OPTICAL FIBRE COMMUNICATION (OFC) MAY 2014 ELECTRONICS AND TELECOMMUNICATION SEMESTER 8
QP Code : MV-19218
(3 Hours) [Total Marks : 100]
N. B. : (1) Question No. 1 is Compulsory.
(2) Attempt any four questions out of remaining six questions.
(3) Assume suitable data wherever necessary and justify the same.
| 1. (a) | Compare dark current with optical current semiconductor. | 5 |
| (b) | Explain direct and Indirect band gap semiconductor. | 5 |
| (c) | What do you mean by optical waveguide? How it is different from Electrical | 5 |
| waveguide? | ||
| (d) | Explain Bandwidth distance product. | 5 |
2. (a) | Derive the expression for Numerical Aperture of a step -index fiber. What | 5 |
| will happen to Numerical Aperture if cladding is removed? | ||
| (b) | Compare step index and graded index fiber. | 5 |
| (c) | What do you understand by intramodal dispersion? Derive the expression | 10 |
| for material dispersion. | ||
3. (a) | Explain the significance of V-number. Derive the expression for number of | 10 |
| guided modes in graded index fiber. | ||
| (b) | Explain following terms: | 5 |
| (i) Total internal angle | ||
| (ii) Acceptance angle | ||
| (iii) Critical angle | ||
| (iv) Quantum efficiency | ||
| (v) Responsivity | ||
| (c) | State the difference between LED and LASER. | 5 |
4. (a) | Explain Modified Chemical Vapour Deposition (MCVD) method of fiber | 10 |
| fabrication? | ||
| (b) | Explain with neat skeches fiber splicing techniques. Enlist the desirable | 10 |
| requirements of a good connector. | ||
5. (a) | A photodiode has a quantum efficiency of 65% when a photon of energy | 10 |
 (i) At what wavelength is the photodiode operating. | ||
| (ii) Calculate the incident optical power required to obtain photo current | ||
| of 2.5 uA when the photodiode is operating as above. | ||
| (b) | Explain the various factors responsible for optical signal attenuation and | 10 |
| dispersion. | ||
6. (a) | With the help of reciver configuration circuit diagram, explain the working | 10 |
| of optical reciver. Also derive the expression for output. | ||
| (b) | Explain all aspects of link power budget. | 10 |
7. | Write short notes on (any four) | 20 |
| (i) Linearly polarized modes | ||
| (ii) OTDR | ||
| (iii) WDM | ||
| (iv) Compare PIN and APD diode | ||
| (v) Optical amplitiers |
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