuch i c th ln n mc n s lm bo ho cc b khuch i pha sau. Nu s phn x ti u ra v u vo ca b khuch i thp, ASE c pht x theo hng ngc v u vo t cc b khuch i thuc cc tng sau cng c th vo cc b khuch i pha trc, cng lm tng s bo ho gy ra do ASE. Thm vo s suy gim hot ng v mt cng sut, s ln tp v pha ca tn hiu do pht x t pht cng gy nh hng nh nhiu tn s v nhiu bin , c bit l nhiu pha do s phn x ti cc giao din quang. V tn hiu n b khuch i quang cng c mt lng nhiu pha do s tri rng ph ca ngun laser cng lm tng cao nhiu trong b khuch i. iu ny s lm suy gim hot ng ca cc h thng thng tin quang. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 38 1.8.7 u khuyt im ca EDFA a) u im: - Ngun laser bm bn dn c tin cy cao, gn v cng sut cao. - Cu hnh n gin: h gi thnh ca h thng. - Cu trc nh gn: c th lp t nhiu EDFA trong cng mt trm, d vn chuyn vthay th. - Cng sut ngun nui nh: thun li khi p dng cho cc tuyn thng tin quang vtbin. - Khng c nhiu xuyn knh khi khuch i cc tn hiu WDM nh b khuch i quangbn dn. - Hu nh khng ph thuc vo phn cc ca tn hiu. b) nhc im: - Ph li ca EDFA khng bng phng. - Bng tn hin nay b gii hn trong bng C v bng L. - Nhiu c tch ly qua nhiu chng khuch i gy hn ch c ly truyn dn. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 39 CHNG II M PHNG TUYN THNG TIN QUANG WDM BNG PHN MM OPTISYSTEM 2.1. Tng quan v phn mm Optisystem Cng vi s bng n v nhu cu thng tin, cc h thng thng tin quang ngy cng tr nn phc tp. phn tich, thit k cc h thng ny bt buc phi s dng cc cng c m phngOptiSystem l phn mm m phng h thng thng tin quang. Phn mm ny c kh nng thit k, o kim tra v thc hin ti u ha rt nhiu loi tuyn thng tin quang, da trn kh nng m hnh ha cc h thng thng tin quang trong thc t. Bn cnh , phn mm ny cng c th d dng m rng do ngi s dng c th a thm cc phn t t nh ngha vo. Phn mm c giao din thn thin, kh nng hin th trc quan. OptiSystem cthgimthiu cc yu cu thigianvgimchiph linquann thit k ca cc h thng quang hc, lin kt, v cc thnh phn. Phn mm OptiSystem l mt sng to, pht trin nhanh chng,cng c thit k hu hiu cho php ngi dng lp k hoch, kimtra, v m phng gn nh tt ccc loi lin kt quang hc trong lp truyn dn camtquangphrngcaccmng quang hc tmngLAN,SAN,MAN ti mngultra-long-haul.Ncungcp lptruyndn,thitkv quy hoch hthng thng tinquangtccthnhphntimchthng.Hinhp canvi ccsnphm Optiwavekhcvcccngc thit k ca ngnhcngnghip inthnguphn mm thitk tnggpphnvoOptiSystem ynhanhtin snphm rath trng v rt ngn thi gian hon vn. 2.1.1. Li ch - Cung cp ci nhn ton cu vo hiu nng h thng - nh gi s nhy cm tham s gip vic thit k chi tit k thut- Trc quan trnh by cc ty chn thit k v d n khch hng tim nng- Cung cp truy cp n gin tp hp rng ri cc h thng c tnh d liu- Cung cp cc tham s t ng qut v ti u haB mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 40 - Tch hp vi h cc sn phm Optiwave 2.1.2. ng dng Tora pngnhucu caccnhkhoahc nghin cu,ks vinthng quang hc, tchhp hthng, sinhvinv mt lotcc ngidngkhc,OptiSystem png ccnhu cu cathtrng lngtnhsng phttrin mnhmnhngvnd sdng cng c thit k h thng quang hc. OptiSystem cho php ngi dng lp k hoch, kim tra, v m