Question Paper Mtech 1 Sem 2008

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M, Tech.in Optoelectronicsand Laser Technolory (First Semester)EXAMINATION, 2008

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PaperFourth OPTICAL COMMUNICATION

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Time : ThreeHours Max. Marks : 100

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) Note : Solveanyfive questionsin all, selectingonequestionfrom eachunit. UNIT - I

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Justifythat Attenuationin singlemodetlber is smallerthan in multimode fiber. Explain the mechanismthat causes attenuationin optical fiber. 10 OR

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Draw a basic-blockdiagramof Fiber optic communication link and explain in brief the function of eachbiock. Also explainthe needof fiber optical communication. 10

Discussthe nonlinearphenomenathat are most relevantfor fiber-optic communications.Define stimulatedfight and Brillouin scattering. 10 Describe group velocity Dispersion and inter-modal dispersionphenomenonin singlemode fiber. Discusshow doesGroup velocity Dispersionlimits the performanceof light wavesystemusedin opticalfiber system. 10

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Definethe corediameter of opticalfiber. Describethe types of opticalfiber giving fiber construction andrefractiveindex profile. Explainhow differentmodespropagates throughan' opticalfiber.Whataremicrobendsandmacrobends ? 10 Describethe followingprocessof fabricationof opticalfiber. (i) OVPO(outsidevapourPhauOxidation) (iD MCVD (Modifiedchemicalvapourdeposition) 10 Discussmeritsanddemeritsalso. OR Draw and explain ideal and real characteristicsof a WDM opticalfilter. Definethefollowingparameters10 (i) (ii) Centrefrequency PassBandwidth (iit (iv) StopBandwidth Isolation (v) Ripple.

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Describethe principai of operationof Erbium dopedfiber Amplifier.Discussits gainspectrum. 10 Discussthe advantagesand disadvantages of analog and disital modulationschemeusedin ooticalfiber svstems.1 0

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Discussthe designof optical Transmitterwith respectto followine(D Sourcefiber coupling (ii) Ddving circuitry (iii) Opticalmodulators 20 OR

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Define the following functionalparametersof optical passivq devices10 \., (t InsertionLoss(IL) (ii) RetumLoss(RL) (iii) Reflectance (i") Operatingwavelength (v) Transfermatrixfor a FiberopticBranchingDevice. UNIT - III

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OR Describe the principal of operation of Raman Amplifier. DefineRamanGainandBandwidth. 10 Discuss the purpose of use of optical ampliliers (Application)in the designof fiber opticcornmunication.10

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Discussthefollowingnoisegenerated in Receiver 10 (D ShortNoise (iD ThermalNoise Describethe following basicconceptscommonto all photo defectors10 (i) quantumefficiency Responsivity(ii) (iiD Bandwidth. IINIT - V

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Describe synchronousoptical Network (SONET) giving structure,BasicBuildingBlock andSTS-Nframes. 10 Describe the principal of operation of WDM optical switches. 10 OR

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Describe SynchronousDigital Hierarchy (SDH) giving standardbit ratesandfiame structure. 10 Describe the function WDM (wavelength division multiplexing) multiplexer andits channeiprofile type. 10

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M,Tech. in Optoeleclronicsand Laser Technology

UNIT _ IV

(First Semester) f,xamination,2008

Q.4. Describethe electrcnicstatcsin conjugatedmolecularsolids.How singlet and in molecular triplet statesare farmed.Discussfluorescence& phosphorescence solidswith the help ofsuitable diagram.

oE-l3 Paper Third OPTOELECTRONICS Time : ThreeHours

OR Max. Marks : 100

/,/Descdbeanyoneofthe followiugin detail(i) TIIF method (ii) Bossier Model

Note : Answer any five Questions.Selectingone from eachunit. All questionscarry equalmarks.

UNIT_V

UNIT - I i1.

What is relationbetweenabsorptionand emissionspectra? Describea rnethod for measurementofabsorption and Luminescencespecha.

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Describefabrication andworkingprincipleof organiclight emittingdiode.On whatfactorsdoestheefficiencvofOLED deoands. OR

OR Describethe processofelectron-holepair formation and rec,ombination in semiconductorswith suitablediasrams.

