《光通信技术》课件：Lecture2 Fiber-Optic Communications Technology

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1、tDJHtBEBD/0222222()22222()(),(:,:,:)()(),0(,)(,),(,)(,)0()(),integjtztzzzzEEEJE DE BHconductivitypermitivitypermeablityEEEBEtttEx y z tEx y eeEx yh Ex ymnhm nab 00erscos(/)cos(/)sin(/)sin(/)zzHHmxanybEEmxanybDetermined by boundary conditionApply to z-component2222222222222zzxzzyzzxzzyxyEHjExyhhEHjEy

2、xhhEHjHyxhhEHjHxyhhwherehkkk 12345612341234cossincossinFor the wave traveling in-direction:cossincossinSimilarly for the magnetic field,cossincossinzzzxxyyzzxxyyzxxyyEck xck xck yck yc ec ezEAk xAk xAk yAk y eHBk xBk xBk yBk y ez,axE,byEzz0at 00at 0,axE,byEyx0at 00at 0h2 h2=TE and TM FieldFor TM mod

3、es,l=0 and m=0 are not possible,TM11 is the lowest TM mode.()22(,),(,)(,)0zjtzzzzzEEx y eeEx yh Ex y222()()mnab 22222When then 0 11or 2ccmnjabmnfab222When mnab 222When mnab 221/2()()2ccmnfab22221ffbnamcmztjmmmmmmztjmmmmmmmerVAtzrHAtzrHerUAtzrEAtzrE)()(),(),(),(),(),(),(1,2,3.m ),()(ztjmmerU),(rUmknk

4、nm12)(kncm2)(22221sin2nniNA222221annaVa:radius of the core,is the optical free space wavelength,are the refractive indices of the core&cladding.c/n2c/n1minmaxGuided modesNo modesLeaky&radiationVPPtotalclad3222/)2(anV,2/)(,21nnna2/)2(Vancchromaltotalttt2mod2cnkmnsLt/)()/(/1jjpjn220221)(2222220221)(dc

5、badAnjjjjjpjk46m13b697.93428b39.8961612b50.01050294b20.11624142b40.007290464b10.06840432a60.8663412a30.8774794a50.4203993a20.4079426a40.7083952a10.6961663Germania Oxide 6.3%Silicon OxideOptical Fiber Refractive Index CalculationThis calculation utilizes Sellmeier equation and uses three-pole fitting

6、 for both SiCl4 and GeCl4.b39.8961612b697.93428m13k46f1 mam22bmf2 kak22bkn1 1f1 n2 1f2 1231.41.45n1()n2()n1 0.6328()1.457Model:Three-pole 4)/)(34002SkmnmpsD21502)(662)(286.14)(modppkmMHzalBW)/(314/)(,)(09.0)(104)(400225SDDDkmMHzBWmaterialc3 105109Dm()Unit:ps/(nm*km)Dm1 c2n1 dd2Dm2 c2n2 dd21.11.21.31

7、.41.5402002040Dm1()Dm2()Intermodal bandwidth for GI fiber10.01p134120.019p1341BW1 14.6128p2661p 2150 12BW2 14.6228p2662p 2150 2213401340.513411341.51342050001104BW1()BW2()Fresnel formulas,reflectances and transmittancesn11.5n21cacos1n2n12c18041.81Critical angle for total internal reflection p n22cos

8、n1n22n12sin2n22cosn1n22n12sin2 s n1 n2cosn2n22n12sin2n1 n2cosn2n22n12sin2Rp p 20 0.021.7Rs s 20102030405000.51Rp()Rs()180Phase shift v.s.incidence anglep 2180atann1n2n1n22sin21n1n2coss 2180atann1n22sin21n1n2cos405060708090050100150p()s()18013401340.513411341.51342050001104BW1()BW2()Material(Intramodal)bandwidth(62.5/125)S00.09101340D S04043DD D dd1122BW11 41051D 20.091 DD 2BW12 41052D 20.092 DD 21330133513401345135013550510611071.5107BW11()BW12()