光纤通信-实验报告

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1、PHTN4661LabReportYuanWeiz5052230XiaoxueLiuz5047180Inthislab,weuseC++tosimulateasquarecorewaveguide・Weexplorethepropertiesandthefundamentalmodeofit.WeareprovidedsomeheaderfilesandamainfunctionunderC++language.AndalsotwoPDFfilestoindicatethethingsweshoulddoandtheprincipleso

2、fthelab.NowIamgoingtoanswerthequestionsonebyoneandexplainthestepsofthelab.PreambleFirstlyweareprovidedalibraryoffunctionscalledtheTightNumericalRecipes'(LNR)andafilecalled4square.dafwhichcontainstheparametersofawaveguide・Wedonotneedtochangethefile.Inpreamble,wejustrunthem

3、ainlxcfileandtypein"square.dat'toreadtheparametersofthewaveguide・AndthentheprogramshowstheEffectiveindexofit.Justlikethefollowingfigure.Tokeepthedisplayoftheresult,weadd“cin>>filename;，'atthebottom.Inputfile:square.datEffectiveindex：1.448342061Problem1Withthegivenformula,

4、wecancalculatetheVvalueeasilybycalculator.Herenco=1.450,ncl=1.447,p=5.When九=1.55,V=1.89andthewaveguideissingle-moded.WhenX=1.3,V=2.25andthewaveguideisnotsinglc-modcd.Thisresultmeansawaveguidecanbebothsingleormulti-modedwhenthewavelengtharedifferent・Problem2zy3031323334353

5、6373839404142Inthisstep,weonlychangethemiddlepartofthemain_l.eefileasfollowsofstreammyfileC^esults.txtn^ofstream::out);guide=Tiling_Read(filenam皂)；for(wl=1.2;wl<=1>6;wl=wl+0.02){solver=newFDM_Solv已厂(guide丿nxe，nxo，nye，nyo,wl);solver->Solve();cout<Effective

6、Index(0)<EffectiveIndex(0)<<}Wcusealooptocalculatethesomethingaswedidinpreamble.Theonlydifferenceisthatwecalculateaseriesofwavelengthandwritetheresultsinafilecalled4results.txtAndwegetresultsasfollow

7、1.21.4487911.221.44876.1.241.448744.261.4

8、4871：1.281.448691.31.44866!1.321.44863•1.341.448611.361.448581.381.448561.41.448531.421.44854.441.44848,1.461.44845.1.481.448431.51.44841.521.448384.541.448351.561.448334.581.44831Fromtheresults,wccanknowtheeffectiveindexateverywavelengthintherangeof1.6to12Andwefindthatwh

9、enwavelengthincreases,theeffectiveindexdecreases.1.44891.44811.448二宀空空佗二怕边怕Bjpppp.q叭旳qrHrKvirdrd