Dab tsi yog fiber ntau dispersion?Yuav ua li cas them nyiaj dispersion?
Dab tsi yog fiber dispersion?
Fiber dispersion qhia txog kev nthuav tawm lub xeev ntawm cov teeb liab tawm tswv yim hauv fiber ntau. Nws hais txog lub teeb liab distortion tshwm sim los ntawm kev nthuav tawm ntawm cov khoom sib txawv los yog cov hom sib txawv ntawm cov teeb liab optical ntawm qhov sib txawv speeds.Nws feem ntau suav nrog peb kis: intermode dispersion, chrominance dispersion thiab polarization hom dispersion.
Intermodal dispersion
Intermode dispersion yog lub teeb liab distortion mechanism uas tshwm sim nyob rau hauv multimode fibers thiab lwm yam waveguides.Nyob rau hauv ib tug multimode fiber, lub teeb rays nkag mus rau lub fiber nyob rau hauv sib txawv lub kaum sab xis yog txhais raws li ib txoj kev los yog ib tug qauv. Kev sib kis ceev (piv txwv li, pab pawg ceev) kuj sib txawv, yog li muaj lub sijhawm sib txawv ntawm cov teeb liab kis tau tus mob mus txog qhov chaw kho qhov muag fiber ntau. Feem ntau, qee lub teeb hla ncaj qha los ntawm cov tub ntxhais (hauv hom axial), thaum lwm tus thaws rov qab. thiab tawm ntawm cladding/core ciam teb thiab mus ncig zigzag raws waveguide, raws li qhia nyob rau hauv cov kauj ruam-index multimode fiber hauv qab no.Qhov tseeb yog tias sai li sai tau lub teeb yog refracted, intermode/hom dispersion tshwm sim.Ntawm lawv, inter-mode dispersion. yog zoo correlated nrog txoj kev kis tau tus mob, uas yog, inter-mode dispersion tshwm sim los ntawm lub high-order hom (ray nkag mus rau ntawm ib tug loj lub kaum sab xis rau ib tug ntev deb) yog siab tshaj qhov uas tshwm sim los ntawm qhov tsawg. -kev txiav txim hom (txoj kab hluav taws xob nkag ntawm lub kaum sab xis me dua rau qhov luv luv).
1 Intermode dispersion nyob rau hauv step-index multimode fibers
Multimode fiber ntau tuaj yeem ua raws li 17 ray propagation hom tib lub sijhawm, thiab nws cov intermode dispersion yog ntau dua li ntawm ib hom fiber ntau.Qhov no yog vim ib hom fibers muaj ib hom propagation, piv txwv li lub teeb mus raws cov tub ntxhais (axial. hom) yam tsis muaj kev cuam tshuam ntawm cov ciam teb cladding, yog li tsis muaj intermode dispersion tshwm sim.Txawm li cas los xij, yog siv cov graded index multimode fiber ntau, qhov teeb meem no txawv.Txawm hais tias lub teeb kuj propagates nyob rau hauv ntau hom, vim lub uneven refractive index ntawm lub fiber core, txoj kev ntawm lub teeb rays tsis yog ib txoj kab ncaj nraim tab sis txoj kab nkhaus, thiab kev nthuav tawm ceev ntawm lub teeb rays kuj hloov. Yog li ntawd, inter-mode dispersion tuaj yeem txo qis heev los ntawm kev xaiv qhov tsim nyog refractive index faib.
Chroma dispersion
Chrominance dispersion yog hais txog kev nthuav dav ntawm optical pulses tshwm sim los ntawm cov pab pawg sib txawv ntawm cov sib txawv wavelength Cheebtsam nyob rau hauv lub optical fiber, nrog rau cov khoom dispersion thiab waveguide dispersion.
