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Seventh Semester B.E. Degree Examination, Dec.2013 tJan.2ll4,.., . Optical Fiber Gommunication ::

i{=.'fr[me: 3 hrs. Max. Marks:ioo"'.,. ..= Note: Answer FIVEfull questions, selecting ,..'',,,,,,

ni ,t,,* at least TWO questionsfrom eoch part. .'.. , ,,"..,,,,'

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E _., .. PART _ AE 1 a. Desq'ribe block diagram of an optical fiber transmission link and explain:the function of eachS element in link. (08 Marks)

E b. Explain*fut'is meant by graded index optical fiber using simpte.rfi*nlory concept indicate.- g the major advantages of this type of fiber with regard to multimodopropagation. loo naarrs;

$i c. A Graded index fiber with parabolic refractivelndex f,urnr: t.+g urjn, :1.46 if core6-:g i radius is 20 pm. Fhd,the number of modes at 1300nm and lf 50 nm. (06 Marks)Cgu

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.H+ 2 a. Describe Rayleigh Scatti"6ing in optical fiber. (06 Marks).E- ? uwou ruv r\oJ rvrEu ou4lllrldr.rB [r ulJtruar lluEr . i if4: ,:, (ub Marks)

E $ b. Briefly explain intramodal and intermodaldispersion. (06 Marks)E S ':"',,,1:\1f ':::t::' -,,t'tt'z'', ^1a2. \

; ! c. Consider a photodiode with quantum efficiency 75Ya, when photon of energy 1.6x10-roJ,S t are incident on the surface then calculate operating wavelength and it 2.6 pA photo currenta i through detector.coSr€sponding, determine incideni optical p-ower when deiector is operated5 S ^* -^*^ ,..^-.^r^--.L ^

F Pp / .) \; H c. Glass fiber exhibits materiar dispersion gir.; by, r'[ d-'rl

of 0.025. Determine materialtr'tro>9 A dispersion parameter at a wavelength of 0,85 pm and estimate rms pulse broadening / km for

; € good LED source with an rms spee+@id{h of 20 nm at this waveiength. (08 Marks)I

; € 3 a. Sketch and explain Fabry p.rq, ,.ronutor cavity of laser. (07 Marks)

$? b. Discuss rhe operation of ,itb.n RApD *itn n.ltad;;;. eTMarks)

: E c. Consider a photodiod,e;wi,ttri quantum efficiency i5%r-, when photon of energy 1.6x 10-te J.

E * at sarie wavebl$h.'--r ----- o' "''^-*'-l-r *^' svrvvrvr

lr;;;;ag.Eo8" I 4 a. Describg with aid of suitable diagram, three common techniqu" ,3tid6r,-"chanical splicing6 E of optical fibers. (06 Marks)< O l- rrr.rt, , r ^

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E * b. Wrltt aia of simple sketches, outline major categories of fiber "oupt..r.i E c. A. GaAs optical source that has a refractive index of 3.6 is closelycoupled to

U g b. WitE d of simple sketches, outline major categories of fiber couplers. CI6 Marks)- b c. .lil t aAs optlcal source that has a retracttve rndex of 3.6 is closely coupled to qtrp index fiber=ai ' 'ich has a core refractive index of 1.465, if the source size is smaller than'fibercore, andir* ".Wn-^'o " -^: .,"".::. uqDs vvrw rvuovlrvv lllLte.\ \Jr r.'ruJ, rr ttlg suututr slzg rs slllallcr tnan nDcFcorg, ano

*tWhatisthepowerlossindecibe1sfromsourceintofiber?@X,q#,"t'1=vEE :; > D a nrr! rI //-+-f

^ \Ll \PARr-B /{9"{ _orJh'\o{ E - n: n-.l c.i 5 a. Briefly d,iscuss the possible sources of noise in optical fiber receiffi..*,q[d )g,f;nnu.rrl.g b. Discuss how the eye diagram is powerful measurement tool fod\&stil[gttft da/#dandling2. capability in digital transmission system. \oL*- /r,6ilrvra*jE c. write a note on analog receivers. \Wt06 Marks)Ee'E 6 a. Explain the multi AM techniques employed in broadband analog application. (0E Nrarks)

b. Explain : (i) Microwave photonics (ii) RF over fiber. (06 Marks)c. Explain in brief : (i) Short wavelength band (ii) Chirping. (06 Marks)

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