Wavelength Division Multiplexing yog cov txheej txheem uas tso cai rau kev thauj mus los ntawm ntau zaus (lossis wavelengths) kom xa mus rau tib lub sijhawm sib txuas ntawm fiber ntau optical fiber ntau ib txhij. Qhov no yog ua tiav los ntawm kev siv cov khoom siv xws li optical transmitters lossis transceivers nrog cov zis tawm mus rau ib tus neeg thiab cov wavelengths tshwj xeeb kom muaj qhov sib txawv thiab tsis sib tshooj.
Coarse Wavelength Division Multiplexing (CWDM) siv wavelengths ntawm 1260nm thiab 1670nm (O, E, S, C, L thiab U kis tau tus mob bands) thiab tso cai mus txog 18 tus neeg raws li tsim nyob rau hauv cheeb tsam no, nqa ib qho kev sib txuas ntawm lub suab, cov ntaub ntawv. los yog yees duab nrog cov channel spaced 20nm sib nrug. CWDM yog ib qho kev daws teeb meem zoo rau kev xa tawm bandwidth tsawg. Txawm li cas los xij, vim tias CWDM cov teeb liab tsis tuaj yeem ua kom nrov, tsis muaj cov khoom siv kho qhov muag broadband muaj peev xwm txhawb nqa qhov ntau thiab qhov kev ncua deb yog txwv rau 80km.
Ib qhov Dense Wavelength Division Multiplexing (DWDM) kev daws teeb meem yuav siv WDM mus rau qib tom ntej los ntawm kev txo cov channel sib nrug mus rau 0.8nm lossis tsawg dua thiab txo qis kev ua haujlwm wavelength ntau. Qhov no tuaj yeem tsim tau 80 lossis ntau dua los yog txoj kab tsheb khiav, qhib lub qhov rooj rau ntau qhov kev kub ceev, kev siv bandwidth siab.
Amazingly, tag nrho DWDM wavelengths nyob hauv qhov nqaim 1525nm rau 1565nm cheeb tsam hu ua C-Band. Qhov chaw no yog siv vim qhov qis qis (0.25dB/km) teeb liab poob (fiber attenuation) piv rau qis wavelengths pom hauv O lossis E-bands, piv txwv li. Raws li qhov sib txawv ntawm qhov nqaim channel, cov lasers siab dua thiab cov txheej txheem lim dej yuav tsum tau ua kom muaj kev ncaj ncees ntawm cov channel thiab txo qhov cuam tshuam.
DWDM Architecture
Passive DWDM network architecture pib nrog lub transponder lossis transceiver txais cov ntaub ntawv nkag ntawm ntau hom tsheb thiab cov txheej txheem. Qhov no transponder ua lub luag haujlwm tseem ceeb ntawm kev qhia cov ntaub ntawv nkag mus rau ib tus neeg lub wavelengths. Txhua lub wavelength yog pub rau ib qho optical multiplexer (MUX) uas lim thiab sib txuas ntau lub teeb liab rau hauv ib qho chaw tso zis rau kev sib kis ntawm lub ntsiab / tub ntxhais / feem ntau DWDM fiber ntau. Thaum qhov kawg tau txais, cov wavelengths tuaj yeem raug cais tawm los ntawm kev sib cais ntawm tus kheej los ntawm kev siv lub tshuab optical demultiplexer (De-MUX). Txhua channel yog ces xa mus rau qhov tsim nyog cov neeg siv khoom-sab tso zis los ntawm ib qho ntxiv wavelength matched transponder.
Vim tias DWDM thev naus laus zis sib tshooj ntawm CWDM zaus band, cov tshuaj "hybrid" kuj tuaj yeem xaiv. Hom kab ke no tawm ntawm CWDM MUX thiab deMUX kho vajtse nyob rau hauv qhov chaw, ntxig DWDM wavelengths nyob rau sab saum toj ntawm cov channel uas twb muaj lawm hauv 1530 txog 1550nm ntau yam, tsim txog li 28 qhov ntxiv. Hom hybrid no tuaj yeem muab lub peev xwm loj ntxiv yam tsis tas yuav muaj kev txhim kho fiber ntau lossis cov lag luam wholesale kev hloov pauv rau lub tuam txhab.
Ib qho Optical Add Drop Multiplexer (OADM) yog ib qho kev xaiv ntawm DWDM architecture uas tuaj yeem muab ntxiv rau cov tes hauj lwm passive lossis kev ua haujlwm los pab txhawb qhov sib ntxiv lossis rho tawm ntawm qhov teev wavelength los ntawm qhov chaw nruab nrab ntawm qhov chaw nyob nruab nrab ntawm lub ntsiab / tub ntxhais / feem ntau DWDM fiber ntau . Bidirectional architecture suav nrog transmitters thiab receivers ntawm ob qhov kawg ntawm lub Circuit Court nrog rau kev sib xyaw ua ke MUX / De-MUX li.
Rau kev sib txuas ntev ntev, DWDM architecture nce qhov nyuaj nrog qhov sib ntxiv ntawm cov khoom siv hluav taws xob uas xav tau los them rau qhov kev poob qis uas yuav ua rau cov teeb liab txais thiab cov ntaub ntawv rov qab ua tsis tau. Ib qho Erbium Doped Fiber Amplifier (EDFA) tuaj yeem siv los ua lub zog txhawb lossis tso lub suab nrov los txhawb lub zog kho qhov muag ib yam li lawv tawm ntawm MUX, thaum lub suab nrov ua ntej ua haujlwm zoo ib yam ua ntej nkag mus rau DeMUX. Ntxiv inline amplifiers kuj yuav suav nrog. Passive networks, yam tsis muaj EDFA, txo qhov nyuaj no.
