Download PTU Fiber Optics Overview_0 Question Bank

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1. What is optical Fiber
2. How optical fiber is better than coaxial copper cable (i.e. advantages of using optical fibers) - more data carrying capacity (band width, band width is proportional to frequency of carrier wave), more security, least electromagnetic interference (EMI).
3. Principle of working - Total Internal Reflection
4. Explain Total Internal Reflection
5. Composition/structure of optical fiber (discuss three layers core, clad and protective sheath along with materials i.e. glass or plastic)

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6. How light propagates through fiber - Explain qualitatively and show with the help of diagram.
7. Define acceptance angle, acceptance cone and numerical aperture. Find their mathematical expression/relation. Give physical significance of each.
8. What is A - fractional change in refractive index and express numerical aperture in terms of A.
9. What is mode?
10. Classification of optical fibers :
    1. Based on Index Profile of core -Step Index (SI) and Graded Index (GRIN). Plot the respective index profiles.

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    2. Based on number of modes - Single Mode Fiber (SMF) and Multimode Fiber (MMF)
11. What is V-no of fiber - V:@, where.a is core radius, A is wavelength of carrier wave; N.A. is numerical aperture of fiber. Cut off value of V is 2.405, if V<2.405, fiber is SMF and if V>2.405, fiber is MMF. Note that V-no of fiber is also known as Normalized frequency.
12. Various losses through fiber - absorption, scattering, material, bending, coupling loss etc.
13. Attenuation coefficient: a = (10/L)log(P_in/P_out), where L is length of fiber in km, P_in is input power launched into fiber and P_out is output power from the fiber. Units of a are dB/km.

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14. Joints in optical fibers - (i) Splice - permanent joint to increase the length of fiber - two types: mechanical splice n fusion splice (ii) Connector - semi-permanent/temporary joint to connect fiber with transmitter and/or receiver - can be of two types - mechanical (ferrule type) and extended beam connectors (iii) Coupler: device to split and/or combine optical signal from one port to many ports or many to one.
15. Applications of optical fibers - communication system, sensors.
16. Disadvantages of using optical fibers