Download Model question papers & previous years question papers
|
Posted By: C.Agnes Member Level: Silver Posted Date: 17 Feb 2008
|
2007 Anna University B.E Electronics and Communication Optical Communication Question paper
|
|
|
B.E. / B.Tech. DEGREE EXAMINATION, NOVEMBER/ DECEMBER 2007
Seventh semester
(Regulation 2004)
Electronics and Communication Engineering
EC 1402 – OPTICAL COMMUNICATION
(Common to B.E. part time) sixth Semester Regulation 2005)
Answer all questions
PART A – (10*2=20marks)
1. Give the relationship between rays and modes.
2. A silica optical fiber has a core refractive index of 1.5 and a cladding refractive index of 1.47. Determine the angle of acceptance angle in air for the fiber.
3. What do you mean by polarization mode dispersion?
4. Distinguish dispersion shifted and dispersion flattened fibers.
5. What do you mean by heterojunction? Mention its advantages.
6. List the different types of mechanical misalignment that can occur between two joined fibers.
7. What are desired features of a photo detector?
8. Define quantum limit.
9. What are the advantages of WDM?
10. Distinguish fundamental and higher order solitons.
PART B – (5*16=80)
11. (a) (i) Explain with a neat diagram the elements of an optical fiber transmission link. (10)
(ii) A multimode step index fiber with a core diameter of 80 µm and a relative index of 1.5% is operating at a wavelength of 0.85µm. If the core refractive index is 1.48, estimate the normalized frequency for the fiber and the number of guided modes. (6)
Or
(b) (i) Discuss the evolution of fiber optic communication system. (6)
(ii) Sketch and explain the electrical field distribution of the lower order guided modes in symmetrical slab waveguide. (6)
(iii) Draw the structure of graded index and step index fibers with their typical dimensions. (6)
12. (a) (i) When the mean optical power launched into an 8km length of fiber is 120µW, the mean optical power at the fiber output is 3µW. Determine
(1) Over all signal attenuation in dB/Km and
(2) The overall signal attenuation for a 10km optical link using the same fiber with splices at 1km intervals, each giving an attenuation of 1dB. (6)
(ii) Explain with suitable diagrams the different mechanisms that contribute to attenuation in optical fibers. (10)
Or
(b) (i) Discuss in detail intramodal dispersion with relevant expressions and diagrams. (10)
(ii) Write a brief note on design optimization with relevant expressions and diagrams. (6)
13. (a) (i) Draw and explain the LED structures based Double Hetero structure configuration. (8)
(ii) Discuss the principles of operation of laser diodes. What are the effects of temperature on the performance of a laser diode? (8)
Or
(b) (i) Explain the different sensing schemes available to improve the power coupling efficiency. (8)
(ii) Explain the fiber splicing techniques with necessary diagrams. (8)
14. (a) (i) A silicon p-i-n photodiode incorporated into an optical receiver has a quantum efficiency of 60% at a wavelength of 0.9µm. The dark current is 3nA and load resistance is 4K?. The incident optical power is 200nw and the receiver bandwidth is 5MHz. Determine
(1) mean square quantum noise current
(2) mean square dark current and
(3) Mean square thermal noise current at a temperature of 200C. (8)
(ii) Draw and explain the operation of APD. (8)
Or
(b) (i)Discuss the different noise sources and disturbances in the optical pulse detection mechanism. (6)
(ii) Derive an expression for the bit error rate of an optical digital receiver. (10)
15. (a) Explain the significance of link power budget and rise time budget with one illustration for each. (16)
Or
(b) (i) Explain the principle of Erbium doped fiber amplifier. (10)
(ii) Give a brief account of the principles of SONET. (6)
Return to question paper search
|
|
|
Submit Previous Years University Question Papers and
make money from adsense revenue sharing program
Are you preparing for a university examination? Download model question papers
and practise before you write the exam.