Optical Fibre Communication MCQ Unit -2

   Optical Fiber Communication

Note: Answer of questions are in bold options

UNIT -2

1.   Which of the following statements best explain the concept of material absorption?

  a)  A loss mechanism related to the material composition and fabrication of fiber.

b)  A transmission loss for optical fibers.

c)  Results in attenuation of transmitted light.

d)  Causes of transfer of optical power

 

2.   Absorption losses due to atomic defects mainly include-

a)  Radiation

b)  Missing molecules, oxygen defects in glass

c)  Impurities in fiber material

d)  Interaction with other components of core

 

3.   How the potential macro bending losses can be reduced in case of multimode fiber?

a)  By designing fibers with large relative refractive index differences

b)  By maintaining direction of propagation

c)   By reducing the bend

a) By operating at larger wavelengths

 

4.     Rayleigh scattering and Mie scattering are the types of

a)  Linear scattering losses

b)  Non-linear scattering losses

c)   Fiber bends losses

d)  Splicing losses

 

 

5.   The scattering resulting from fiber imperfections like core-cladding RI differences, diameter fluctuations, strains, and bubbles is

a)    Rayleigh scattering

b)    Mie scattering

c)    Stimulated Brillouin scattering

d)    Stimulated Raman scattering

 

6.   Raman and Brillouin scattering are usually observed at

a)  Low optical power densities

b)  Medium optical power densities

  c)  High optical power densities

d)  Threshold power densities

 

7.   What is dispersion in optical fiber communication?

a)   Compression of light pulses

b)  broadening of transmitted light pulses along the channel

c)   Overlapping of light pulses on compression

d)   Absorption of light pulses

 

8.   For no overlapping of light pulses down on an optical fiber link, the digital bit rate BT must be:

a)  Less than the reciprocal of broadened pulse duration

b)  More than the reciprocal of broadened pulse duration

c)   Same as that of than the reciprocal of broadened pulse duration

d)  Negligible

 

9.   Intermodal dispersion occurring in a large amount in multimode step index fiber results in

a)  Propagation of the fiber

b)  Propagating through the fiber

c)  Pulse broadening at output

d)  Attenuation of waves

 

10.   The index profile of a core of multimode graded index fiber is given by- a) N (r) = n1 [1 – 2Δ(r²/a)²]^1/2; r<a

b) N (r) = n1 [3 – 2Δ(r²/a)²]^1/2; r<a

c) N (r) = n1 [5 – 2Δ(r²/a)²]^1/2; r>a

d) N (r) = n1 [1 – 2Δ(r²/a)²]^1/2; r<a

 

 

11.   Disturbance along the fiber such as vibrations, discontinuities, connectors, splices, source/detectors coupling result in

a)  Modal noise

b)  Inter-symbol interference

c)   Infrared interference

d)  Pulse broadening

 

12.   Dispersion-shifted single mode fibers are created by

a)  Increasing fiber core diameter and decreasing fractional index difference

b)  Decreasing fiber core diameter and decreasing fractional index difference

   c)  Decreasing fiber core diameter and increasing fractional index difference

d)  Increasing fiber core diameter and increasing fractional index difference

 

13.   The fibers which relax the spectral requirements for optical sources and allow flexible wavelength division multiplying are known as-

a)  Dispersion-flattened single mode fiber

b)  Dispersion-enhanced single mode fiber

c)   Dispersion-compressed single mode fiber

d)  Dispersion-standardized single mode fiber

 

14.     The variant of non-zero-dispersion-shifted fiber is called as

a)   Dispersion flattened fiber

b)   Zero-dispersion fiber

c)   Positive-dispersion fiber

d)  Negative-dispersion fiber

 

15.   The optical source used for detection of optical signal is

a)  IR sensors

b)  Photodiodes

c)  Zener diodes

d)  Transistors

 

16.     An optical fiber behaves as a birefringence medium due to differences in

a)  Effective R-I and core geometry

b)  Core-cladding symmetry

c)   Transmission/propagation time of waves

d)  Refractive indices of glass and silica

17.   How many categories of nonlinear effects are seen in optical fibers?

a)   One

b)  Two

c)   Three

d)   Four

 

18.   Which thing is more dominant in making a fiber function as bidirectional optical amplifier?

a)  Core material

b)  Pump source

c)  Cladding material

d)  Diameter of fiber

 

19.   Self-phase modulation can be used for

a)  Enhancing the core diameter

b)  Wavelength shifting

c)  Decreasing the attenuation

d)  Reducing the losses in the fiber

 

20.   What is different in case of cross-phase modulation from self-phase modulation?

a)   Overlapping but same pulses

b)  Overlapping but distinguishable pulses

c)   Non-overlapping and same pulses

d)   Non-overlapping but distinguishable pulses