Hauv EPON system, OLT txuas nrog ntau ONUs (optical network units) los ntawm POS (passive optical splitter).Raws li cov tub ntxhais ntawm EPON, OLT optical modules yuav cuam tshuam ncaj qha rau kev ua haujlwm ntawm tag nrho 10G EPON system.
1.Introduction to 10G EPON symmetrical OLT optical module
10G EPON symmetrical OLT optical module siv lub uplink tawg txais tos thiab downlink nruam kis hom, uas yog tsuas yog siv rau kho qhov muag / hluav taws xob hloov dua siab tshiab nyob rau hauv 10G EPON systems.
Qhov tau txais ib feem muaj TIA (transimpedance amplifier), APD (Avalanche Photodiode) ntawm 1270 / 1310nm, thiab ob lub LA (limiting amplifiers) ntawm 1.25 thiab 10.3125 Gbit / s tus nqi.
Kev xa tawm kawg yog tsim los ntawm 10G EML (electro-absorption modulation laser) thiab 1.25 Gbit / s DFB (distributed feedback laser), thiab nws cov emission wavelengths yog 1577 thiab 1490nm, feem.
Kev tsav tsheb muaj xws li digital APC (Automatic Optical Power Control) Circuit Court thiab TEC (Temperature Compensation) Circuit Court kom tswj tau qhov ruaj khov 10G laser emission wavelength.Kev sib kis thiab tau txais cov ntsuas ntsuas yog siv los ntawm ib qho nti microcomputer raws li SFF-8077iv4.5 raws tu qauv.
Vim tias qhov kawg tau txais ntawm OLT optical module siv kev txais tos tawg, lub sijhawm txais tos yog qhov tseem ceeb tshwj xeeb.Yog tias lub sijhawm txais tos ntev ntev, nws yuav ua rau muaj kev cuam tshuam loj heev, thiab tej zaum yuav ua rau kev txais tos tawg tsis ua haujlwm zoo.Raws li cov kev cai ntawm IEEE 802.3av raws tu qauv, lub sij hawm tsim ntawm 1.25Gbit / s burst txais yuav tsum <400 ns, thiab burst reception rhiab heev yuav tsum <-29.78 dBm nrog me ntsis yuam kev tus nqi ntawm 10-12;thiab 10.3125 Gbit / s Lub sijhawm txais tos tawg yuav tsum yog <800ns, thiab qhov kev txais tos tawg yuav tsum yog <-28.0 dBm nrog qhov yuam kev me ntsis ntawm 10-3.
2.10G EPON symmetrical OLT optical module tsim
2.1 Kev tsim qauv
10G EPON symmetrical OLT optical module yog tsim los ntawm triplexer (ib leeg-fiber peb-txoj kev module), xa, txais, thiab saib xyuas.Lub triplexer muaj xws li ob lub lasers thiab ib tug ntes.Lub teeb kis tau tus mob thiab lub teeb tau txais tau muab tso rau hauv cov khoom siv kho qhov muag los ntawm WDM (Wavelength Division Multiplexer) kom ua tiav ib leeg-fiber bidirectional kis tau tus mob.Nws cov qauv yog qhia hauv daim duab 1.
Cov kis tau tus mob muaj ob lub lasers, uas nws lub luag haujlwm tseem ceeb yog hloov 1G thiab 10G hluav taws xob teeb liab mus rau hauv cov teeb liab kho qhov muag, raws li, thiab ua kom lub zog kho qhov muag ruaj khov nyob rau hauv lub voj voog kaw los ntawm digital APC circuit.Nyob rau tib lub sijhawm, lub microcomputer ib-chip tswj qhov loj ntawm qhov kev hloov pauv tam sim no kom tau txais qhov kev ploj tuag qhov xav tau los ntawm lub kaw lus.Lub TEC Circuit Court yog ntxiv rau 10G transmitting circuit, uas zoo heev stabilizes cov zis wavelength ntawm 10G laser.Qhov tau txais ib feem siv APD los hloov cov teeb liab pom qhov muag pom rau hauv lub teeb liab hluav taws xob, thiab tso tawm nws tom qab amplification thiab shaping.Txhawm rau kom ntseeg tau tias qhov rhiab heev tuaj yeem ncav cuag qhov zoo tagnrho, nws yog ib qho tsim nyog los muab lub siab ruaj khov rau APD ntawm qhov sib txawv ntawm qhov kub thiab txias.Lub computer ib-chip ua tiav lub hom phiaj no los ntawm kev tswj hwm APD high-voltage circuit.
2.2 Kev siv ntawm ob-tus nqi tawg txais tos
Qhov tau txais ib feem ntawm 10G EPON symmetric OLT optical module siv txoj kev tau txais tawg.Nws yuav tsum tau txais cov cim tawg ntawm ob qhov sib txawv ntawm 1.25 thiab 10.3125 Gbit / s, uas yuav tsum tau txais ib feem kom muaj peev xwm paub qhov txawv ntawm qhov sib txawv ntawm ob tus nqi sib txawv kom tau txais cov khoom siv hluav taws xob ruaj khov.Ob lub tswv yim rau kev siv dual-tus nqi tawg txais tos ntawm OLT optical modules tau thov ntawm no.
