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S.R.M. University
Faculty of Engineering and Technology
School of Electrical and Electronics Engineering
Department of Telecommunication Engineering
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Question Bank
ET454
Optical Networks (Elective)
IV Year B.Tech. (ETE)
Unit – I – Fiber and Network Components
Part – A
1. Draw a block diagram of a fiber communication system.
2. Why fiber-optic communication is considered as the backbone of modern
telecommunications?
3. What are the advantages of fiber optic communication?
4. What are the disadvantages of fiber optic communication?
5. Define the term wavelength and frequency.
6. Define the term refractive index.
7. Describe the functions of core and cladding in an optical fiber. Why are their
refractive index is different? Which one has to be greater and why?
8. List the advantages of fiber optic communications over the types of
communication technologies.
9. Why is it necessary to meet the total internal reflection requirement inside an optic
fiber?
10. What is an acceptance angle? Why do we need to know what this angle is?
11. What is attenuation in an optical fiber? What is loss in an optical fiber?
12. List the major causes of attenuation in an optical fiber and explain their
mechanisms.
13. What is chromatic dispersion?
14. What are bandwidth and bit rate in communication systems?
15. What is the difference between dispersion and distortion?
16. Define Bandwidth. Why are electrical and optical bandwidths are different?
17. What is the relation between bit rate and bandwidth.
18. What does the term ‘State of Polarization’, mean?
19. What is Four Wave Mixing?
20. Why FWM is so important in today’s optical network?
21. What is WDM
22. What are the components used in an optical network?
23. What is the function of an optical amplifier?
24. What are three functional types of optical amplifier?
25. What is Crosstalk in SOA?
26. What are the two major mechanism that cause crosstalk?
27. What is amplified spontaneous emission?
28. Why is erbium used in EDFA?
29. What phenomenon determines the bandwidth of an EDFA
30. What is the function of coupler?
31. Name and describe two major classes of filters
32. What are the basic characteristics of a filter?
33. Give examples of reciprocal and nonreciprocal devices
34. Explain the function of circulators and isolators.
PART B
1. List the major Causes of Attenuation in an optical fiber & explain their mechanism
2. Explain in detail about light propagation in a fiber?
3. List three major causes of dispersion in an optical fiber & Explain their mechanism
4. Explain the principle of operation of a semiconductor optical amplifier (SOA)?
5. Show the structure of an EDFA & Explain the function of each component
6. Explain how stimulation emission occurs in an EDFA
7. Explain the function & the principle of operation of an isolator with neat diagram .
8. Explain the function & the principle of operation of a circulator?
9. List the types of switches and explain in detail any two switches?
10. Explain the function of Large optical switches and list them.
11. Compare the different types of large switches.
12. Explain the principle of operation of Fabry Perot (FP) filter?
13. Explain the principle of operation of Mach Zehnder Interferometer (MZI)?
14. Explain the function & the Principle of operation of Wavelength Converters?
UNIT II - Modulation, Demodulation & Design Consideration
PART A
1.
2.
3.
4.
5.
6.
Define Optical Sources
Show the diagram of fiber optic communication system
Draw the block diagram of Optical Transmitter?
Draw the block diagram of Optical Receiver
What are the advantages of optical fiber?
What are the major advantages of hetrostructured LED over a homostructured
one?
7. What is the difference between a surface emitting LED (SLED) & Edge emitting
LED (ELED)
8. What light source is called Lumberton?
9. Distinguish between Laser and LCD Sources
10. What are the characteristics of LASER diode?
11. What are the advantages of photo detector used as light source in fiber optic
communication system?
12. Define Intensity Modulation?
13. Define direct detection?
14. What is the function of coherent detection
15. Write the function of optical preamplifier.
16. What are the two methods of modulation/demodulation techniques used today in
fiber optic communication system?