phng:- Thit k mng WDM / TDM hoc CATV- Thit k mng vng SONET / SDH- Thit k b pht, knh, b khuch i, v b thu thit k bn phn tn - nh gi BER v penalty ca h thng vi cc m hnh b thu khc nhau- Tnh ton BER v qu cng sut tuyn ca cc h thng c sng dng khuch i quang. - Thayihthngthams BER vtnhton khnng lin ktKhi hthng quang hc tr nn nhiu hn v phctphn,cc nh khoa hc vks ngy cng phip dngccphnmmkthutmphngtintin,quantrnghtrchovicthitk. Ngun OptiSystemvlinhhot toiukinthunli hiuquv hiuqu trongvic thit k ngun sng. " 2.2. c im v chc nng 2.2.1. Cu to th vin (Component Library) Th vin OptiSytem bao gm hng trm cc thnh phn cho php bn c th nhp cc thng s c o t cc thit b thc s. N tch hp vi cc th nghim v thit b o lng t cc nh cung cp khc nhau. Ngi s dng c th kt hp cc thnh phn mi da trn h thng con v ngi s dng v nh ngha l th vin, hoc s dng m phng cng vi mt cng c ca bn th ba chng hn nh MATLAB hoc SPICE. C th bao gm: -Th vin ngun quang -Th vin cc b thu quang -Th vin si quang -Th vin cc b khuch i (quang, in) B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 41 -Th vin cc b MUX, DEMUX -Th vin cc b lc (quang, in) -Th vin cc phn t FSO -Th vin cc phn t truy nhp -Th vin cc phn t th ng (quang, in) -Th vin cc phn t x l tn hiu (quang, in) -Th vin cc phn t mng quang -Th vin cc thit b o quang, o in 2.2.2. Tch hp vi cc cng c phn mm Optiwave Optisystemchophpngidngsdngkthpvicccngcphnmmkhc ca Optiwave nh OptiAmplifier, OptiBPM, OptiGrating, WDM_Phasar v OptiFiber thit k mc phn t. Miu t c tn hiu pha trn OptiSystem x l cc nh dng tn hiu hn hp cho tn hiu quang v introng Hp phn Th vin. OptiSystem tnh ton cc tn hiu ang s dngthch hp cc thut ton c lin quan n cc yu cu m phng chnh xc v hiu qu. Cht lng v thc hin cc thut ton d on hiu sut h thng, OptiSystem tnh ton cc thng s chng hn nh BER v Q-Factorbng cch s dngphntchshoc bn phntch kthutcah thng gii hn bi biu tng nhiu v ting n. Cc cng c trc quan nng caoCc cng c trc quan tin tin to ra ph OSA ,xung tn hiu,biu mt,phn cc trng thi,ccshpthnhvnhiuhnna.Ngoira,baogmcccngcnghincu WDM cc danh sch tn hiu ngun,hnh nh ting n v OSNR cho mi knh. Theo di, gim st d liu Bncthchn cc cng thnhphn lu dliuvgn mnhnh sau khi mphngkt thc. iu ny cho php bn x l d liu sau khi m phng m khng cn tnh ton li , Bn c th ty nh km mt shin hnh ti mn hnh ti cng mt cng.B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 42 2.2.3. Cc cng c hin th Optisystem c y cc thit b o quang, o in. Cho php hin th tham s, dng, cht lng tn hiu ti mi im trn h thng. Thit b o quang: -Phn tch ph (Spectrum Analyzer) -Thit b o cng sut (Optical Power Meter) -Thit b o min thi gian quang (Optical Time Domain Visualizer) -Thit b phn tch WDM (WDM Analyzer) -Thit b phn tch phn cc (Polarization Analyzer) -Thit b o phn cc (Polarization Meter)... Thit b o in: -Oscilloscope -Thit b phn tch ph RF (RF Spectrum Analyzer) -Thit b phn tch biu hnh mt (Eye Diagram Analyzer) -Thit b phn tch li bit (BER Analyzer) -Thit b o cng sut (Electrical Power Meter) -Thit b phn tch sng mang in (Electrical Carrier Analyzer)... 