Vim hais tias lub teeb liab input optical siv TDMA (Time Division Multiple Access) thev naus laus zis, tsuas yog ib tus nqi ntawm lub teeb tawg tuaj yeem muaj nyob rau tib lub sijhawm.Lub teeb liab input tuaj yeem sib cais hauv qhov chaw kho qhov muag los ntawm 1: 2 optical splitter, xws li Qhia hauv daim duab 2. Los yog siv tsuas yog lub ntsuas kub ceev los hloov 1G thiab 10G optical signals rau hauv cov hluav taws xob tsis muaj zog, thiab tom qab ntawd cais ob lub tshuab hluav taws xob. teeb liab nrog tus nqi sib txawv los ntawm qhov loj dua bandwidth TIA, raws li qhia hauv daim duab 3.
Thawj lub tswv yim qhia hauv daim duab 2 yuav coj qee qhov kev poob qis thaum lub teeb dhau los ntawm 1: 2 optical splitter, uas yuav tsum tau nthuav tawm cov teeb liab input optical, yog li lub optical amplifier tau nruab rau pem hauv ntej ntawm optical splitter.Cov teeb liab kho qhov muag sib cais yog tom qab ntawd raug hloov kho qhov muag / hluav taws xob los ntawm cov khoom siv hluav taws xob sib txawv, thiab thaum kawg ob hom hluav taws xob ruaj khov hluav taws xob tso tawm tau txais.Qhov loj tshaj qhov tsis zoo ntawm qhov kev daws teeb meem no yog siv lub tshuab hluav taws xob kho qhov muag thiab 1: 2 optical splitter, thiab ob lub cuab yeej xav tau los hloov cov teeb liab kho qhov muag, uas ua rau kom qhov nyuaj ntawm kev siv thiab nce tus nqi.
Nyob rau hauv lub tswvyim thib ob qhia nyob rau hauv FIG.3, lub tswv yim kho qhov muag teeb liab tsuas yog yuav tsum dhau los ntawm lub tshuab ntes thiab TIA kom ua tiav kev sib cais hauv hluav taws xob.Lub hauv paus ntawm qhov kev daws teeb meem no yog nyob rau hauv kev xaiv TIA, uas yuav tsum tau TIA kom muaj bandwidth ntawm 1 ~ 10Gbit / s, thiab tib lub sijhawm TIA muaj cov lus teb ceev ceev hauv qhov bandwidth no.Tsuas yog los ntawm qhov ntsuas tam sim no ntawm TIA tuaj yeem tau txais tus nqi teb sai, qhov kev txais tau zoo tuaj yeem lav tau zoo.Qhov kev daws teeb meem no zoo heev txo qhov nyuaj ntawm kev siv thiab khaws cov nqi tswj hwm.Hauv qhov tsim tiag tiag, peb feem ntau xaiv lub tswv yim thib ob kom ua tiav qhov kev txais tos thib ob.
2.3 Tsim cov khoom siv kho vajtse ntawm qhov kawg tau txais
Fig. 4 yog qhov kho vajtse Circuit Court ntawm qhov tawg tau txais.Thaum muaj qhov tawg tawm qhov muag tawm, APD hloov cov teeb liab kho qhov muag rau hauv lub teeb liab hluav taws xob tsis muaj zog thiab xa mus rau TIA.Lub teeb liab tau nthuav dav los ntawm TIA rau hauv 10G lossis 1G hluav taws xob teeb liab.Lub 10G hluav taws xob teeb liab yog nkag mus rau 10G LA los ntawm qhov zoo sib txuas ntawm TIA, thiab 1G hluav taws xob teeb liab yog tawm tswv yim rau 1G LA los ntawm kev sib txuas tsis zoo ntawm TIA.Capacitors C2 thiab C3 yog coupling capacitors siv los ua kom tiav 10G thiab 1G AC-coupled tso zis.Txoj kev AC-coupled raug xaiv vim nws yooj yim dua li DC-coupled txoj kev.
Txawm li cas los xij, AC coupling muaj tus nqi thiab tso tawm ntawm lub capacitor, thiab cov lus teb ceev rau lub teeb liab cuam tshuam los ntawm tus nqi thiab tawm lub sij hawm tas li, uas yog, lub teeb liab tsis tuaj yeem teb rau lub sijhawm.Cov yam ntxwv no yog ua txhua yam kom poob qee lub sijhawm txais tos, yog li nws yog ib qho tseem ceeb uas yuav tsum xaiv qhov loj npaum li cas AC coupling capacitor.Yog tias ib qho me me sib txuas capacitor raug xaiv, lub sij hawm daws teeb meem tuaj yeem ua luv luv, thiab cov teeb liab kis tau los ntawm ONU hauv txhua lub sijhawm qhov tuaj yeem tau txais tag nrho yam tsis muaj kev cuam tshuam rau kev txais tos vim tias lub sijhawm txais tos ntev dhau lawm thiab tuaj txog ntawm lub sijhawm tom ntej. qhov.