17. Define Sub Carrier modulation?
18. Define Sub Carrier Multiplexing?
19. What is the application of Sub carrier Multiplexing (SCM)?
20. Define Receiver sensitivity?
PART B
1. Draw the basic block diagram of an optical communication link and explain the
function of the various parts
2. Discuss on the principal of light transmission in a fiber
3. Draw the electric circuit of an LED & Explain the function of each component?
4. Explain in detail the operation of LASER
5. What are the different light sources available? Explain any one of them
6. Write short notes on i) Surface emitting LED
ii) Edge emitting LED
7. Explain about Coherent optic system With block diagram
8. Write short notes on
UNIT III - 1G Optical Networks
PART A
1. What does the acronym SONET stand for? What is the SONET?
2. Define SONET/SDH?
3. What are the benefits of using SONET/SDH system?
4. Define SONET Multiplexing?
5. What are the elements used in SONET/SDH system?
6. Draw the block diagram of SONET infrastructure
7. What topologies and components are used in SONET network?
8. Why a ring topology is considered reliable?
9. What are the different computer interconnects.
10. Define MAN?
11. Draw the functional block diagram of SONET/SDH system?
12. Define STS-1 Signal?
13. Define OC-N signal?
14. What is meant by saying an overhead and payload are in frame format for
transmitted data?
15. Define overhead?
16. Define synchronous payload envelope (SPE)?
17. What is the function of SPE?
18. What is the data rate of STS-1 Signal?
19. Name the SONET layers
20. Define SONET physical layer?
21. What is the function of section layer?
22. What is the function of line layer?
23. Define path layer?
24. Draw the block diagram for ATM over SONET
25. Draw the block diagram for IP over ATM
26. Draw the block diagram for IP over ATM over SONET
27. Define Add/Drop Multiplexer?
28. Define WDM?
29. Why do we need to develop WDM fiber optic network?
30. Why is WDM the major trend in Fiber optic network?
PART B
1.
2.
3.
4.
5.
6.
Explain the functional block diagram of the SONET/SDH Multiplexing?
Briefly describe the functions, service of the SONET layer
Explain the elements of SONET/SDH infrastructure?
Explain in detail the computer interconnects.
Explain in detail about Metropolitan Area Network
Explain in detail the layered architecture.
UNIT IV - Broadcast And Select Networks
PART A
1.
2.
3.
4.
5.
Define Topologies?
Define Broadcast and select Network?
Define Broadcast and select single hop network?
Define Multihop network?
What are the characteristics of single hop network? What are the types of
topologies used in data communication network?
6. Draw the block diagram of the broadcast and select WDM network?
7. What are the topologies used in broadcast network and select network?
8. Define an N*N star coupler?
9. What is need for passive star topology?
10. Define: Bus topology & Tree topology?
11. What is the Difference between passive star topology and linear bus topology?
12. What are the characteristics used in single hop network?
13. What is the difference between single hop system and multihop system?
14. Define MAC protocol?
15. What is meant by synchronization?
16. Define Slotted ALOHA?
17. Why do cable network operators are interested in new architecture(such as FTTC,
FTTH)
18. Define FTTC
19. How does access network provide broadband access from the customers premises
to the edge network?
20. Give some applications of broadcast and select technique
PART B
1. Explain the topologies of broadcast networks
2. Explain the Broadcast and select single hop network?
3.
4.
5.
6.
7.
8.
9.
Explain the Broadcast and select multihop network?
Explain the characteristics of single hop network?
Explain the elements of optical access network architecture?
Describe Slotted ALOHA protocol?
Explain the future access networks
Explain about MAC Protocol
Short notes on: i) FTTC & FTTH
ii) ISDN & HFC
UNIT V - Wavelength Routed Networks & Optical TDM and CDM Networks
PART A
1. What are the two disadvantages of broadcast & select networks when its used in
WAN
2. Which fiber optic networks belong to the first generation &which one belongs to
the second generation? Give E.g.
3. What are the advantages of wavelength routed network?
4. Why do we need Optical Cross Connect (OCC)?
5. How to measure the benefits of wavelength conversion?
6. Why do we need an optical layer?
7. What services does an optical layer provide to the layer above?
8. Describe the optical layer service termed “establishing light path”
9. Describe the optical layer service termed “establishing virtual circuits”
10. Show the layered structure of fiber optic network , including the optical layer
11. Define OTDM?
12. Define Spread Spectrum?
13. What are spread spectrum techniques used CDMA?
14. Define Frequency Hopping Spread Spectrum?
15. Define Direct Sequence Spread Spectrum?
PART B
1.
2.
3.
4.
5.
6.
Explain OFDM
Explain detail the OTDM.
Explain Optical Cross Connect
Explain OCDMA network
Explain Spread Spectrum techniques?
Show the layered structure of fiber optic network & Describe their major functions