त 10000EC405122101 Pages: 2

Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

Seventh Semester B.Tech Degree Regular and Supplementary Examination December 2021 (2015 Scheme)

Course Code: EC405
Course Name: OPTICAL COMMUNICATION
Max. Marks: 100 Duration: 3 Hours
PARTA
Answer any two full questions, each carries 15 marks. Marks
1 a) Classify light wave systems based on the performance. (8)
b) List the different scattering losses in optical fiber. (3)

c) A silica optical fiber with a core diameter large enough to be considered by ray (4)
theory analysis has a core refractive index of 1.50 and a cladding refractive
index of 1.47.
Determine:
(a) the critical angle at the core—cladding interface
(b) the NA for the fiber
(c) the acceptance angle on air for the fiber.
2 a) What is intermodal Dispersion? How to modify the structure of the optical fiber (6)
so as to reduce intermodal dispersion.
b) Compare the performance of LED and laser diode. (5)
c) Draw the dispersion versus wavelength graph of dispersion shifted and (4)
dispersion flattened fibers.
3 ಖ Describe modified chemical vapour deposition method for the preparation of (8)
optical fibers
b) Write note on noise in laser diode. (4)
©) The energy difference between two states of a material 15 1074. Calculate the (3)
frequency of the electromagnetic wave emitted
PART छ
Answer any two full questions, each carries 15 marks.
4 ஐ Draw the structure and electric field distribution of RAPD. How is multiplication (6)
achieved in RAPD?

b) The quantum efficiency of silicon RAPD is 85% which is used for the detection (4)

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