光钎通信作业合集.pdf

《光钎通信作业合集.pdf》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、1.1Areceiverrequires10mWasinputpower.Ifallthesystemlossesaddupto50dB,thenhowmuchpowerisrequiredfromthesource?m1.2Thereare1010photonspersecondincidentonaphotodetectoratwavelength0.8,Computerthepowerincidentonthedetector.Ifthisdetectorconvertslighttocurrentata

2、rateof0.65mA/mW,whatcurrentisproduced?1.3Thepowerincidentonadetectoroflightis100nW.(a)Determinethenumberofphotonspersecondincidentonthedetectorifthewavelengthis800nm.(b)Repeatthecalculationifthewavelengthis1550nm.(c)Whichwavelengthrequiresthemostphotonstoprod

3、ucethe100nWofpower?1.4Tooperateproperly,afiberopticreceiverrequires-34dBmpower.Thesystemlossestotal31dBfromthelightsourcetothereceiver.Howmuchpowerdoesthelightsourceemit(inmW)？2.1Auniformcollimatedbeamisfocusedbyalenswhosefocallengthis20mmandwhose0.8mdiamete

4、ris10mm.Thewavelengthis.Computethefocusedspotsize.0.8m2.2ComputethedivergenceangleofaGaussianbeamofwavelengthandspotsize1mm.Ifthisbeamisaimedatthemoon,whatisthespotsizeonthemoon’ssurface?(Thedistance8betweentheearthandthemoonis3.810m)3.1Forsilica,computethe

5、magnitudeofthepulsespreadperunitlengthifthesourcewavelength0.85mis.Thespectralwidthis30nm.Repeatforaspectralwidthof2nm.(Supposethe0.85m90psnmkmdispersionatisabout)zEEesin(tkz)3.2Iftheattenuationcoefficient()forthewaveintheEqo51hasthevalue210cm,comp

6、utethepowerlossindBfor1km.Ifthelossinamediumis0.2dB/km,thenfindtheattenuationcoefficient.3.3Considersolitonpulseshavingapulsewidthof20psatthetransmitter,theypropagateinasinglemodefiberatawavelengthof1550nmwithnopulsedistortion.Ifthedispersionis2psnmkm.a)What

7、isthemaximumdataratethatcanbetransmittedbyusingthesesolitonpulses.b)Whatwilllimitthelengthoffiberoverwhichthisdatacanbetransmitted.5.1ConsideraSIfiberwithn11.5andn1.4852at0.82m.Ifthecoreradiusis50m,1.2mhowmanymodescanpropagate?Repeatifthewavelengthischan

8、gedto.n1.48n1.465.2Forasingle-modeandamultimodeGRINfiber,1and2,wavelength=0.82m,linewidth=20nm.(a)Computethe3-dBbandwidth-lengthproduct.Neglectwaveguidedispersion.(b)Repeatiflinewidth=