Round PM fiber ntau
Lub tswv yim ntawm ncig birefringence tuaj yeem nkag mus rau hauv cov fiber ntau, yog li ob txoj cai-polarization hom yog ncig polarized clockwise thiab counterclockwise hauv fiber ntau -- lub thiaj li hu ua ncig PM fiber. Txoj hauv kev zoo tshaj plaws kom ua tiav lub nplhaib birefringence nyob rau hauv ib ncig (axially symmetric) optical fiber yog ntswj cov fiber ntau, uas ua rau muaj qhov sib txawv ntawm kev nthuav dav ntawm cov oscillating lub ntsiab hom ntawm ncig polarization nyob rau hauv clockwise thiab counterclockwise cov lus qhia. Yog li, cov qauv ntawm ob lub voj voog polarized no yog decoupled. Nws tseem tuaj yeem txiav txim siab tias qhov kev ntxhov siab sab nraud tuaj yeem hloov pauv lub azimuth Lub kaum sab xis ntawm qhov ntev fiber ntau, uas tuaj yeem tsim lub nplhaib birefringence ntawm fiber ntau. Yog hais tias lub fiber ntau yog twisted, ib tug torsion kev nyuaj siab yog generated, uas ua rau cov khoom kho qhov muag txuam nrog distortion.
Cov tub ntxhais ntawm cov fiber ntau kuj tuaj yeem muab tso rau ntawm txoj kev kauv hauv cov cladding, kom lub nplhaib birefringence tuaj yeem tau txais. Qhov no ua rau lub teeb mus raws txoj kev kauv, ua rau kev sib hloov kho qhov muag. Birefringence tuaj yeem ua tiav tsuas yog vim muaj kev cuam tshuam ntawm geometry. Xws li cov fiber ntau tuaj yeem siv los ua ib hom fiber ntau, thiab nws yuav ua rau poob qis hauv hom kev txiav txim siab.
Lub annular PM fiber ntau nrog helical fiber core qauv tuaj yeem siv rau hauv thaj chaw ntawm kev paub txog tam sim no raws li Faraday Effect. Optical fibers tuaj yeem ua tau siv cov pas nrig bimetallic thiab cov raj preformed, uas tig cov raj preformed los ua cov spirals thaum lub sij hawm kos duab fiber ntau.
Linear PM fiber ntau
Muaj ob lub ntsiab ntawm LINEAR PM fiber ntau, uas yog ib hom polarization thiab birefringence hom. Piv nrog rau ob hom polarization yooj yim, tus yam ntxwv tseem ceeb ntawm ib hom polarization yog tias nws muaj kev sib kis loj. Rau hom birefringence fiber ntau, qhov kev nthuav tawm tsis tu ncua ntawm ob hom polarization hauv hom tseem ceeb ntawm oscillation yog qhov sib txawv. Ntau qhov kev tsim kho qhov muag fiber ntau tuaj yeem siv los tswj cov kab polarization, uas yuav tau tham tom qab.
Edge slots thiab ntug tunnels linear PM fiber ntau
Lub ntug-slot fiber ntau sib xyaw ua ke ob lub qhov nrog qhov ntsuas qhov ntsuas qis qis dua li qhov ntsuas cladding. Cov slots yog nyob rau ntawm ob sab ntawm lub hauv paus fiber core. Hom fiber ntau no muaj W-shaped refractive index faib raws X-axis thiab ib kauj ruam refractive index faib raws Y-axis. Lub ntug-tunnel fiber yog ib qho piv txwv tshwj xeeb ntawm ntug-qhov qauv. Nyob rau hauv cov kab PM fibers, geometric anisotropy yog nkag mus rau hauv cov tub ntxhais fiber ntau kom tau txais cov fibers birefringence.
