Deck 4: Optical Fiber Communication: Scattering, Polarization, and Dispersion

Question 1

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

Answer 1

negative-dispersion fiber

Question 2

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

Answer 2

linear scattering losses

Question 3

Dominant intrinsic loss mechanism in low absorption window between ultraviolet and infrared absorption tails is

A)mie scattering
B)rayleigh scattering
C)stimulated raman scattering
D)stimulated brillouin scattering

Answer 3

rayleigh scattering

Question 4

Rayleigh scattering can be reduced by operating at smallest possible wavelengths.

Question 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

Question 6

Mie scattering has in-homogeneities mainly in

A)forward direction
B)backward direction
C)all direction
D)core-cladding interface

Question 7

The in-homogeneities in Mie scattering can be reduced by coating of a fiber.

Question 8

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

Question 9

The phonon is a quantum of an elastic wave in a crystal lattice.

Question 10

A single-mode optical fiber has an attenuation of 0.3dB/km when operating at wavelength of 1.1?m. The fiber core diameter is 4?mand bandwidth is 500 MHz. Find threshold optical power for stimulated Brillouin scattering.

A)11.20 mw
B)12.77 mw
C)13.08 mw
D)12.12 mw

Question 11

0.4 dB/km, 1.4?m, 6?m, 550MHz. Find threshold optical power for stimulated Raman scattering.

A)1.98 w
B)1.20 w
C)1.18 w
D)0.96 w

Question 12

Stimulated Brillouin scattering is mainly a

A)forward process
B)backward process
C)upward process
D)downward process

Question 13

High frequency optical phonon is generated in stimulated Raman scattering. State true or false

Question 14

 For many applications which involve optical fiber transmission, an intensity modulation optical source is not required.

Question 15

The optical source used for detection of optical signal is

A)ir sensors
B)photodiodes
C)zener diodes
D)transistors

Question 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

Question 17

The beat length in a single mode optical fiber is 8 cm, when light from a laser with a peak wavelength 0.6?m is launched into it. Estimate the modal birefringence.

A)1×10^?5
B)3.5×10^?5
C)2×10^?5
D)4×10^?5

Question 18

Beat length of a single mode optical fiber is 0.6cm. Calculate the difference between propagation constants for the orthogonal modes

A)69.8
B)99.86
C)73.2
D)104.66

Question 19

A polarization maintaining fiber operates at a wavelength 1.2?m and have a modal birefringence of 1.8*10^-3. Calculate the period of perturbation.

A)0.7 seconds
B)0.6 seconds
C)0.23 seconds
D)0.5 seconds

Question 20

When two components are equally excited at the fiber input, then for polarization maintaining fibers ??gshould be around

A)1.5ns/km
B)1 ns/km
C)1.2ns/km
D)2ns/km

Question 21

Polarization modal noise can _________ the performance of communication system.

A)degrade
B)improve
C)reduce
D)attenuate

Question 22

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

Question 23

What does ISI stands for in optical fiber communication?

A)invisible size interference
B)infrared size interference
C)inter-symbol interference
D)inter-shape interference

Question 24

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

Question 25

The maximum bit rate that may be obtained on an optical fiber link is 1/3?.