2.3. Tm tt hng dn s dng phn mm optisystem 2.3.1. Yu cu chung Trc khi ci t Optisystem, chc chn rng cc yu cu i vi h thng l ph hp vi cc m t di y. Yu cu phn cng v phn mm Optisystem yu cu cu hnh h thng thp nht l: -PC b vi x l pentium 3 hoc tng ng. -H iu hnh microsoft windows XP hoc Vista,32 hoc 64 bit. -400MB cng cn trng . - phn gii ha 1024x768,nh nht 65536 mu.B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 43 -Ram 128MB( gi ). -Internet explorer 5.5 hoc cao hn.-DirectX 8.1 hoc cao hn. Key bo v: Mt key bo v phn cng c cung cp km theo phn mm Ch : Xin hy chc rng key bo v phn cng khng c kt ni trong sut qu trnh ci t Optisystem. chc chn Optisystem vn hnh mt cch ng n, kim chng li theo cc bc sau: -Key bo v kt ni ng vo cng song song /USB ca my tnh. -Nu bn s dng nhiu hn mt key bo v, chc rng khng c s xung t gia key bo v Optisystem v cc key kia. Ch:Dngmthpchuyningnchnsxungtkeybov.Chcrng cp gia hp chuyn i v my tnh l ln nht ca dng c o. Th mc Optisystem Thng thng, b ci Optisystem s to ra mt th mc Optisystem trong cng ca bn. Th mc Optisystem gm mt s th mc con sau: -\bin cc tp thc thi c,th vin ng dn ng, v tp tr gip. -\components tham s cc phn t ca Optisystem t nh cung cp. -\doc ti liu h tr Optisystem. -\libraries th vin phn t Optisystem. -\samples tp v d Optisystem. -\toolbox tp lin h MATLAB. Ci t Optisystem c th c ci t trn Windows XP hoc Vista. Nn thot ht cc chng trnh Windows trc khi ci t chng trnh. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 44 Bng 1: Cc bc ci t BcThc hin 1 ngnhpvovivaitrngiquntrhocng nhp vo ti khon vi c quyn qun tr. 2Cho CD Optisystem vo CD ROM. 3 Trn thanh cng c,vo Start v chn Run. Hp thoi Run hin ra. 4 Trong hp thoi Run, g F:\setup.exe, F y l CD ROM ca bn. 5 Bm OK v theo cchng dnv du nhc trnmn hnh 6Khi ci t xong, khi ng li my tnh. Trnh din Optisystem bao gm nhiu nht l 15 kch bn. Vi cng mt tp trnh din nh nhau bn c th c nhiu kch bn vi cc phn t khc nhau v ty chn cc phn t. Khu qut Mi kch bn c th c cc tham s c gn sn trong ch qut. Bn c th t gn s ln qut bng cch thay i tham s la chn. Gi tr tham s thay i theo mi ln qut lp; to ln mt lot cc kt qu tnh ton khc nhau cn c trn s thay i gi tr tham s. Qut tham s ph thuc vo yu t ca mt kch bn: tham s v kt qu. Ti u ha Mikchbncstiuha.Sdngtiuhathayigitrcacc tham s bit trong sut qu trnh tnh ton v vy h thng ca bn cn t c nhiu iu kin yu cu. Qu trnh ti u ha l c lp vi cc ln qut tham s, nhng c th c s dng cho mi ln qut lp tham s ring bit. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 45 Hnh 2.1: Thnh phn trnh din 2.3.2 Hng dn s dng phn mm optisystem Th vin cc phn t ( component library ) : Ngi dng truy cp vo ly cc phn t thit k (Hnh 1) Hnh 2.2: Th vin cc phn t B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 46 Th vin cc phn t: - Th vin ngun quang - ( optical sources library ) - Th vin cc b thu quang - (receivers library) - Th vin si quang - (optical fiber library) - Th vin cc b khuch i (quang, in) - (amplifier library) - Th vin cc b MUX, DEMUX - Th vin cc b lc (quang, in) - (filter library) - Th vin cc phn