Txawm li cas los xij, me me capacitance yuav cuam tshuam rau kev sib txuas ua ke thiab txo qhov ruaj khov ntawm kev txais tos zoo heev.Loj dua capacitance tuaj yeem txo qhov system jitter thiab txhim kho qhov rhiab heev ntawm qhov kawg tau txais.Yog li ntawd, txhawm rau coj mus rau hauv tus account lub sijhawm txais tos daws teeb meem thiab txais tos rhiab heev, qhov tsim nyog coupling capacitors C2 thiab C3 yuav tsum tau xaiv.Tsis tas li ntawd, txhawm rau txhawm rau ua kom muaj kev ruaj ntseg ntawm cov teeb liab hluav taws xob tawm, lub coupling capacitor thiab qhov sib txuam resistor nrog qhov tsis kam ntawm 50Ω yog txuas nrog lub davhlau ya nyob twg tsis zoo ntawm LA.
LVPECL (Low Voltage Positive Emitter Coupling Logic) Circuit Court muaj li ntawm cov resistors R4 thiab R5 (R6 thiab R7) thiab 2.0 V DC voltage qhov chaw los ntawm qhov sib txawv teeb liab tso zis los ntawm 10G (1G) LA.hluav taws xob teeb liab.
2.4 Launch seem
Kev xa tawm ib feem ntawm 10G EPON symmetric OLT optical module feem ntau muab faib ua ob feem ntawm 1.25 thiab 10G kis, uas feem ntau xa cov teeb liab nrog lub wavelength ntawm 1490 thiab 1577 nm mus rau downlink.Noj 10G kis tau tus mob ua piv txwv, ib khub ntawm 10G qhov sib txawv ntawm cov teeb liab nkag mus rau CDR (Clock Shaping) nti, yog AC-coupled rau 10G tsav nti, thiab thaum kawg yog sib txawv input rau hauv 10G laser.Vim tias qhov kub thiab txias hloov yuav muaj kev cuam tshuam zoo rau lub laser emission wavelength, txhawm rau txhim kho lub wavelength mus rau qib uas yuav tsum tau ua los ntawm cov txheej txheem (tus txheej txheem xav tau 1575 ~ 1580nm), kev ua haujlwm tam sim no ntawm TEC Circuit Court yuav tsum tau kho, yog li tias cov zis wavelength tuaj yeem tswj tau zoo.
3. Cov txiaj ntsig thiab kev tshuaj xyuas
Qhov ntsuas ntsuas tseem ceeb ntawm 10G EPON symmetric OLT optical module suav nrog lub sijhawm teeb tsa lub txais, txais lub siab xav, thiab xa daim duab qhov muag.Cov kev ntsuam xyuas tshwj xeeb yog raws li hauv qab no:
(1) Tau txais lub sijhawm teeb tsa
Nyob rau hauv ib txwm ua hauj lwm ib puag ncig ntawm uplink tawg optical zog ntawm -24.0 dBm, optical teeb liab tawm los ntawm tawg lub teeb qhov chaw yog siv raws li qhov ntsuas pib taw tes, thiab lub module tau txais thiab tsim ib tug tiav hluav taws xob teeb liab raws li qhov ntsuas kawg taw tes, ignoring lub lub sij hawm ncua ntawm lub teeb nyob rau hauv lub xeem fiber.Qhov ntsuas 1G tawg txais tos teeb lub sij hawm yog 76.7 ns, uas ua tau raws li lub thoob ntiaj teb tus qauv ntawm <400 ns;lub sijhawm 10G tawg txais tos yog 241.8 ns, uas kuj ua tau raws li tus qauv thoob ntiaj teb ntawm <800 ns.
3. Cov txiaj ntsig thiab kev tshuaj xyuas
Qhov ntsuas ntsuas tseem ceeb ntawm 10G EPON symmetric OLT optical module suav nrog lub sijhawm teeb tsa lub txais, txais lub siab xav, thiab xa daim duab qhov muag.Cov kev ntsuam xyuas tshwj xeeb yog raws li hauv qab no:
(1) Tau txais lub sijhawm teeb tsa
Nyob rau hauv ib txwm ua hauj lwm ib puag ncig ntawm uplink tawg optical zog ntawm -24.0 dBm, optical teeb liab tawm los ntawm tawg lub teeb qhov chaw yog siv raws li qhov ntsuas pib taw tes, thiab lub module tau txais thiab tsim ib tug tiav hluav taws xob teeb liab raws li qhov ntsuas kawg taw tes, ignoring lub lub sij hawm ncua ntawm lub teeb nyob rau hauv lub xeem fiber.Qhov ntsuas 1G tawg lub sijhawm txais tos yog 76.7 ns, uas ua tau raws li tus qauv thoob ntiaj teb ntawm <400 ns;lub sijhawm 10G tawg txais tos yog 241.8 ns, uas kuj ua tau raws li tus qauv thoob ntiaj teb ntawm <800 ns.
