Qhov sib txawv tseem ceeb ntawm modal thiab chromatic dispersion yog tias modal dispersion tuaj yeem tshwm sim nrog lub teeb pom kev monochromatic, whereas chromatic dispersion tsis tuaj yeem tshwm sim nrog lub teeb ci monochromatic.
Modal thiab chromatic dispersion yog cov ntsiab lus tseem ceeb hauv kev piav qhia cov khoom siv kho qhov muag ntawm optical fibers. Modal dispersion yog ib hom kev distortion mechanism uas qhov distortion tshwm sim nyob rau hauv multimode fibers thiab lwm yam waveguides. Chromatic dispersion yog qhov tshwm sim los ntawm qhov sib txawv spectral Cheebtsam ntawm ib tug mem tes mus txawv tebchaws.
Modal Dispersion yog dab tsi?
Modal dispersion yog ib hom kev hloov pauv ntawm cov txheej txheem uas qhov kev cuam tshuam tshwm sim hauv ntau hom fibers thiab lwm yam waveguides. Ntawm no, cov teeb liab kis tau nrog lub sijhawm vim tias qhov kev nthuav tawm ntawm cov teeb liab optical tsis zoo ib yam rau txhua hom. Muaj qee lub npe rau modal dispersion xws li multimode distortion, multimode dispersion, modal distortion, intermodal distortion, thiab lwm yam.
Thaum tus txheej txheem ntawm modal dispersion nyob rau hauv ray optics analogy, rays ntawm lub teeb nkag mus rau hauv fiber ntau nrog cov ces kaum sib txawv rau lub fiber axis (qhov txawv tshwm sim mus txog rau lub txais lub kaum sab xis ntawm lub fiber). Lub teeb rays uas nkag mus rau hauv fiber ntau nrog cov kaum sab xis cam taug kev ncaj nraim. Tsis tas li ntawd, cov rays no tuaj txog sai dua cov rays uas nkag mus rau ntawm lub kaum sab xis.
Daim duab 01: Optical Fiber
Ntxiv mus, modal dispersion tuaj yeem txwv qhov bandwidth ntawm multimode fibers. Siv cov tub ntxhais fiber ntau uas muaj cov qhab nia refractive index profile tuaj yeem txo qhov kev cuam tshuam ntawm modal dispersion, tab sis nws tsis tuaj yeem tshem tawm tag nrho. Piv txwv li, multimode graded-index fiber ntau muaj bandwidth tshaj 3.5 GHz.km ntawm 850 nm yog tsim los siv.
PMD lossis polarization hom dispersion yog qhov tshwj xeeb ntawm modal dispersion uas yog fiber ntau dispersion uas feem ntau cuam tshuam nrog ib hom fibers. Feem ntau, PMD tshwm sim thaum muaj ob hom uas ib txwm mus nrog tib lub nrawm vim muaj fiber ntau geometric thiab kev ntxhov siab symmetry uas taug kev ntawm qhov sib txawv ntawm qhov sib txawv vim qhov tsis zoo ntawm qhov tsis zoo uas tuaj yeem tawg qhov sib luag.
Chromatic Dispersion yog dab tsi?
Chromatic dispersion yog qhov tshwm sim los ntawm qhov sib txawv spectral Cheebtsam ntawm cov mem tes mus ncig ntawm qhov sib txawv. Ib qho chromatic dispersion tshwm sim feem ntau vim yog ob qho laj thawj. Raws li thawj qhov laj thawj, qhov ntsuas qhov cuam tshuam ntawm silica (silica yog cov khoom uas peb siv los ua cov fiber ntau optical), yog nyob ntawm qhov zaus ntawm lub teeb. Peb tuaj yeem hu nws cov khoom siv dispersion hauv chromatic dispersion.
Daim duab 02: Dispersive Prism
Qhov thib ob yog vim li cas lub waveguide dispersion. Lub teeb lub zog ntawm ib hom yog propagated ib nrab ntawm cov tub ntxhais thiab ib nrab ntawm cov cladding. Ntxiv mus, qhov Performance index ntawm ib hom yog nyob nruab nrab ntawm cov refractive indices ntawm cladding thiab cov tub ntxhais. Tus nqi tiag tiag ntawm qhov ua tau zoo yog nyob ntawm qhov kev faib ua feem ntawm lub zog uas muaj nyob rau hauv cladding thiab core. Yog hais tias feem ntau ntawm lub hwj chim yog nyob rau hauv lub hauv paus, qhov Performance index yuav los ze zog mus rau lub core refractive index. Yog hais tias feem ntau ntawm lub hwj chim nyob rau hauv lub cladding, ces qhov zoo Performance index yog ze rau lub cladding refractive index. Lub hwj chim faib ntawm ib hom ntawm cov tub ntxhais thiab cladding ntawm ib tug fiber ntau yog ib tug muaj nuj nqi ntawm lub wavelength ntawm lub teeb uas hla lub fiber. E.g. ntev lub wavelength, ntau zog nyob rau hauv lub cladding. Yog li ntawd, txawm tias tsis muaj cov khoom tawg, qhov kev ntsuas zoo ntawm cov qauv hloov thaum lub wavelength hloov, uas yog lub npe hu ua waveguide dispersion.
Qhov txawv ntawm Modal thiab Chromatic Dispersion yog dab tsi?
Modal thiab chromatic dispersion yog qhov tseem ceeb hauv kev piav qhia cov khoom siv kho qhov muag ntawm optical fibers. Modal dispersion yog ib hom kev distortion mechanism uas qhov distortion tshwm sim nyob rau hauv multimode fibers thiab lwm yam waveguides. Chromatic dispersion yog qhov tshwm sim los ntawm qhov sib txawv spectral Cheebtsam ntawm ib tug mem tes mus txawv tebchaws. Qhov sib txawv tseem ceeb ntawm modal thiab chromatic dispersion yog tias modal dispersion tuaj yeem tshwm sim nrog lub teeb ci monochromatic whereas chromatic dispersion tsis tuaj yeem tshwm sim nrog lub teeb ci monochromatic.
Summary – Modal vs Chromatic Dispersion
Modal thiab chromatic dispersion yog qhov tseem ceeb hauv kev piav qhia cov khoom siv kho qhov muag ntawm optical fibers. Qhov sib txawv tseem ceeb ntawm modal thiab chromatic dispersion yog tias modal dispersion tuaj yeem tshwm sim nrog lub teeb ci monochromatic whereas chromatic dispersion tsis tuaj yeem tshwm sim nrog lub teeb ci monochromatic.
