Basic tswvyim ntawm optical fiber kev sib txuas lus.
Ib qho hluav taws xob kho qhov muag yog dielectric optical waveguide, cov qauv waveguide uas thaiv lub teeb thiab nthuav tawm lub teeb nyob rau hauv cov kev taw qhia axial.
Zoo heev fiber ntau ua los ntawm quartz iav, hluavtaws cob, thiab lwm yam.
Ib hom fiber ntau: core 8-10um, cladding 125um
Multimode fiber ntau: core 51um, cladding 125um
Txoj kev sib txuas lus ntawm kev xa cov teeb liab kho qhov muag siv optical fibers hu ua optical fiber kev sib txuas lus.
Lub teeb tsis muaj nyob rau hauv qeb ntawm electromagnetic tsis.
Lub wavelength ntau ntawm pom lub teeb yog 390-760 nm, qhov loj dua 760 nm yog lub teeb infrared, thiab qhov me dua 390 nm yog lub teeb ultraviolet.
Lub teeb yoj lub qhov rais ua haujlwm (peb qhov rais sib txuas lus):
Lub wavelength ntau yam siv nyob rau hauv fiber-optic kev sib txuas lus yog nyob ze-infrared cheeb tsam
Short-wavelength cheeb tsam (pom pom lub teeb, uas yog lub teeb txiv kab ntxwv los ntawm qhov muag liab qab) 850nm txiv kab ntxwv lub teeb
Ntev wavelength cheeb tsam (tsis pom lub teeb cheeb tsam) 1310 nm (theoretical yam tsawg kawg nkaus dispersion point), 1550 nm (theoretical yam tsawg kawg nkaus attenuation point)
Fiber qauv thiab kev faib tawm
1.Cov qauv ntawm cov fiber ntau
Cov qauv fiber ntau zoo tshaj plaws: core, cladding, txheej, tsho.
Cov tub ntxhais thiab cladding yog ua los ntawm cov khoom siv quartz, thiab cov khoom siv kho tshuab yog qhov tsis yooj yim thiab yooj yim tawg.Yog li ntawd, ob txheej txheej txheej txheej, ib hom resin thiab ib txheej ntawm nylon hom feem ntau ntxiv, yog li ntawd qhov kev ua tau zoo ntawm cov fiber ntau ncav cuag cov kev xav tau ntawm qhov project.
2.Classification ntawm optical fibers
(1) Cov fiber ntau tau muab faib raws li qhov ntsuas qhov taw qhia ntawm qhov sib txawv ntawm cov fiber ntau: nws muab faib ua cov kauj ruam hom fiber ntau (uniform fiber) thiab qib fiber ntau (non-uniform fiber).
Nco ntsoov tias cov tub ntxhais muaj qhov ntsuas qhov ntsuas ntawm n1 thiab cladding refractive index yog n2.
Txhawm rau ua kom cov tub ntxhais xa cov teeb pom kev mus ntev, qhov tsim nyog rau kev tsim kho qhov muag fiber ntau yog n1>n2.
Lub refractive index faib ntawm ib tug niaj hnub fiber ntau yog tas mus li
Lub refractive index faib txoj cai ntawm non-uniform fiber:
Ntawm lawv, △ – txheeb ze refractive index sib txawv
Α-refractive index, α = ∞-qib-hom refractive index faib fiber ntau, α = 2-square-txoj cai refractive index faib fiber ntau (ib qib fiber ntau).Qhov no fiber ntau yog piv rau lwm cov qib fibers.Mode dispersion yam tsawg kawg nkaus pom.
(1) Raws li tus naj npawb ntawm hom kis tau tus mob hauv cov tub ntxhais: muab faib ua ntau hom fiber ntau thiab ib hom fiber ntau
Cov qauv ntawm no yog hais txog kev faib tawm ntawm qhov chaw electromagnetic ntawm lub teeb xa mus rau hauv ib qho khoom siv fiber ntau.Kev faib tawm txawv teb yog hom sib txawv.
