Kurukshetra University 2010 B.Tech Optical communication - Question Paper

Optical communication
ECE-405E
&th semester KU

Roll No. .    Total Pages : 2

8713

BT-7/DX OPTICAL COMMUNICATION Paper : ECE~405(E)

Time : Three Hours]    [Maximum Marks : 100

Note : Attempt five questions in all, selecting at least one question from each unit.

UNIT-I

1.    Define critical angle for a dielectric interface and explain ' , phenomenon of total internal reflection in a step index

fibre.    10

WJhat do you mean by Acceptance angle? Calculate acceptance angle for a step index fibre having core refractive index 1.475 and cladding refractive index 1.465.    10

2.    Solve the wave equation in a cylindrical waveguide (optical fibre) and find out how it is convenient to use normalized frequency parameter V to discuss propagation of various modes of a waveguide.    20

UNIT-II

3.    (a) Discuss absorption mechanism near resonance frequency

in a material and give cause of absorption peak near 1.4 [im. .    10

What are the effects of bending in a fibre on strength of signals? Explain microbending in detail.    10

(of Give the origin of material dispersion in an optical fibre and discuss region of minimum material dispersion in it. 10

Discuss waveguide dispersion and justify why this dispersion is vital for a single mode fibre geometry to allow maximum transmission rate.    10

UNIT-III

5.    (a) Define internal quantum efficiency in LEDs and discuss

the four basic causes of optical loss in an LED, briefly.

10

(b) What is the pumping mechanism in a laser diode? Compare spectral characteristics of a laser diode and a LED.    10

6.    (a) Define Responsivity of a photodetector and explain its

importance. Why p-i-n photodiodes are widely used in yommuni cation?    10

Give the block diagram of the transmitter in optical fibre communication system and explain working of its various components.    10

UNIT-IV

7.    (a) How light is coupled from source to fibre in an optical

network? Discuss working of various couplers. 10

(b) Give a brief account of optical amplifiers and its use in optical communication network.    10

8.    (a) Discuss an example of Wide area network in the form

of several interconnects in form of multihop network v formation.    10

(b) What do you mean by a Photonic network? Discuss it as a future communication network alternative. 10

8713/2900/KD/2166

Attachment: kurukshetra-university-2010-b-tech-47831-1.pdf

Earning:   Approval pending.