Cochin University of Science and Techology (CUST) 2009-1st Year M.Sc Photonics and Bio- Photonics (FIVE NTEGRATED ) VI SEMESTER IN PHOTONICS, - Question Paper

IPH0.6109.01
M.Sc. DEGREE (FIVE YEAR INTEGRATED COURSE) VI SEMESTER exam IN
PHOTONICS, APRIL 2009
CEL 1601 OPTO ELECTRONICS
Time : three Hours
e)
What
Briefly
Explain
Describe
Discuss
Explain
Describe
Explain
Maximum Marks :
PART A
50
= 10)
(Answer ANY 5 questions)
(Each ques. carries 2 marks)
(5 x 2
is the effect of pressure on band gap of semiconductors.
discuss the velocity saturation in semiconductors.
excition absorption in semiconductors.
the structure of an edge emitting LED.
the operation of a linear electro-optic modulator.
the working of a phototransistor.
the mode locking technique in semiconductbr lasers.
the operational parameters of QCSE modulator.
PART — B
(Each ques. carries 8 marks)
(5 x eight = 40)
H A. a) What is the effect of heavy doping in semiconductors. (3)
b) Derive the expression for the total current density in semiconductors. (5)
. • OR
B. explain the density of states in quantum well.
At room temperature (300K) the effective density of sates in the valence
band is 2.66 x 10 25 M-3 for Si and seven x 10 24 M-3 for Gallium Arsenide. obtain the
(5)
corresponding effective masses of holes. (3)
III explain the different recombination processes of carries in semiconductors. (8)
OR
a) explain the effect of electric field on absorption in semiconductors. (4)
b) discuss quantum confined stark effect. (4)
IV A. discuss how can you achieve maximum external efficiency from an LED.
What is modulation bandwidth? compute the modulation bandwidth of
(5)
a GaAs based LED with r = 500ps. (3)
OR
B. discuss the performance of an LED with the help of its various electrical
and optical characteristics. (8)
V A. Mention the merits of hetrojunction lasers over homojunction lasers.
Write Port notes on:
1) Distributed feedback lasers
ii) Quantum well lasers (3)
OR
B. discuss the operating principles of a junction laser. (8)
VI A. a) discuss the basic principles of solar cells. (3)
b) explain the V-1 characteristics of solar cells. (5)
OR
B. a) explain the working of a PIN photodiode. (4)
b) Derive the expression for the external quantum efficiency. (4)
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