· 5 a) What is meant by equilibrium Numerical aperture? Explain. [7] b) Describe the optical power launching from a light source to a fiber with necessary equations. [8] 6 a) Explain

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IV B.Tech I Semester Supplementary Examinations, Feb/Mar - 2015

OPTICAL COMMUNICATIONS

(Electronics and Communication Engineering)

Time: 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

*****

1 a) What are the various elements of an optical communication system? Explain

each element in brief. [7]

b) Define an optical fiber. Explain in detail different types of optical fibers with

neat sketches. [8]

2 a) Explain various fiber materials. [7]

b) Write about Scattering losses in an optical fiber. [8]

3 a) Discuss material dispersion and wave-guide dispersion. [8]

b) Explain information capacity determination and group delay with necessary

equations. [7]

4 a) Explain different splicing techniques. [8]

b) Derive the laser diode rate equation. [7]

5 a) What is meant by equilibrium Numerical aperture? Explain. [7]

b) Describe the optical power launching from a light source to a fiber with

necessary equations. [8]

6 a) Explain p-i-n photo detector with neat sketch. [8]

b) Explain how temperature effects on Avalanche gain in a p-i-n diode. [7]

7 How Rise-Time Budget analysis helps to determine dispersion limitation of an

optical fiber link? Explain. [15]

8 a) Explain the principle of optical attenuation meter with a neat diagram. [8]

b) Explain NRZ and RZ line codes in optical link with an example. [7]

Code No: R41041 Set No. 1 R10

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Time : 3 hours Max. Marks: 75



*****

1 a) Give the block diagram of a digital optical communication system and

explain the function of each block.

[8]

b) Write about mode coupling and V number.

[7]

2 a) Explain Signal distortion in optical fibers due to attenuation and absorption. [8]

b) Explain core and cladding losses in an optical fiber.

[7]

3 a) Explain polarization mode dispersion. [7]

b) Write about Intermodal and Intramodal dispersions.

[8]

4 a) Explain different Splicing techniques with neat sketch. [8]

b) Write about light source materials.

[7]

5 a) Give power coupling calculations of LED and Laser diode. [8]

b) Explain the power launching in optical sources.

[7]

6 a) Explain optical analog receiver with the help of a block diagram. [7]

b) Write about detector response time.

[8]

7 a) Explain considerations and component choice for optical system design. [7]

b) Explain various factors involving in overall optical system rise time.

[8]

8 a) Describe the eye pattern analysis for assessing the performance of a digital

fiber optical link.

[8]

b) What are the principles of the WDM technique? List various advantages? [7]


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*****

1 a) Write Advantages and Disadvantages of Optical Fibers Communication. [8]

b) A silica optical fiber with a core diameter large enough to be considered by ray

theory analysis has a core refractive index of 1.50 and a cladding refractive

index of 1.47. Determine: (a) the critical angle at the core–cladding interface;

(b) the NA for the fiber; (c) the acceptance angle in air for the fiber.

[7]

2 a) Explain Rayleigh scattering and Mie Scattering [8]

b) Write about cut off wavelength and mode field diameter of single mode fiber.

[7]

3 a) Explain connector return loss with a neat sketch. [7]

b) What is the difference between connector and splice? Describe various

connector types.

[8]

4 a) Discuss fiber alignments and joint loss in multimode and single mode fiber

joints.

[7]

b) Explain LED structures with neat sketch.

[8]

5 a) Explain the power coupling efficiency of a Laser diode. [8]

b) What is equilibrium numerical aperture? Explain the significance of

equilibrium numerical aperture.

[7]

6 a) Explain digital signal Transmission in optical detectors. [7]

b) What are different error sources in optical detector? Explain.

[8]

7 a) Explain about point-point links in Optical system design. [8]

b) Discuss rise time budget in an optical linkwith example.

[7]

8 a) Explain the method of measurement of chromatic dispersion in optical fibers. [8]

b) Explain Wavelength division multiplexing for optical communication system. [7]


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*****

1 a) Briefly explain the historical development of optical fiber communication. [7]

b) What is the significance of total internal reflection and numerical aperture of an

optical fiber?

[8]

2 a) Explain bending losses with neat sketch in an optical fiber. [7]

b) Explain Stimulated Brillouin scattering and Stimulated Raman scattering.

[8]

3 a) What is pulse broadening? Analyze pulse broadening in a graded index wave

guide.

[7]

b) Write about Butt Joint and Expanded Beam connectors.

[8]

4 a) Explain quantum efficiency and power of a LED. [8]

b) Write about Laser diode Modes and Threshold conditions.

[7]

5 a) Explain how power coupled from a vertical cavity surface emitter laser

diode to a single mode fiber.

[8]

b) Write short notes on radiation patterns of a Lambertian source with necessary

Equations.

[7]

6 a) Explain optical receiver and its configuration with a neat sketch. [8]

b) Write note on Probability of error and quantum limit in a optical receiver.

[7]

7 a) Discuss about the Point to Point Fiber Optic Link and its characteristics with

an example

[7]

b) Explain about link power budget with examples.

[8]

8 a) Explain WDM necessity in optical communication system. [7]

b) Discuss various line codes which are used in optical links. [8]


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Documents

· 5 a) What is meant by equilibrium Numerical aperture? Explain. [7] b) Describe the optical power launching from a light source to a fiber with necessary equations. [8] 6 a) Explain