t FSO - ( free space optics library) - Th vin cc phn t truy nhp - ( access library) - Th vin cc phn t th ng (quang, in) - (passiver library) - Th vin cc phn t x l tn hiu (quang, in) -( signal processing library) - Th vin cc phn t mng quang (network library) - Th vin cc thit b o quang, o in Ngoi ra cc phn t c nh ngha sn, Optisystem cn c - Cc phn t Measured components. Vi cc phn t ny, Optisystem cho php nhp cctham s c o t cc thit b thc ca cc nh cung cp khc nhau. - Cc phn t do ngi s dng t nh ngha ( User-defined Components) B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 47 Hnh 2.3: Giao din th vin Giao din ngi s dng ( GUI ) - Project layout : phn m ngi s dng thit k Hnh 2.4. Giao din ngi s dng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 48 - Dockers : bao gm + Project Browser : truy nhp n cc tham s v kt qu ca thit k (Hnh 3) Hnh 2.5: Project Browser + Description : a ra cc thng tin m t tm tt v thit k Hnh 2.6: Description B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 49 + Status bar : hin th nhng gi v vic s dng Optisystem Hnh 2.7: Status bar + Menu bar : cha cc menu c sn trong Optisystem Hnh 2.8: Menu bar + Pan window Hnh 2.9: Pan window + Tool bars : cc thanh cng c c sn trn ca s B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 50 Hnh 2.10: Tool bars 2.3.3 To mt d n mi - Vo File menu, la chn New, ca s Project layout xut hin Hnh2.11. Ca s Project layout B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 51 -VoComponentLibrary,dngchutkophntcnsdngvthvoMain Layout (Hnh 10) Hnh 2.12. t phn t vo Main layout - Vic kt ni gia cc phn t trong thit k c th c thc hin mt cch t ng hoc bng tay nh vic s dng cc nt chc nng trong Layout Operations Hnh 2.13: Kch hot kt ni t ng Hnh 2.14:Hy b ch kt ni t ng B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 52 2.3.4. Hin th v thay i tham s ca cc phn t trong d n Khi to mt thit k mi trn Optisystem, phi thit lp cc tham s ton cc. Cc tham s ny s lin quan n tc , chnh xc v yu cu v b nh cho vic thc hin m phng thit k. Cc tham s ny c gi l tham s ton cc v n nh hng n tt c cc thnh phn trong thit k c s dng cc tham s ny. Trong Optisystem, cc tham s ny bao gm: - Tc bit (bit rate) - Chiu di chui bit (Bit sequence length) - S mu trn mt bit (Number of samples per bit). thit lp thng s ton cc ta thc hin nh sau: -Cch 1: Kch p vo mn hnh Layout. -Cch2:Layout->ParameterstcngcMenu.KhimnhnhParameters xut hin: Hnh2.15 :mn hnh Parameters B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 53 * Thay i cc tham s ca cc phn t trong bi ton m phng: - Thc hin kch p vo phn t cn thay i tham s hp thoi v cc tham s ca phn t xut hin . - Di chuyn con tr n cc gi tr thch hp. - Nhp gi tr tham s mong mun. Ch : C ba ch ca tham s l Norman, Script v Sweep: - Trong ch Scrip c thc hin khi tham s ny l tham s ton cc, n c lin quan n tt c cc phn t khc trong h thng. - Ch Sweep c s dng khi thchin qut tham s. - Ti mc Power cho php ta nhp cng sut pht quang c gi tr ph hp vi tng knh.Tip theo tin hnh thay i tc bit (Bit rate): Ti mc