Ib hom (tsuas yog ib hom kis tau tus mob hauv fiber ntau), multimode (ntau hom yog ib txhij kis hauv fiber ntau)
Tam sim no, vim tias qhov kev xav tau nce ntxiv ntawm kev sib kis tus nqi thiab kev sib kis ntau ntxiv, lub nroog loj hauv cheeb tsam network tau txhim kho nyob rau hauv cov kev taw qhia ntawm kev kub ceev thiab muaj peev xwm loj, yog li feem ntau ntawm lawv yog ib hom stepped fibers.(Cov yam ntxwv kis tau tus mob ntawm nws tus kheej zoo dua li multimode fiber ntau)
(2) Cov yam ntxwv ntawm optical fiber ntau:
① Poob cov yam ntxwv ntawm cov khoom siv kho qhov muag: Lub teeb nthwv dej tau xa mus rau hauv cov khoom siv kho qhov muag, thiab lub zog kho qhov muag maj mam txo qis thaum qhov sib kis tau nce.
Qhov ua rau poob fiber ntau muaj xws li: kev sib txuas poob, kev nqus tsis zoo, tawg tawg, thiab khoov hluav taws xob poob.
Coupling poob yog qhov poob los ntawm kev sib txuas ntawm cov fiber ntau thiab cov cuab yeej.
Absorption poob yog tshwm sim los ntawm kev nqus ntawm lub teeb lub zog los ntawm cov ntaub ntawv fiber ntau thiab impurities.
Kev tawg tawg yog muab faib ua Rayleigh scattering (refractive index non-uniformity) thiab waveguide scattering (khoom unevenness).
Txoj kev khoov hluav taws xob poob yog qhov poob uas tshwm sim los ntawm kev khoov ntawm cov fiber ntau uas ua rau cov kab hluav taws xob uas tshwm sim los ntawm kev khoov ntawm cov fiber ntau.
②Dispersion yam ntxwv ntawm optical fiber: sib txawv zaus Cheebtsam nyob rau hauv lub teeb liab kis tau los ntawm lub optical fiber muaj sib txawv kis ceev, thiab lub cev tshwm sim ntawm distortion tshwm sim los ntawm lub teeb liab mem tes broadning thaum mus txog lub davhlau ya nyob twg hu ua dispersion.
Lub dispersion yog muab faib ua modal dispersion, khoom dispersion, thiab waveguide dispersion.
Basic Cheebtsam ntawm optical fiber kev sib txuas lus systems
Xa ib feem:
Lub pulse modulation teeb liab tso zis los ntawm hluav taws xob transmitter (hluav taws xob davhlau ya nyob twg) yog xa mus rau lub optical transmitter (lub teeb liab xa los ntawm qhov kev pab cuam-tswj hloov yog ua tiav, lub waveform yog zoo li tus, lub inverse ntawm tus qauv yog hloov ... thiab xa mus rau optical transmitter)
Lub luag haujlwm tseem ceeb ntawm optical transmitter yog hloov hluav taws xob teeb liab mus rau hauv lub teeb liab optical uas txuas rau hauv fiber ntau.
Txais ib feem:
Hloov kho qhov muag teeb liab kis tau los ntawm optical fibers rau hauv cov teeb liab hluav taws xob
Kev ua haujlwm ntawm cov teeb liab hluav taws xob tau rov qab mus rau qhov qub pulse modulated teeb liab thiab xa mus rau lub davhlau ya nyob twg hluav taws xob (cov teeb liab hluav taws xob xa los ntawm lub tshuab txais optical tau ua tiav, lub waveform yog zoo li tus, lub inverse ntawm tus qauv yog inverted ... qhov tsim nyog hluav taws xob teeb liab yog xa rov qab mus rau lub programmable hloov)
Qhov kis tau tus mob:
Ib hom fiber ntau, optical repeater (hluav taws xob regenerative repeater (optical-hluav taws xob-optical conversion amplification, kis tau tus mob ncua yuav loj dua, mem tes txiav txim Circuit Court yuav siv los ua tus waveform, thiab sij hawm), erbium-doped fiber Amplifier (ua tiav lub amplification nyob rau theem kho qhov muag, tsis muaj waveform shaping)
(1) Optical transmitter: Nws yog optical transceiver uas paub txog hluav taws xob / kho qhov muag hloov pauv.Nws muaj lub teeb ci, tus tsav tsheb thiab tus modulator.Lub luag haujlwm yog los hloov lub teeb nthwv dej ntawm lub tshuab hluav taws xob mus rau lub teeb nthwv dej tawm los ntawm lub teeb ci los ua ib qho tsis muaj zog, thiab tom qab ntawd ob peb lub teeb liab hloov kho qhov muag mus rau optical fiber lossis optical cable rau kev sib kis.