2 Chrominance dispersion
Cov ntaub ntawv dispersion yog tshwm sim los ntawm dependence ntawm refractive index ntawm lub wavelength ntawm cov khoom tseem ceeb, thaum lub waveguide dispersion yog tshwm sim los ntawm dependence ntawm hom propagation tas li ntawm cov fiber ntau tsis (core radius, qhov sib txawv ntawm refractive index ntawm cov tub ntxhais thiab lub cladding) thiab lub teeb liab wavelength.Ntawm qee zaus, cov khoom siv dispersion thiab waveguide dispersion tuaj yeem tshem tawm ib leeg tawm, kom lub wavelength approximating 0 chroma dispersion tau txais.Qhov tseeb, chrominance dispersion tsis yog ib txwm muaj kev puas tsuaj. Lub teeb mus los. ntawm qhov sib txawv ntawm qhov sib txawv ntawm qhov sib txawv wavelengths los yog cov ntaub ntawv, ua rau lub teeb pulses yuav broadened los yog compressed nyob rau hauv fiber ntau, uas ua rau nws muaj peev xwm customize refractive index profiles los tsim fibers rau txawv hom phiaj.G.652 optical fiber yog ib qho piv txwv.
Polarization hom dispersion
Polarization hom dispersion (PMD) qhia txog polarization dependence ntawm kev nthuav tawm yam ntxwv ntawm lub teeb tsis nyob rau hauv optical fibers.Hauv qhov tseeb optical fibers, muaj ob hom polarization uas yog perpendicular rau ib leeg. Qhov zoo tshaj plaws, ob hom polarization yuav tsum muaj tib lub nthwv dej propagation yam ntxwv, tab sis feem ntau, muaj qhov sib txawv me me ntawm cov qauv polarization sib txawv.Qhov no yog vim qhov hloov pauv lossis cuam tshuam ntawm qhov kub thiab txias, siab thiab lwm yam hauv cov txheej txheem propagation, ua rau sib txawv. kis tau tus mob ceev ntawm ob hom polarization, ua rau lub sij hawm ncua thiab polarization hom dispersion.
3 Polarization hom dispersion tsim
Polarization hom dispersion muaj kev cuam tshuam me ntsis rau cov tes hauj lwm nrog kev sib txuas ceev hauv qab 2.5Gbps, txawm tias qhov sib kis tau ntau dua 1000 km.Txawm li cas los xij, nrog kev nce ntawm kev sib kis ceev, tshwj xeeb tshaj yog thaum kis ceev tshaj 10Gbps, qhov cuam tshuam ntawm polarization hom dispersion nce. dramatically, thiab dhau los ua fiber ntau parameter uas tsis tuaj yeem ignored.Polarization hom dispersion yog tsuas yog tsim nyob rau hauv cov txheej txheem ntawm iav manufacturing, ntxiv rau qhov kho qhov muag fiber thaiv, installation thiab siv ib puag ncig thiab lwm yam yuav cuam tshuam rau nws.
Yuav ua li cas them nyiaj dispersion?
Txawm hais tias fiber ntau dispersion tsis ua rau lub teeb liab tsis muaj zog, nws shortens qhov kev ncua deb ntawm lub teeb liab nyob rau hauv lub fiber ntau thiab ua rau lub teeb liab distortion nyob rau tib lub sij hawm.Piv txwv li, lub teeb mem tes ntawm 1 nanosecond ntawm qhov kawg transmitting yuav broadened mus rau 10 nanoseconds ntawm lub tau txais qhov kawg, ua rau lub teeb liab tsis tau txais thiab txiav txim siab kom raug.Yog li ntawd, nws yog ib qho tseem ceeb heev kom txo tau cov fiber ntau dispersion los yog them rau nws nyob rau hauv kev sib txuas mus ntev xws li ntom wavelength division multiplexing (DWDM). Peb feem ntau siv dispersion nyiaj pab tswv yim. thiab cov txheej txheem tau qhia hauv qab no.