value chn Set bit rate. Hnh 2.16 :Chn trng thay i tc bt B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 54 Tin hnh nhp tc bit 10Gbit/s= 10000000000 (bt/s). Hnh 2.17 : Nhptc bt mun thay i B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 55 + Tin hnh thit lp ca s thi gian: ti Value chn Set Time Window v nhp gi tr Hnh2.18 : Thit lp ca s thi gian thc B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 56 Hnh 2.19 : Thay i cng sut pht quang B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 57 + Kt thc ci t tham s ton cc bng cch click OK cc thng s ton cc c hin th nh sau: * Xa cc tham s mi khi d n: thc hin qua cc bc: - Trong hp thoi Layout Parameter, kch vo ct Value bn cnh tham s bn mun thay i. - Kch Remove Par: Tham s c xa. Ch : Bn khng th chnh sa hoc xa cc tham s h thng. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 58 2.3.5. Chy m phng a.Chy m phng n t hp (Ctrl F5), hoc click Colculatol trn thanh cng c. Mn hnh hin th: Hnh 2.20: Giao din mn hnhchy m phng+ Tip theo click vo nt Run chy chng trnh: B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 59 Hnh 2.21 : Chychng trnh + Sau khi chng trnh chy xong, hin th gi tr ca BER ta kch p vo thit b o BER ca knh u tin (CH1).B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 60 Hnh 2.22: o t s BER ca knh+ Thc hin tng t nh vy vi cc knh cn li tm cc gii gi tr ph hp. b. Hin th kt qu m phng - Kch p chut vo cc phn t hin th trong thit k hin th th v cc kt qu m qu trnh m phng to ra. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 61 Hnh 2.23 : Kt qu m phngc. tin hnh thit lp tham s qutta thc hin nh sau:+ Cch 1: n t hp phm Ctrl +Home + Cch 2: Thc hin 3 bc sau: Bc 1: Kch chut vo nt Set Total Sweep Iterarion trn Layout Bar hp thoi Total Parameter Sweep Iterationstrn Layout Tool Bar xut hin trn hnh: Bc 2: Nhp gi tr s ln qut . Bc 3: Click chut OK B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 62 Hnh 2.24: Thit lp tham s quyt d. Thay i s ln qut:Sau khi tnh ton, thay i s ln qut hin th trn bn thit k (layout), thc hin cc bc sau: - Bc 1: La chn Layout > Set Current Sweep Interation trn Menu toolbar. Hp thoi Set Current Sweep Iterarion xut hin nh trn hnh 20 - Bc 2: Nhp vo s ln qut mun hin th trn bn thit k - Bc 3: Kch chut vo nt OK HocsdngPreviousSweepInterarionhocNextInterationtrnLayout Toolbal chuyn i s ln qut. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 63 Hnh2.25: Chuyn i s ln qut. e.Thayigitrthamsqut:Saukhichnslnqutthchngtathc hinnhpgitrcnqutcathams.Trckhinhpthamscnqutphichuyn sang ch qut Sweep Mode. f. chuyn sang ch qut cho tham s thc hin nh sau: + La chn Layout -> Parameter Sweep trn Menu Toolbar . Hp thoi v cc tham s ca cc phn t nh hnh v. Ch yu thit lp qut tham s cho ngun lazer. + Kch p vo ngun CW lazer Properieshp thoi xut hin: B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 64 Hnh 2.26: Hp thoi chuyn sang ch qut cho tham s+ Ti Mode kch chut chn Sweep. Kt thc bng OK. Hnh2.27: Chn ch ca tham s + Sau tin hnh in tham s qut bng cch click chut vo Parameter Sweep trong ct Value. Kt thc bng OK. + Sau khi thay i xong cc tham s qut tin hnh bc tip theo. