Optical Fiber Communication
Note: Answer of questions are in bold options
UNIT – 4
1. The amount of radiance in planer type of LED structures is
a) Low
b) High
c) Zero
d) Negligible
2. In surface emitter LEDs, more advantage can be obtained by using
a) BH structures
b) QC structures
c) DH structures
d) Gain-guided structure
3. DH surface emitter generally give
a) More coupled optical power
b) Less coupled optical power
c) Low current densities
d) Low radiance emission into-fiber
4. In optical fiber communication, the electrical signal dropping to half its constant value due to modulated portion of optical signal corresponds to
a) 6 dB
b) 3 dB
c) 4 dB
d) 5 db
5. The depletion region must be to allow a large fraction of the incident light to be absorbed in the device (photodiode).
a) Thick
b) Thin
c) Long
d) Inactive
6. The process of excitation of an electron from valence band to conduction band leaves an empty hole in the valence band and is called as
a) Detection
b) Absorption
c) Degeneration of an electron-hole pair
d) Regeneration of an electron-hole pair
7. The electron hole pairs generated in a photodiode are separated by the
a) Magnetic field
b) Electric field
c) Static field
d) Depletion region
8. The photocurrent of an optical detector should be
a) Less
b) More
c) Linear
d) Non-linear
9. How many types of optical detectors are available?
a) One
b) Four
c) Two
d) Three
10. The fraction of incident photons generated by photodiode of electrons generated collected at detector is known as
a) Quantum efficiency
b) Absorption coefficient
c) Responsivity
d) Anger recombination
11. In photo detectors, energy of incident photons must be band gap energy
a) Lesser than
b) Greater than
c) Same as
d) Negligible
12. The width of depletion region is dependent on of semiconductor.
a) Doping concentrations for applied reverse bias
b) Doping concentrations for applied forward bias
c) Properties of material
d) Amount of current provided
13. has more sophisticated structure than p-i-n photodiode.
a) Avalanche photodiode
b) p-n junction diode
c) Zener diode
d) Varactor diode
14. The phenomenon leading to avalanche breakdown in reverse-biased diodes is known as
 |
a) Auger recombination
b) Mode hopping
c) Impact ionization
d) Extract ionization
15. In the optical channel bandwidth is divided into non-overlapping frequency bands.
a) Time division multiplexing
b) Frequency division multiplexing
c) Code division multiplexing
d) De-multiplexing
No comments:
Post a Comment