SRM University 2007 B.Tech Electronics and Communications Engineering Bank : Microwave and Optical Communications - Question Paper

13. Sketch the structure, index profile and path taken by light ray in SI and GI fibers.
14. Why are single mode Lasers used for high speed communication.
15. What is Total Internal Reflection ? describe Critical Angle.
16. What is meant by leaky modes?
17. What are hybrid modes?
18. Compare MM and SM fibers
19. Define Normalized frequency.
20. How do scattering losses arise?
21. What is the cause for material dispersion?
22. What are Microbends?
23. What is waveguide dispersion?
24. Define Numerial aperture and provide the expression for the identical in both SI and GI fibres
25. What are the attenuation mechanisms in a fibre?
26. Differentiate Attenuation and Dispersion.
27. Differentiate step index and Graded index fibre.
28. A Continuous 12km long optical fibre link has a loss of 1.5db/km. What is the minimum optical power level that must be launched into the fibre to maintain an optical power level of 0.3?W at the receiving end?
29. The refractive index of a core is n1=1.48 nclad=1.46. Under what conditions will light be trapped inside the core?
30. For the plastic fibre, n1=1.495, n2=1.402. compute the acceptance angle and Numerical Aperture.
31. Distinguish Linear and Non-Linear scattering.
32. Distinguish intermodal and intramodal dispersion.
33. Explain how intermodal dispersion is decreased in GI fibre as compared to SI fibre.
34. What is MFD?
35. What is PMD?

Part-B
1. Explain with block diagram, the principles of optical fibre communication.
2. Discuss in detail about the construction, advantages and disadvantages of the SI and GI fibres.
3. Discuss in detail the attenuation mechanism in fibre.
4. Explain Mode Theory.
5. Discuss modal and material dispersions in SI and GI fibres.
6. Discuss in detail about the construction, advantages and disadvantages of the SM and MM fibres.
7. Explain briefly about the subsequent kinds of signal distortion by optical waveguides
i) Waveguide dispersion ii) Material Dispersion
8. Discuss on “Signal Distortion” in fibres.
9. Enumerate the characteristics of SM fibre.

Unit-IV – Optical Transmitter and Receiver
Part-A
1. Define double heterostructure. provide its significance.
2. What are the basic LED configurations being used for fibre optics?
3. What is lambertran pattern? Sketch it.
4. Define Quantum efficiency?
5. What is modes of cavity?
6. List the kinds and advantages of photodiode.

Earning:   Approval pending.