8th Sem Subject Ofc1st chapter notes by Lohith kumar 11GUEE6018

1. 2K6EC802: OPTICAL COMMUNICTION
Lectures: 4 Hours/Week Part-A | Chapter 1
Introduction: Evolution of fiber optic communication system. Advantages,
Basic optical laws and definitions. Mode theory for circular waveguides,
Single mode and Graded - index fiber
Structures 7 hours.
1st chapter related question and Answers
1. With help of a schematicdiagram explain the optical fiber
communication system?
2. Derive an expression for numerical aperture of the fiber?
3. Explain the common optical fiber cable structure?
4. With the Help of Snell’s law illustrate the phenomenon of Total internal
reflections?
5. The refractive index of glass 1.5 and that of air is 1.0. Calculate the critical
6. Whatis numerical aperture?Deduce an expression for the same?
7. Compare the following fibers.
 Single – Mode step index
 Multi – Mode step index
 Graded index and give the typical dimensions also.
8. Explain the concept of total internal reflection using snell’sLaw ?

2. 9. Calculate the critical angle given thatn1= 1.50 for glass and n2=1.00 for
10. Explain brieflydifferenttypes of optical fibers and their properties?
11. Define the following terms with figures
 Numerical aperture
 Acceptance angle
 Critical angle
 Step index refractive index profile
 Graded index refractive index profile
12. A step index fiber with a large core diameter compared with the
wavelength of transmitted light has an acceptance angle in air of 22˚ and
relative RI difference of 3%. Estimate the numerical aperture and the
critical angle at the core – cladding interface for the fiber.
13. Compare the optical communication with satellite communication?
14.A step fiber has a normalizedfrequency V=28 at1550nmwave length .if
the core radius is 25µm. find the numerical aperture. Alsocalculate the
number of modes M entering the fiber.
15. IIustratesnell’s law for a fiber with the refractive indexes of the core and
cladding 1.48and 1..46. Take one incidence angle each greater and lesser
than critical angle of incidence Φc for the illustration.
16. A step index fiber has a normalized frequency V=28ata 1550 nm wave
length. If the core radius is 25µm,findthe numerical aperture. Also
calculate the number of modes M entering the fiber.

3. 1. With help of a schematicdiagram explain the optical fiber
communication system?
Solution:

8. 3. Video
 Broad Cost T V
 Tv Mini Cameras
4.In Data Sharing and communication
 Computers
 Cpu to peripherals
 Cpu to Cpu
 Lans
 Aircrafts
 Satellite ground station
5. Sensors
 Hydrophone
 Position Temp pressuring and currentetc.

9. 2) Derive an expression for numerical aperture of the fiber?
Solution :

11. 3) Explain the common optical fiber cable structure?
Solution :

13. 4) With the Helpof Snell’s law illustrate the phenomenon of Total internal
reflections?
Or
8) Explain the concept of total internal reflection using snell’sLaw ?
Solution :

15. 5) What is numerical aperture?Deduce an expression for the same?
Solution :

17. 7. Compare the following fibers.
 Single – Mode step index
 Multi – Mode step index
 Graded index and give the typical dimensions also.
Solution : Pls attaché notes from Surya
11) Define Acceptance angle and Explain with diagram ?
Solution :

18. 13) Compare the optical communication with satellite communication?
Solution :
Optical Communication Satellite Communication
1 Transmission Media is
Optical Fiber cable
Transmission mediais airline
2 Carrier Bandwidth is 105 GHZ Carrier Bandwidth is 6 GHZ
3 Message signal is transmitted
in the lightwith carrier
Message signal is transmitted in the
electromagneticwith carrier
4 Low cost High Cost
5 It required to boost the signal Not required to boost the signal
6 FastCommunication Slow Communication
7 Immunity to interference No immunity to interference
8 High bandwidth Lower bandwidth