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 65 g. Hin th kt qu m qu m phng quttham s Sau khi chng trnh chy xong, hin th gi tr ca BER ta kch p vo thit b o BER ca knh u tin (CH1). hin th kt qu m phng qut tham s (i vi thit k h thng, thng hin th s thay i BER theo gi tr ca tham s qut), thc hin cc bc sau: oBc 1: La chn Report tab trong ca s Project Layout oBc 2: Kch chut vo nt Opti2Dgraph trn Report toolbar oBc3:TrongProjectBrowser,lachnthamsSweepMode, ko tham s ny v th vo trc X ca th 2D oBc 4: TrongProject Browser, la chn tham s Min.Log of BER ca thit b phn tch li bit, ko tham s ny v th vo trc Y ca th 2D Kt qu thay i BER theo tham s qut s hin th trn th 2D. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 66 Hnh 2.28:. Cc bc hin th kt qu m phng qut tham s 2.4. M hnh m phng 2.4.1 Yu cu thit k 1) Bi ton: Xy dng phng n thit k h thng thng tin quang WDM c s dng khuch i quang EDFA vi cc yu cu thit k nh sau: -Tc bit:10 Gbit/s -C ly truyn dn:300 km -S lng knh bc sng:4 knh Mt s gi khi thit k: -Loi si: Si quang n mode chun (G.652) B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 67 -Ngun pht:- Loi ngun: Laser.- Phng thc iu ch: iu ch ngoi -B thu: S dng PIN kt hp vi b lc thng thp Bessel 2) Yu cu:a) S dng phn mm Optisystem xy dng m hnh m phng h thng thng tin quang WDM theo phng n thit k. Lu : cc tham s ton cc (global parameters m phng) c thit lp nh sau -Tc bit:10 Gbit/s -Chiu di chui:128 bits -S mu trong 1 bit:64 b) a cc thit b o vo m hnh m phng. Cc thit b o trn tuyn c t ti cc v tr ph hp xc nh c cht lng v dng tn hiu ti cc im cn thit trn tuyn. Cc thit b o c bn: -Thit b o cng sut quang -Thit b phn tch ph quang -Thit b o BER c) Chy m phng d) Hin th kt qu m phng bng cc thit b o t trn tuyn e) Thay i cc tham s ca cc phn t trn tuyn t c BER = 10-12 3) Bo co kt qu thc hnh -M hnh m phng -Cc tham s m phng chi tit -Kt qu m phngoKt qu m phng theo phng n thit k ban u h thng ban u oS thay i ca cc tham s thit k t c BER = 10-12 -Nhn xt, phn tch kt qu m phng . B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 68 2.4.2 M phng theo phng n thit k 2.4.2.1 Tuyn pht quang: chn ca s truyn 1550nm EDFA bng C Mi knh quang bao gm ngun pht quang lazer CW lazer, b pht xung RZ pulse genarator, b pht bit in pseudom-Radom Bit sequence Genarator, b iu ch Mach-zehnder.Tuyn pht quang gm 4 knh quang c tch hp thng quang b ghp knh quang MUX. Thit lp tham s ton cc Tc bt:10GBps Chiu di chui: 128bits S mu trong mt bt: 64 S mu =Chiu di chuiS mu trong mt trong mt bit=12864=8192
