Optical Fiber Communication - Jun 2014

Electronics & Communication (Semester 7)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) List the advantages, disadvantages and applications of optical fibre communication system.(8 marks) 1 (b) A step index multimode fibre with a NA of 0.2 supports approximately 1000 modes at an 850 nm wavelength. What is the diameter of its core? How many modes does the fibre support at 1320 nm and at 1550 nm?(9 marks) 1 (c) Define acceptance angle and critical angle.(3 marks) 2 (a) Explain macro bending and micro bending losses with a neat diagram.(10 marks) 2 (b) Explain the signal distortion in fibres.(6 marks) 2 (c) Write a note on: i) Attenuation, ii) Absorption.(4 marks) 3 (a) List the desirable characteristics of the LED and LASER diode as optical source.(8 marks) 3 (b) Explain P-I-N photo-diode with a neat diagram.(8 marks) 3 (c) Photons of energy 1.53×-19 J are incident on a photo-diode which has responsibility of 0.65 A/W. If the optical power level is 10 μW, find the photo current generated.(4 marks) 4 (a) What is splicing? Explain the fusion splicing with a neat diagram.(8 marks) 4 (b) List the requirements of a good connector.(6 marks) 4 (c) Explain the fundamental types of misalignments between fibres.(6 marks) 5 (a) With a neat block diagram the digital signal transmission through an optical data link.(12 marks) 5 (b) Give the classification of front end amplifier used in optical fibre communication system. Explain any one of them.(8 marks) 6 (a) Explain the optical power loss model with a neat diagram.(10 marks) 6 (b) Clearly explain the analog link with the major noise contributions at each stage.(10 marks) 7 (a) What is WDM? Briefly explain the advantages of WDM.(4 marks) 7 (b) Explain the polarization independent isolator with a neat diagram.(8 marks) 7 (c) Write a note on MEMS technology.(8 marks) 8 (a) What are salient features of semiconductor optical amplifiers?(6 marks) 8 (b) Write note on:
i) SONET/SDH rings
ii) High speed light waveguide(14 marks)