SKR Engineering College 2007 B.E Electronics & Tele-Communication Engineering OPTICAL COMMUNICATION ( EC433 ) - Question Paper

SKR ENGINEERING COLLEGE
DEPARTMENT OF ECE
MODEL examination

OPTICAL COMMUNICATION ( EC433 )
CLASS: IV ECE 1& 2 DATE: 14.10.06
SEM : VII DUR : three HRS
ans ALL ques..

PART A – (10 x two = 20 marks)

1. A point of light is 12cm 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. Write the expression for the refractive index in GI fiber.
3. Write the expression of the effective number of modes that are guided by a curved multimode fiber of radius ‘a’.
4. What are the causes of absorption?
5. Distinguish ranging from direct and indirect band gap material.
6. Define Responsivity.
7. A provided APD has a quantum efficiency of 65% at a wavelength of 900nm. If 0.5µm of optical power produces a multiplied photo current of 10µA. obtain the multiplication M.
8. What is meant by ‘bulk dark current’?
9. Write the concept of ‘soliton’.
10. An optical signal has lost of its power after traveling 3.5km of fiber. What is the loss in dB/km of this fiber?

PART B – (5 x 16 = 80 marks)

11. (a) explain the mode theory for a circular waveguide.

OR

(b)(i) explain the propagation of modes in SM fiber.(8)
(ii) Derive modal formula. (8)

12. (a) explain the pulse broadening in GI fiber.

OR
(b)(i)What is mean by waveguide dispersion? Derive its expression for the identical. (8)
(ii) discuss about the PMD. (6)
(iii) explain the mode coupling. (2)

13. (a)(i) What is meant by heterojunction? (2)
(ii) Derive the external quantum efficiency and power of an LED. (14)

OR

(b)(i) discuss optical feedback and laser oscillation. (6)
(ii) discuss the modes and threshold condition and derive. (10)

14. (a)(i) explain the requirements of an optical detector. (6)
(ii) discuss the principle of Avalanche photodiode. (10)

OR

(b)An InGaAs pin photodiode has the subsequent parameters at a wavelength of 1300nm: ID = four nA, ? = 0.9, RL = 3000O and the surface leakage current is negligible. The incident optical power is 300 nW (-35dBm), and the receiver bandwidth is 20 MHZ. obtain the different noise terms of the receiver.

15. (a)(i) explain the operational principle of WDM. (8)
(ii) discuss about the connector return loss. (8)

OR

(b)(i) discuss the link power budget of a fiber optic point to point link.(6)
(ii) discuss the rise time budget of a fiber optic point to point link. (10)



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