Download PTU (Punjab Technical University) B.Tech (Bachelor of Technology) / BE (Bachelor of Engineering) 2021 January ECE 7th Sem 71911 Optical Communication Previous Question Paper
Total No. of Pages : 02
Total No. of Questions : 18
B.Tech. (ECE) (2012 to 2017) (Sem. ?7)
OPTICAL COMMUNICATION
Subject Code : BTEC-702
M.Code : 71911
Time : 3 Hrs. Max. Marks : 60
INST RUCT IONS T O CANDIDAT ES :
1 .
SECT ION-A is COMPULSORY cons is ting of TEN questions carrying TWO marks
each.
2 .
SECT ION-B c ontains F IVE questions c arrying FIVE marks eac h and s tud ents
have to atte mpt any FOUR q ues tions.
3 .
SECT ION-C contains THREE questions carrying T EN marks e ach and s tudents
have to atte mpt any T WO questio ns.
SECTION-A
Write briefly :
1.
What is the concept of pulse broadening?
2.
Explain briefly fiber coupling losses.
3.
How BER helps to determine receiver performance?
4.
Discuss the concept of negative resistance in APD photo-detector.
5.
Using Ray theory describes the mechanism for the propagation of light in an optical fiber.
6.
"Nonlinearities are related with intensity", Justify the statement.
7.
A graded index fiber has a parabolic refractive index profile with 45 m diameter. The
numerical aperture is 0.25. Find out the number of guided modes propagating when it is
operating at 1.5 m wavelength.
8.
Give details of optical cable construction.
9.
Draw diagram and explain briefly distributed feedback laser.
10. How frequency chirping effects the bandwidth?
1 | M C o d e - 7 1 9 1 1
( S 2 ) - 5 9 8
SECTION-B
11. A glass clad fiber is made with core glass of refractive index 1.5 and cladding is doped to
give a fractional index difference 0.0005. Calculate the cladding index and critical
internal reflection angle.
12. What do you understand by FWHM? How does it apply to LED's characteristics?
13. Differentiate the optical TDM system and code division multiplexing system.
14. A multimode step index fiber has a relative refractive index difference of 1 % and a core
refractive index of 1.5. The number of modes propagating at a wavelength of 1.3 m is
1100. Estimate the diameter of the fiber.
15. Discuss with the aid of a block diagram, the function of an optical fiber receiver in
communication with its components.
SECTION-C
16. Fiber to fiber coupling losses is affected by intrinsic and extrinsic coupling losses. Can
intrinsic coupling losses be limited by limiting fiber mismatches?
17. Outline structure of tunable semiconductor lasers for optical fiber communications
discussing their relative merits and drawbacks.
18. Explain the following mechanism associated within optical fiber communication :
a) Quantum shot noise
b) Avalanche excess noise
c) Fiber mode partition noise
d) Thermal noise
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any
page of Answer Sheet will lead to UMC against the Student.
2 | M C o d e - 7 1 9 1 1
( S 2 ) - 5 9 8
This post was last modified on 26 June 2021