Sri Balaji Technical Campus, JaipurBenad Road, Jaipur-302013

Facutly of Engineering

Course: B.Tech Semester: 8th

Subject Code & Name: 8EC3 & Optical Communication

Assignment No: 1 Due Date of Submission: 04/02/2014

Max. Marks:100

Objective Questions (1 to 20)Q1. Light is confined within the core of a simple optical fiber by

A) RefractionB) Total internal reflection at the outer edge of the claddingC) Total internal reflection at the core cladding boundary D) Reflection from the fiber’s plastic coating

Q2.What makes optical fibers immune to EMI?A) They transmit signals in as light rather than electric currentB) They are too small for magnetic fields to introduce current in themC) Magnetic field cannot penetrate the glass of the fiberD) They are readily shielded by outer conductors in cable

Q3. Which of the following is not a reason to use fiber-optics cables for point to point data transmission?

A) Need to assure data securityB) Avoidance of ground loopsC) Data-transfer rates too low to use metal cablesD) Elimination of spark hazards

Q4. Refractive index is defined as:A) C/VB) V/CC) C/DD) None of these

Q5. The highest data rate achieved in optical communication is ina) Tb/sb) Gb/sc) Mb/sd) Kb/s

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Q6. Which one is the optical source?a) LEDb) Laser diodec) Bothe the LED & Laser dioded) None of these

Q7. The wavelengths are used in optical fibers ina) Micrometersb) Centimetersc) Millimetersd) Kilometers

Q8. What do you mean by LED?a) Light emitting diodeb) Light emitting devicec) Low electron dioded) None of these

Q9. APD stands fora) Avalanche photo diodeb) Active photo diodec) Advanced phase dioded) None of these

Q10. As ray of light moves away from the center of a multi-mode, graded index fiber, which one of the following statements is true?

A. Light will be absorbed by the claddingB. Light will be Reflected by the claddingC. Velocity of the light will decreaseD. Velocity of the light will increase

Q11. Optical communication operates on the principle ofA. Total internal reflectionB. Tynall effectC. Photo electric effectD. Laser technology

Q12. Which is used as optical detector?a) APDb) LEDc) Laser dioded) Non of these

Q13. Snell’s law establishes a relationship betweena) Incident wave & refracted wave b) Incident wave & reflected wavec) Refracted wave & reflected waved) None of these

Q14. Total internal reflection occurs when incident angle isa) Equal to critical angleb) Greater than critical anglec) Less than critical angled) None of these

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Q15. Which one has greater refractive index?a) Coreb) Claddingc) Aird) None of these

Q16. Numerical aperture can be increased bya) Increasing the acceptance angleb) Decreasing the acceptance anglec) Decreasing the refractive index of claddingd) None of these

Q17. The V- number of a fiber isa) Normalized frequency parameterb) Normalized length parameterc) Attenuation constantd) Dispersion constant

Q18. Single mode fibers propagates a) Fundamental modeb) Higher order modec) Hybrid moded) None of these

Q19. For step index fiber, the number of modes can be calculated by the formulaA) V2/4B) V3/2C) V2/3D) V2/2

Q20. For graded index fiber having parabolic refractive index profile, the number of modes can be calculated by the formula

A) V2/4B) V3/2C) V2/3D) V2/2

Subjective Questions (21 to 25)Q21. What are the elements of a complete optical communication? Explain. Also compare optical communication with other communication systems.Q22. Explain light propagating mechanism in an optical waveguide. Also explain the presence of skew and meridional rays in such waveguides.Q23. Define the term “numerical aperture” of the fiber. On what factors does it dependent? How can it be maximized? Explain.Q24. 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 cladding refractive index of 1.47.Determine:

(a) The critical angle at the core-cladding interface.(b) The acceptance angle in air for the fiber.

Q25. Write short note on(a) Liquid Phase (Melting) method.(b) Vapour Phase Deposition method.

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