OPTICAL FIBRE COMMUNICATION (OFC), B.E. Electronics & Telecommunication, Semester 8, May 2009.

OPTICAL FIBRE COMMUNICATION (OFC),

B.E. Electronics & Telecommunication,

Semester 8, May 2009.

Con. 3142-09

(REVISED COURSE)

VR-4272

(3 Hours)

[Total Mark: 100]

N.B. (1) Question No 1 is compulsory.

(2) Answer any four questions out of remaining six questions.

1. Answer the following in brief:-

(a) Discuss the basic block diagram of optical communication system. ---- (5 Marks)

(b) What are direct and indirect semiconductors? Which types are suitable to be used as optical sources and detectors? ---- (5 Marks)

(c) How does the optical signal propagate through the GIF. ---- (5 Marks)

(d) What is the difference between coherent and non-coherent optical transmission? ---- (5 Marks)

2. (a) Explain the 'Different Modes' that can be supported by an optical fiber.---- (10 Marks)

(b) Using simple ray theory concept, discuss the transmission of light through single Mode fiber. What is the major advantage of this type of fiber? ---- (10 Marks)

3. (a) 'Optical signal distortion limits the information carrying capacity of the fiber' Justify the comment. ---- (10 Marks)

(b) List the important factors responsible for power loss in optical fiber. Explain each Factor briefly. ---- (10 Marks)

4. (a) What are the general requirements of a good optical source? Describe the technique used to give both electrical and optical confinement in injection lasers. ---- (10 Marks)

(b) Draw the structure of APD along with electrical field profile that exist in the various regions. Explain its working and also explain why it is also called RAPD. ---- (10 Marks)

5. (a) Describe two methods of splicing individual fibers together. What are some advantages and disadvantages of each method? ----- (10 Marks)

(b) Discuss a popular non-destructive technique for attenuation measurement. ---- (10Marks)

6. Describe three methods of preform fabrication. Include starting materials, heat sources, fabrication temperatures used and the technique used to make the preform for-each method. ---- (20 Marks)

7. Write short notes on any four:----- (20 Marks)

(a) Rise time budget

(b) Measurement of dispersion

(c) Radiative losses in optical fiber.

(d) PIN diode

(e) Double heterogenous LED.