Roll No. .......................... 10tal No. of Questions: 08]

[Total No. of Pages: 02

M.Tech. OPTICAL COMMUNICATION SYSTEMS (Theory) SUBJECT CODE: EC - 507 Paper ID : [E0566] [Note: Please fillsubject code and paper ID on OMR]

Time: 03 Hours Instruction

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'1) 2)

Maximum Marks: 100

to Candidates: Attempt any Five questions. All questions carry equal marks.

(a) What is dispersion? List and explain types of dispersion. Evaluate the material dispersion parameter M. How the material dispersion parameter varies w~ththe w~velength. (b) In an optical fiber the power launched into an 8 km length of fiber is 12°J! W, the mean power received at the other end is 3 J! W. Find the .

overallsignalattenuationfor a 10km opticallink using samefiberwith splices at 1km intervals, each giving an attenuation. of 1 dB. Also evaluate numerical inp.ut/output power ratio.

Q2)

(a) Why stimulated ,emission is used in laser. Draw the structure ofDFB and FPA laser. Evaluate the wavelength spacing of output spectrum of laser and also illustrate the fundamental'structure of optical confining. (b) Calculate the quantum efficiency at 130Q rim. If the change in power of 2mW produces a curr~nt change of 6mA.

Q3)

(a) Consider a 5-channel FDM system having carriers at fl' f2 =' f] + ~, f3.~ f] + 2~, f4 = f] + 3 ~ and f5 = f] + 4~, whe~e ~ is the spacing between the carriers. On a frequency plot show tliat number and location of the triple beat and two-tone' third-order inter-modulation effects. (b) Prove that the limit for noise figure in an optical system is 3 dB.

Q4)

(a) Describe" the principle operation and type of SOA with diagrams. How the gain of SOA effects with different nonlinear effects present in SOA. (b) Calc~late the ASE power generated by TW SOA operating at 1300 nm with gain 30 dB. The bandwidth ofTW SOA is 40 illp.

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Q5)

(a) Suppose an APD has the following parameters: IL= 1 nA, tD,= lnA, n = 0.85, F = MI/2, RL = 103.Q and B = 1KHz. Consider a sinusoidat varying 850 nm signal, which has modulation index m = 0.85' and an average power level Po = - SOdBm, to fall on the detector at room .temperatu.re. Plot the SIN ratio as a function ofM for gains varying from 20 to 100. At what value ofM does the maximum SIN occurs?' (b) How photo detector noise effects SIN.

Q6) (a) Explain the best compensation technique for dispersion management. (b) Discuss the function and operating principle of fiber optical filter. Q7) (a) Explain principle ofWDM techriique?List the various active and passive components ofWDM. Explain MUX. DMUX and wavelength converters with suitable diagrams. (b) What do you mean by SCM? Explain schematic illustration of SCM. Q8) Write short note on following: (a) Soltions based communications. (b) Principle and Pumping wavelength ofEDF A.

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