(2) Optical receiver: yog optical transceiver uas paub txog kev hloov kho qhov muag / hluav taws xob.Cov qauv siv hluav taws xob yog tsim los ntawm lub teeb pom kev sib txuas thiab lub tshuab hluav taws xob kho qhov muag, thiab lub luag haujlwm yog los hloov cov teeb liab kho qhov muag kis los ntawm optical fiber lossis optical cable rau hauv lub teeb liab hluav taws xob los ntawm lub teeb pom kev kho qhov muag, thiab tom qab ntawd ua kom lub zog hluav taws xob tsis muaj zog. ib theem txaus los ntawm amplifying Circuit Court xa mus rau lub teeb liab.Qhov tau txais qhov kawg ntawm lub tshuab hluav taws xob mus.
(3) Fiber / Cable: Fiber lossis cable tsim txoj kev sib kis ntawm lub teeb.Lub luag haujlwm yog xa cov teeb liab dimmed xa los ntawm qhov kawg xa mus rau qhov muag pom ntawm qhov tau txais qhov kawg tom qab kev sib kis mus ntev los ntawm cov khoom siv kho qhov muag lossis cov kab hluav taws xob kho qhov muag kom ua tiav cov haujlwm ntawm kev xa cov ntaub ntawv.
(4) Optical repeater: muaj lub photodetector, lub teeb ci, thiab kev txiav txim siab rov tsim dua.Muaj ob txoj haujlwm: ib qho yog los them nyiaj rau qhov attenuation ntawm cov teeb liab kho qhov muag xa mus rau hauv cov khoom siv fiber ntau;lwm qhov yog los tsim cov mem tes ntawm lub waveform distortion.
(5) Passive Cheebtsam xws li fiber ntau optic connectors, couplers (tsis tas yuav muab fais fab sib cais, tab sis cov cuab yeej tseem poob): Vim tias qhov ntev ntawm fiber ntau los yog cable raug txwv los ntawm cov txheej txheem kev kos duab fiber ntau thiab kev tsim kho cable, thiab ntev ntawm cov fiber ntau kuj txwv (piv txwv li 2km).Yog li ntawd, tej zaum yuav muaj teeb meem uas ib tug ntau ntawm optical fibers txuas nyob rau hauv ib tug optical fiber kab.Yog li ntawd, kev sib txuas ntawm optical fibers, kev sib txuas thiab kev sib txuas ntawm optical fibers thiab optical transceivers, thiab kev siv cov khoom siv passive xws li optical connectors thiab couplers yog indispensable.
Lub superiority ntawm optical fiber kev sib txuas lus
Kev sib kis bandwidth, muaj peev xwm sib txuas lus loj
Tsawg kis tsis tau thiab loj relay nrug
Muaj zog tiv thaiv electromagnetic cuam tshuam
(Beyond wireless: wireless signals muaj ntau yam teebmeem, multipath txiaj ntsig, duab ntxoov ntxoo los, Rayleigh fading, Doppler teebmeem
Piv nrog coaxial cable: optical teeb liab yog loj dua coaxial cable thiab muaj kev ruaj ntseg zoo)
Qhov zaus ntawm lub teeb nthwv dej yog qhov siab heev, piv nrog rau lwm cov hluav taws xob hluav taws xob, qhov cuam tshuam me me.
Qhov tsis zoo ntawm cov khoom siv kho qhov muag: cov khoom siv tsis zoo, yooj yim tawg, (txhim kho cov khoom siv kho qhov muag, yuav muaj kev cuam tshuam rau kev cuam tshuam), nws yuav siv sij hawm ntev los tsim, thiab cuam tshuam los ntawm thaj chaw.