Anna University Chennai 2005 B.E Electronics & Tele-Communication Engineering ./B.TECH :OPTICAL COMMUNICATION - Question Paper

B.E./B.TECH.DEGREE exam NOV/DEC 2005
VII -SEMESTER
OPTICAL COMMUNICATION

TIME :3 hrs
MAX MARKS :100


PART -A (10 X two = 20 MARKS)


1. A point sorce of ligth is 12 cm beneath the surface of a large body of water (n = 1.33). What is the radius of the largest circle on the water surface through which the light can emerge?

2. Consider a parabolic index waveguide with n1 =1.75 ,n2 = 1.677 and core radius 25 micro meter. compute the numerical aperture at the axis and at a point 20 micro meter from the axis

3. Write the expression for the effective number of modes guided by a curved multimode fiber of radius 'a'

4. describe normalized propagation constant.

5. Draw the 3 key transistion process involved in laser action

6. Write the concept of indirect bandgap semiconductor materials

7. describe responsivity of photodiode.

8. describe quantum efficiency of a photodetector

9. List the sysyem requirements neede in analyzing a point -to- point link

10. Write the concept of solition

PART - B (5 X 16 =80)

11(i) Diacuss the signal distortion in single mode fibers

(ii) explain pulse broadening in graded index fibers with necessary equations

12(a) (i) Briefly discuss the evolution of fiber optic system

(ii) Compare the configuration of various kinds of fibers .
OR
(b)(i) Derive modal formula

(ii) explain the modes in step- index fibers

13(a) Draw the structures of edge-emitting LED and surface emitting LED and discuss the operation
OR
(b) (i)Discuss the LASER diode principle , modes and threshold conditions

14(a) Draw the schematics of pin photodiode and APD and discuss.
OR
(b) discuss the fundamental receiver operation in optical communication

15(a) discuss different kinds of fiber splicing techniques and fiber connectors
OR
(b) (i) discuss the operational principles of WDM

(ii) discuss the rise-time budget.

Earning:   Approval pending.