Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 6th Sem New 2161005 Optical Communication Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VI (New) EXAMINATION ? WINTER 2019
Subject Code: 2161005 Date: 12/12/2019
Subject Name: Optical Communication
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Give the comparison of Step Index and Graded Index Fibers. 03
(b) Briefly Describe the block diagram of Optical Communication
Systems.
04
(c) A multimode step index fiber has a 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 1600.Calculate the
acceptance angle, numerical aperture and the diameter of the fiber
core.
07
Q.2 (a) Explain the significance of Carrier confinement related to the
optical source.
03
(b) A typical LED emits light at a center wavelength of 920nm with
??=20nm, Calculate the ?f.
04
(c) How does material dispersion occur in an optical fiber. Obtain the
expression for group delay ?mat resulting from the material
dispersion and from this, deduce the relation for the pulses spread
?mat in terms of material dispersion Dmat ( ?).
07
OR
(c) Define signal attenuation and how is it mathematically expressed.
Explain the Bending losses ( Micro bending losses, Macro
bending losses).
07
Q.3 (a) Mention difference between Electrical bandwidth and optical
bandwidth.
03
(b) ?The optical power launched into a fiber does not depend on the
wavelength of the source but only on it?s brightness? Justify.
04
(c) Briefly discuss the possible sources of noise in optical receivers. 07
OR
Q.3 (a) Mention difference between Indirect band gap material and direct
band gap material.
03
(b) What is equilibrium numerical aperture. Give the significance of
the same.
04
(c) Explain detection process in the p-n photodiode. Define the
quantum efficiency and responsivity of a photo detector.
07
Q.4 (a) Define with reference to eye diagram:
(1) Width of eye opening
(2) Timing jitter.
03
(b) Discuss optical power loss model for a point to point link. 04
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VI (New) EXAMINATION ? WINTER 2019
Subject Code: 2161005 Date: 12/12/2019
Subject Name: Optical Communication
Time: 02:30 PM TO 05:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Give the comparison of Step Index and Graded Index Fibers. 03
(b) Briefly Describe the block diagram of Optical Communication
Systems.
04
(c) A multimode step index fiber has a 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 1600.Calculate the
acceptance angle, numerical aperture and the diameter of the fiber
core.
07
Q.2 (a) Explain the significance of Carrier confinement related to the
optical source.
03
(b) A typical LED emits light at a center wavelength of 920nm with
??=20nm, Calculate the ?f.
04
(c) How does material dispersion occur in an optical fiber. Obtain the
expression for group delay ?mat resulting from the material
dispersion and from this, deduce the relation for the pulses spread
?mat in terms of material dispersion Dmat ( ?).
07
OR
(c) Define signal attenuation and how is it mathematically expressed.
Explain the Bending losses ( Micro bending losses, Macro
bending losses).
07
Q.3 (a) Mention difference between Electrical bandwidth and optical
bandwidth.
03
(b) ?The optical power launched into a fiber does not depend on the
wavelength of the source but only on it?s brightness? Justify.
04
(c) Briefly discuss the possible sources of noise in optical receivers. 07
OR
Q.3 (a) Mention difference between Indirect band gap material and direct
band gap material.
03
(b) What is equilibrium numerical aperture. Give the significance of
the same.
04
(c) Explain detection process in the p-n photodiode. Define the
quantum efficiency and responsivity of a photo detector.
07
Q.4 (a) Define with reference to eye diagram:
(1) Width of eye opening
(2) Timing jitter.
03
(b) Discuss optical power loss model for a point to point link. 04
2
(c) Explain the performance of passive linear bus and also prove that
optical power available at a particular node decreases with
increasing distance from source.
07
OR
Q.4 (a) Define Q factor for digital transmission through optical cable. 03
(b) Consider a 30-km long optical fiber that has an attenuation of 0.8
dB/km at 1300 nm. If 200 ?W of optical power is launched into the
fiber find out the optical output power Pout.
04
(c) Write short notes on Syncronous optical fiber networks(SONET). 07
Q.5 (a) Discuss the Cut back technique for attenuation measurement. 03
(b) Write short note on EDFA . 04
(c) For a 2x2 fiber coupler show that the phase of the driven fiber
always lags 90? behind the phase of the driving fiber. Also define
the following related to optical coupler: (1) splitting ration (2)
Excess loss (3) Insertion loss (4) Crosstalk
07
OR
Q.5 (a) Explain any one method for optical dispersion measurement. 03
(b) Write short note on Raman Amplifier. 04
(c) Explain Mach-Zehnder Interferometer (MZI) multiplexer in detail. 07
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This post was last modified on 20 February 2020