Linear PM fiber ntau nrog cov ntsiab lus nyuaj
Ib txoj hauv kev zoo los qhia siab birefringence rau hauv cov fiber ntau yog qhia cov kev ntxhov siab tsis zoo nrog ob chav geometric symmetry rau hauv cov tub ntxhais fiber ntau. Raws li qhov tshwm sim ntawm cov duab elastic nyhuv, qhov kev ntxhov siab hloov pauv qhov ntsuas qhov ntsuas ntawm cov tub ntxhais fiber ntau, uas tuaj yeem pom los ntawm cov qauv polarization raws cov spindle fiber ntau thiab cov txiaj ntsig ntawm birefringence. Qhov xav tau kev ntxhov siab tuaj yeem tau txais los ntawm kev siv ob qhov sib npaug thiab ntawm nws tus kheej kev ntxhov siab (SAPs) nyob rau hauv thaj tsam cladding tawm tsam cov tub ntxhais fiber ntau. Yog li ntawd, tsuav yog qhov Performance index ntawm refraction ntawm SAPs qis dua los yog sib npaug rau qhov ntsuas ntawm refraction ntawm cladding, yuav tsis muaj ob hom oscillation los ntawm SAPs.
Cov duab zoo tshaj plaws uas siv rau SAPs yog lub hneev khi zoo thiab lub voj voog. Cov fibers no hu ua bow-tie thiab panda fibers feem. Qhov hla ntawm ob lub fibers no tau qhia hauv daim duab hauv qab no. Lub modal birefringence siv nyob rau hauv cov fibers sawv cev rau geometric thiab stress-induced birefringence. Lub geometric birefringence yog me me heev thiab tuaj yeem tsis quav ntsej rau lub voj voog core fiber. Nws tau raug pom tias qhov birefringence ntawm cov cores fiber ntau tuaj yeem txhim kho thaum SAPs tau muab tso rau ze rau ntawm cov tub ntxhais fiber ntau, tab sis nws yuav tsum tau muab tso rau ze ze ntawm cov tub ntxhais fiber ntau kom tsis txhob muaj qhov poob ntawm fiber ntau, tshwj xeeb tshaj yog tias cov khoom ntawm SAPs tsis yog silicon dioxide. Panda fiber ntau tau raug txhim kho kom ua tiav hom birefringence siab dua, poob qis heev thiab qis crosstalk.
Tswv yim: Tam sim no, nrov tshaj plaws PMfiber ntauhauv kev lag luam yog puag ncig Panda fiber ntau. Panda fiber ntau qhov zoo dua lwm cov PM fibers yog fiber ntau thiab cov lej aperture piv rau cov qauv ib hom fiber ntau. Qhov tsawg kawg nkaus poob ntawm lub cuab yeej yog xyuas kom meej thaum siv ob hom teeb.
Linear PM fiber nrog elliptic qauv
Thawj qhov kev sim kev tshawb fawb ntawm cov tswv yim tsis tshua muaj ib leeg-polarization fibers ntawm peb hom kev kho qhov muag tau ua tiav: elliptic core, elliptic cladding thiab elliptic sheath fiber. Kev tshawb fawb thaum ntxov ntawm elliptic fiber core cable suav nrog kev suav ntawm polarization birefringence. Hauv thawj theem, cov duab plaub dielectric waveguide yog siv los kwv yees lub birefringence ntawm elliptic core fiber. Hauv kev sim siv PM fiber ntau thawj zaug, ib hom fiber ntau nrog dumbbell zoo li cov tub ntxhais fiber ntau tau tsim. Lub polarization tuav ntev tuaj yeem raug txo los ntawm kev nce qhov sib txawv ntawm qhov sib txawv ntawm fiber ntau cladding. Txawm li cas los xij, vim muaj kev txwv tsis pub siv, nws tsis tuaj yeem ua kom qhov refractive index sib txawv ntau dhau. Kev nce qhov ntsuas qhov sib txawv ntawm qhov sib txawv ua rau kev sib kis tsis tau, thiab kev sib txuas yuav nyuaj dua vim tias lub vojvoog tseem ceeb yuav tsum raug txo. Tus nqi birefringence raug rau elliptic fiber ntau yog siab dua li rau elliptic cladding fiber. Tab sis qhov poob ntawm elliptic fiber core yog siab dua li ntawm elliptic claddingfiber ntau.