Hnh 2.29: Thit lp tham s ton cc Ngun pht: S dng ngun CW Laser ( continous Wave Laser ): nhm gim nh hng ca tn sc si. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 69 Hnh 2.30: Ngun Laser pht CW Laser B to xung RZ Hnh 2.31: B to xung RZ B to chui bit Hnh 2.32. B to chui bt B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 70 B iu ch ngoi Hnh 2.33: B iu ch Mach-Zehnder B ghp knh quang (ghp 4 knh) Hnh 2.34:B ghp knh MUX 41 Ton tuyn pht 4 knh quang B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 71 Hnh 2.35: Tuyn pht quang 2.4.2.2 Tuyn truyn dn quang Hnh 2.36. Tuyn truyn dn quang B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 72 Si quang s dng G.652 c cc tham s: ti ca s truyn 1550nm th: -Suy hao si:0.2dB - tn sc:0.335 ps/nmkm - dc tn sc (0.092ps/nm^2/k): 0.075ps/nm^2/k. Do khong cch ng truyn ln thun tin cho vic m phng chng ta s dng b Sloop ng vai tr nh mt b nhn cc vng lp. Chn chiu di si G.652 l 60km, s b lp l: 300km60km=5 b. Hnh 2.37.B lp Do si quang c suy hao tn sc nn trong tuyn truyn dn s s dng b b tn sc DCF. Thng s ca b b tn sc: -Gi s si G652 c chiu di l L1=50km. - tn sc l : D1= 16.75 ps/nm.km. - dc tn sc : 0.075ps/nm^2.km. -Chiu di si b tn sc ( DCF) l L2=60km-50km=10km-Th b tn sc D2= -D1L1/L2.= -5016.75/10= -83 ps/nm.km. -dc tn sc : 0.375ps/nm^2.km. B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 73 Hnh 2.38. Thng s si b tn sc DCF Khuch i quang EDFA: Do suy hao si quang nn cn s dng b khuch i EDFA b suy hao si. + L1=50km th suy hao si l: 500.2=10dB li ca b khuch i EDFA l 10dB + L2=10km th suy hao si l: 100.2=5dB li ca b khuch i EDFA l 5dB B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 74 2.4.4.3 Tuyn thu ca h thng WDM Hnh 2.39. Tuyn thu WDM
Thit b o BER Hnh 2.40. Thit b o BER B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 75 2.4.3 Kt qu m phng theo yu cu thit k Tuyn WDM theo yu cu Hnh 2.41.Tuyn WDM thit k theo yu cu
B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 76 Quang ph tn hiu pht Hnh 2.42. Quang ph tn hiu pht Quang ph tn hiu thu B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 77 Hnh 2.43. Quang ph tn hiu u thu knh th 3 Cng sut tn hiu pht Hnh 2.44. Tng cng sut pht Cng sut tn hiu thu Hnh 2.45. Cng sut thu ca knh 4 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 78 T l li bit BER -Mt quang Hnh 2.46.Hin th mt quang -BER ca mt knh Hnh 2.47. BER ca knh th nht l 10-13 B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 79 2.4.4. Kt qu m phng thay i cc tham s t BER=10-12 Khi thay i mt trong cc tham s h thng th t s li bt BER se thay i theo. -Thay i cng sut Laser pht Hnh 2.48. Thay i cng sut Laser pht -Hoc thay i h s suy hao si quang ln thnh 0.2025dB Hnh 2.49. H s suy hao si quang thay i B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 80 BER thay i + BER ca knh th nht thay i Hnh 2.50. BER ca knh th nht t 10-12 +Mt quang: Hnh 2.51. BER t 10-12 khi thay i mt s tham s B mn Thng tin quang 2 Th.s Cao Hng Sn Thit k v m phng h thng thng tin quang Nhm 2 WDM s dng phn mm Optisystem 81 TI LIU THAM KHO -TS. V Vn San, H thng thng tin quang s dng k thut WDM, tp ch bu chnh vin thng s 9-1999 -Gio trnh K thut thng tin quang 2 (dng cho sinh vin h o to i hc t xa)_Ths. Vn Vit Em. -Kevin H. Liu, IP over WDM, John Wiley & Sons, Inc, 2002 -Ti liu:khuch i quang si v kh nng ng dng vo mng vin thng- Dng c Tu-H thng ghp knh theo bc sng quang - Hc vincng ngh bu chnh vin thng, NXB Bu in, H Ni 5-2001