Dispersion compensated fiber ntau
Siv cov txheej txheem ntawm dispersion-compensated fiber (DCF), qhov tsis zoo dispersive fiber ntau tuaj yeem muab ntxiv rau cov pa fiber ntau.Piv rau cov pa fiber ntau, tus nqi dispersion yog loj heev, thiab dispersion yog qhov zoo, uas ua rau lub teeb faib hauv qhov no. hom fiber ntau txo lossis txawm ploj mus.Los ntawm kev ntxiv qhov tsis zoo dispersion them nyiaj fiber ntau rau nws, tag nrho cov dispersion ntawm tag nrho cov kab fiber ntau tuaj yeem kwv yees li xoom, kom paub txog kev kub ceev, muaj peev xwm loj thiab kev sib txuas lus ntev.Dispersion nyiaj fiber ntau muaj peb. Cov txheej txheem them nyiaj, suav nrog cov nyiaj them ua ntej, cov nyiaj them rov qab thiab kev them nyiaj symmetry.Dispersion them nyiaj fibers tau dav siv los txhim kho fiber ntau txuas ntsia ntawm 1310 nm los ua haujlwm ntawm 1550 nm.
4 Peb dispersion them nyiaj mechanisms
Fiber Bragg grating
Fiber Bragg Grating (FBG) yog ib qho khoom siv rov qab los ntawm cov fiber ntau, uas tuaj yeem hloov kho nws cov core refractive Performance index nyob rau hauv ib tug tej thaj chaw deb tswj systems xws li 100 km, lub dispersion nyhuv yuav txo tau los ntawm no ntaus ntawv. beam dhau los ntawm fiber ntau Bragg grating, lub wavelength ua tau raws li qhov kev hloov kho yuav raug cuam tshuam, thiab tus so wavelength yuav txuas ntxiv mus rau hauv cov fiber ntau los ntawm fiber ntau Bragg grating.Siv fiber Bragg grating rau dispersion them muaj txiaj ntsig zoo, vim fiber Bragg. grating tuaj yeem ua ke nrog lwm cov khoom siv hluav taws xob tsis zoo, tsis muaj qhov nkag tsis zoo thiab tus nqi qis. Tsis tas li ntawd, fiber ntau Bragg grating tuaj yeem siv tsis tau tsuas yog ua cov lim dej rau dispersion nyiaj, tab sis kuj yog lub sensor, wavelength stabilizer rau pumped lasers, thiab nqaim-band WDM ntxiv / rho tawm lim.
Electron dispersion them nyiaj
Electronic dispersion them nyiaj (EDC) yog ib txoj hauv kev kom ua tiav kev them nyiaj dispersion hauv kev sib txuas lus kho qhov muag siv hluav taws xob lim (tseem hu ua kev sib npaug), uas yog, lim hauv kev sib txuas lus kom them nyiaj rau cov teeb liab attenuation los ntawm qhov nruab nrab kis tau tus mob. feem ntau pom tau los ntawm cov lim transverse, uas nws cov zis yog qhov hnyav ntawm cov khoom siv qeeb. Nws tuaj yeem hloov kho qhov hnyav hnyav raws li cov yam ntxwv ntawm lub teeb liab tau txais, uas yog, kev hloov kho tus kheej.Electronic dispersion them nyiaj siv tau rau hauv ib hom fiber ntau tshuab thiab ntau hom fiber ntau tshuab. Tsis tas li ntawd, nws tuaj yeem ua ke nrog lwm cov nta rau 10Gbit / s receiver integrated circuits.Nws tuaj yeem txo tus nqi transmitter hauv ib hom fiber ntau tshuab, thiab tuaj yeem ua rau kom muaj kev sib kis ntawm ntau hom fiber ntau nrog cov nqi txais me me. .
Xaus
Txawm hais tias optical fiber dispersion tuaj yeem cuam tshuam cov teeb liab tawm hauv ntau txoj hauv kev, thiab txawm tias ua rau teeb liab distortion, nws tsis yog qhov tsis zoo rau cov teeb liab kis tau tus mob hauv qhov txuas fiber ntau. cov nyhuv nonlinear.Thaum lub dispersion ntawm fiber ntau dhau lawm, cov saum toj no dispersion them nyiaj fiber, fiber Bragg grating, electron dispersion nyiaj thiab lwm txoj kev yuav raug xaiv rau dispersion nyiaj.