Linear PM fiber nrog refractive index modulation
Rau ib leeg-polarized fiber uas cais qhov kev txiav tawm wavelength ntawm ob lub kaum sab xis oscillations, ib txoj hauv kev los ua kom nws cov zaus band dav yog xaiv ib qho refractive index faib uas tsuas tso cai rau ib lub xeev polarization nyob rau ntawm qhov kev txiav tawm. Lub siab birefringence tuaj yeem ua tiav los ntawm kev qhia angular modulation rau sab hauv cladding Performance index ntawm peb txheej elliptical cross-section fiber. Hauv kev kawm ntawm peb txheej elliptical cross-section optical fibers, ib txoj hauv kev perturbation yog saws, nyob rau hauv uas lub duab plaub fiber core waveguide yog assumed raws li cov qauv siv. Nyob rau hauv ib qho kev ua haujlwm polarization, kev sim birefringence ntawm peb txheej ntawm ellipsoidal fiber ntau qhia tau hais tias tsim nyog angular modulation ntawm lub puab cladding Performance index tuaj yeem txhim kho birefringence thiab txuas lub wavelength ntau.
Lub refractive index faib yog hu ua npauj npaim profile. Qhov no yog ib qho asymmetric W contour, uas yog tsim los ntawm cov tub ntxhais fiber ntau zoo ib yam thiab cladding nyob ib puag ncig cov tub ntxhais fiber ntau. Nyob rau hauv lub cladding, lub contour muaj qhov siab tshaj plaws tus nqi ntawm NCL, thiab hloov mus rau hauv lub vojvoog thiab lub kaum sab xis, thiab muaj qhov siab tshaj plaws descending mob raws X-axis. Muaj ob lub zog ntawm cov duab no kom paub txog tib hom kev ua haujlwm polarization. Ua ntej, cov duab yog asymmetrical, uas yuav ua rau cov propagation tsis tu ncua ntawm ob lub ntsiab hom ntawm oscillation ntawm txoj cai kaum sib txawv, thiab thib ob, lub attenuation nyob rau hauv lub tsev fuabtais xyuas kom meej tias txhua hom muaj ib tug cutoff wavelength. Npauj npaim fibers muaj qhov tsis muaj zog conductivity, yog li cov lus teb rau qhov sib npaug ntawm scalar yoj siv tau los txiav txim siab hom teb thiab kev nthuav tawm tas li. Cov lus teb hais txog trigonometric functions thiab Mathieu functions, uas yog siv los piav qhia txog kev sib raug zoo ntawm transverse coordinates nyob rau hauv lub cladding.fiber ntau. Cov kev ua haujlwm no tsis yog kev sib raug zoo rau ib leeg, uas yuav tsum muaj kev ua haujlwm tsis kawg los suav rau cov qauv hauv cheeb tsam sib txawv thiab kom txaus siab rau ciam teb. Qhov tshwm sim geometric birefringence graph, piv nrog tus qauv zaus V, qhia tau hais tias qhov degree ntawm qhov refractive index poob raws X-axis nce asymmetry, yog li nce qhov siab tshaj plaws thiab V qhov tseem ceeb ntawm birefringence. Tus nqi siab tshaj ntawm birefringence yog cov yam ntxwv ntawm cov fibers uas tsis yog voj voog. Hom birefringence tuaj yeem txhim kho los ntawm kev qhia anisotropy rau hauv cov fiber ntau. Rau anisotropy, nws tuaj yeem ua tiav los ntawm kev muab qhov sib txawv refractive index distributions rau ob lub polarizations ntawm ib hom. Geometric birefringence tsawg dua anisotropic birefringence. Txawm li cas los xij, qhov poob ntawm npauj npaim zoo cladding tuaj yeem muab ob npaug rau polarization rau oscillating main mode cutoff wavelength, uas yog sib cais los ntawm lub qhov rais wavelength nyob rau hauv uas nws muaj peev xwm mus cuag ib tug polarization ib hom lag luam.
