Question 1

If the input power 100?W is launched into 6 km of fiber, the mean optical power at the fiber output is 2?W. What is the overall signal attenuation through the fiber assuming there are no connectors or splices?

Accepted Answer

A)  15.23db
B)  16.98db
C)  17.12db
D)  16.62dbE) All of the above
F) B) and D) B

Question 2

Losses in photonic crystal fibers are reduced to a level of

Accepted Answer

A)  0.1db/km
B)  0.2db/km
C)  0.3db/km
D)  0.4db/kmE) A) and C)
F) A) and D)

Question 3

. A decibel may be defined as the ratio of input and output optical power for a particular optical wavelength.

Accepted Answer

A) True 
 B)False

Question 4

The optical fiber incurs a loss in signal power as light travels down the fiber which is called as

Accepted Answer

A)  scattering
B)  attenuation
C)  absorption
D)  refractionE) All of the above
F) A) and B)

Question 5

A step-index fiber has core refractive index 1.46 and radius 4.5?m. Find the cutoff wavelength to exhibit single mode operation. Use relative index difference as 0.25%.

Accepted Answer

A)  1.326?m
B)  0.124?m
C)  1.214?m
D)  0.123?mE) All of the above
F) C) and D)

Question 6

For lower bandwidth applications,

Accepted Answer

A)  single mode fiber is advantageous
B)  photonic crystal fibers are advantageous
C)  coaxial cables are advantageous
D)  multimode fiber is advantageousE) C) and D)
F) All of the above

Question 7

A graded-index fiber has a core with parabolic refractive index profile of diameter of 30?m, NA=0.2, ?=1?m. Estimate the normalised frequency.

Accepted Answer

A)  19.32
B)  18.84
C)  16.28
D)  17.12E) A) and B)
F) None of the above

Question 8

Refraction is the

Accepted Answer

A)  bending of light waves
B)  reflection of light waves
C)  diffusion of light waves
D)  refraction of light wavesE) B) and C)
F) None of the above

Question 9

A multimode step index fiber has a normalized frequency of 72. Estimate the number of guided modes.

Accepted Answer

A)  2846
B)  2592
C)  2432
D)  2136E) B) and C)
F) A) and D)

Question 10

In index-guided photonic crystal fiber structure, the dark areas are air holes. What does white areas suggests?

Accepted Answer

A)  air
B)  silica
C)  water
D)  plasmaE) None of the above
F) A) and B)

Question 11

The phenomenon which occurs when an incident wave strikes an interface at an angle greater than the critical angle with respect to the normal to the surface is called as

Accepted Answer

A)  refraction
B)  partial internal reflection
C)  total internal reflection
D)  limiting case of refractionE) B) and C)
F) All of the above

Question 12

Conventional optical fibers has more transmission losses than photonic crystal fibers. State whether the statement is true or false.

Accepted Answer

A) True 
 B)False

Question 13

A device which reduces the intensity of light in optical fiber communications is

Accepted Answer

A)  compressor
B)  optical attenuator
C)  barometer
D)  reducerE) A) and D)
F) A) and C)

Question 14

The periodic arrangement of cladding air holes in photonic band gap fibers provides for the formation of a photonic band gap in the

Accepted Answer

A)  h-plane of fiber
B)  e-plane of fiber
C)  e-h-plane of fiber
D)  transverse plane of fiberE) A) and B)
F) C) and D)

Question 15

One of the given statements is true for intermodal dispersion. Choose the right one.

Accepted Answer

A)  low in single mode and considerable in multimode fiber
B)  low in both single mode and multimode fiber
C)  high in both single mode and multimode fiber
D)  high in single mode and low in multimode fiberE) A) and C)
F) None of the above

Question 16

. When the input and output power in an optical fiber is 120?W & 3?W respectively and the length of the fiber is 8 km. What is the signal attenuation per km for the fiber?

Accepted Answer

A)  3db/km
B)  2db/km
C)  1db/km
D)  4db/kmE) A) and B)
F) B) and D)

Question 17

Most of the optical power is carried out in core region than in cladding. State true or false:

Accepted Answer

A) True 
 B)False  True

Question 18

. Skew rays follow a

Accepted Answer

A)  hyperbolic path along the axis
B)  parabolic path along the axis
C)  helical path
D)  path where rays changes angles at core-cladding interfaceE) B) and C)
F) None of the above

Question 19

Photonic crystal fibers also called as

Accepted Answer

A)  conventional fibers
B)  dotted fibers
C)  stripped fibers
D)  holey fibersE) None of the above
F) B) and C)

Question 20

What is the unit of normalized frequency?

Accepted Answer

A)  hertz
B)  meter/sec
C)  coulombs
D)  it is a dimensionless quantityE) B) and D)
F) A) and D) D

Exam 2: Optical Fibers: Refraction, Transmission Losses, and Dispersion

If the input power 100?W is launched into 6 km of fiber, the mean optical power at the fiber output is 2?W. What is the overall signal attenuation through the fiber assuming there are no connectors or splices?

Correct AnswerverifiedB

Losses in photonic crystal fibers are reduced to a level of

Correct AnswerverifiedShow Answer

. A decibel may be defined as the ratio of input and output optical power for a particular optical wavelength.

Correct AnswerverifiedShow Answer

The optical fiber incurs a loss in signal power as light travels down the fiber which is called as

Correct AnswerverifiedShow Answer

A step-index fiber has core refractive index 1.46 and radius 4.5?m. Find the cutoff wavelength to exhibit single mode operation. Use relative index difference as 0.25%.

Correct AnswerverifiedShow Answer

For lower bandwidth applications,

Correct AnswerverifiedShow Answer

A graded-index fiber has a core with parabolic refractive index profile of diameter of 30?m, NA=0.2, ?=1?m. Estimate the normalised frequency.

Correct AnswerverifiedShow Answer

Refraction is the

Correct AnswerverifiedShow Answer

A multimode step index fiber has a normalized frequency of 72. Estimate the number of guided modes.

Correct AnswerverifiedShow Answer

In index-guided photonic crystal fiber structure, the dark areas are air holes. What does white areas suggests?

Correct AnswerverifiedShow Answer

The phenomenon which occurs when an incident wave strikes an interface at an angle greater than the critical angle with respect to the normal to the surface is called as

Correct AnswerverifiedShow Answer

Conventional optical fibers has more transmission losses than photonic crystal fibers. State whether the statement is true or false.

Correct AnswerverifiedShow Answer

A device which reduces the intensity of light in optical fiber communications is

Correct AnswerverifiedShow Answer

The periodic arrangement of cladding air holes in photonic band gap fibers provides for the formation of a photonic band gap in the

Correct AnswerverifiedShow Answer

One of the given statements is true for intermodal dispersion. Choose the right one.

Correct AnswerverifiedShow Answer

. When the input and output power in an optical fiber is 120?W & 3?W respectively and the length of the fiber is 8 km. What is the signal attenuation per km for the fiber?

Correct AnswerverifiedShow Answer

Most of the optical power is carried out in core region than in cladding. State true or false:

Correct AnswerverifiedTrue

. Skew rays follow a

Correct AnswerverifiedShow Answer

Photonic crystal fibers also called as

Correct AnswerverifiedShow Answer

What is the unit of normalized frequency?

Correct AnswerverifiedD

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True

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D