UNIT - II . Discussthenematic,Smecticaadcholosteric phases ofliquid crystals. Describethe operationoftwisted nematicdisplay. OR Describeany two ofthe following growth methodsofoptoelectronicmaterial and enumeratetheir advartages ard disadvantages (i) MBE

(ii) MocvD (iii) Plasma CVD UNIT _ III Q.| a/

Describe the principle c'f working chamcteristics and fabrication ol photodiode.Classifyphotodiode.

OR Write a short note on any two (i) Neno electronics (ii) Luminescentmaterials (iii) Solarcells.

Describein detailconstruction andprincipleofworkingoforganic photovoltaic. Discussfill factorVoc,IscandefficiencyofOPV.

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Code:S-739 M.Tech.in Optoelectronics& LaserTecblologr (First Semester)Examination,2008 QE- 12 Paper- Second (LASER TECHNOLOGY)

Time : ThreeHours

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,,1( Discussthe working principle ofrare earthdopedlasers.

Max Mark. 100

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Note - Attempt all five questions.Eachquestioncarry equalmarks.

OR a. What arestandingwaveandtravelling waveresonators? Discussary one activemodelocking scheme.

1. a. Why minimumthreeenergylevelsa:erequiredto causepopulationinversion betweentwo levels ?

b. How non-lineareffectsare usedfor enhanced modelocking? Discuss measmement techniques associated with ultrashorllaserpulses.

b. Explain purposeand working of optical resonators.Discussthe conditions for oscillator stabilitv in laserresonator.

Dir"u* th"o"""u"u4,u.d ,uffi3lt corditioosfo, laseractior.

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. Describein shortthe line broadeningmechanismof emittedlaserbeam. Out ofthese broadeningwhich one is the mostdominating? Unit - [ 2. a. Describetlle role ofmaroscopic polarizationon dispersionandgain in a laseroscillator.

Unit - V Explaintheappiicationoflaserin foilowirrg: a. Measurementof rotation b. Medicineandsurgery OR a. Describetheapplications oflasersin oplical- fibre communications. b. Explain the term holopaphyandholographicintenferomety.Discussapplicationofholographyin datastorage.

b. Explain designand analysisof any one popular optically pumpedsolid statelaserusingproperillustrations. OR the following topics in short : a. Q-switchingandmodelocking -,Explain b. Turablelaser

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,. Unit-N Explantrnportantcharacteristics ofultrashorlpulselasers.How ulfia short purselasersaregenerated /

b7 Discusssomeimpofiant applicationsof ultrashortpulse lasers.Explain / broadband coherentexcitationin short.

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,r" Explainhowpopulationinversionandlasingactionocculsin directbandgap semiconductors. Comparethe structureandpropertiesof semiconductor laserandlight emittingdiodes(LEDs;.

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Unit - I Describethe principle andstrucfl[e ofheterojunctionlasers.Discussimportantfactorsresponsiblefor lessesin heterojunctionlasers.Namesome importanthetedunctionlasermaterialsandtheir relativemerits. OR \

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M.Tech.jn Optoelectronicsand Laser Technology @irst Semester)EXAMINATION, 2008

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MODERN OPTICS tax. Marks: 100

Time : ThreeHou.t

carryequalmarks. Note: All questions / that determine theproperties .t. (7) Describethedifferentopticalcoeffrcients olthe medium at the macroscopic level.

*" reflectivity of silicon at 633 nm is 35% and the absorption coefficientis j.8 x t0-t m-1.Calculatethe tansmissionand optical densityof a samplewith a thicknessof 10 pm.

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OR Discuss in details about the Atomic oscillators & vibrational oscillators. \"/

and also Explain the excitation and relaxation in Photoluminescence explainPbotoluminescencespectroscopy. OR Defme Electroluminescenceand explair the principle and working of light emitting diodes.Give any two applicationsof LED's.

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Derive the expressionfor the elecfic field strength 6 , tle polarization i andthe electric displacementi anddefrnethem. OR Explain Quantumtra$ition ratesin detail. Discussthe physical origin of optical nonlinearitiesandexplainthe nonlinearfrequencymixing. Also explainthe non resona.ntard resonartnonlineadties.

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DiscussRayleigh, Brillouin and Ramanscatteriryincluding non-linear effects. Wrile shortnoteson (a) Fourier transform (b) Spatialandtemporalcoherence OR Wlat is Holography?DiscussHolographictecbniques& applications.