10 Question-Answer on optical fibers
1. The main objective of an optical source is:
(a) To demodulate the electrical signal
(b) To detect the signal
(c) To convert the electrical energy into an optical energy
(d) All of these
Ans: ( c)
2. The number of telephonic messages which are carried by a fiber at an instant with much less intensity loss are
(a) 2400
(b) 2200
(c) 2000
(d) 1800
Ans: ( c)
3. Lasers are used in alignment because
(a) They are coherent
(b) They are highly directional
(c) Both (a) and (b)
(d) None of these
Ans: ( c)
4. Which fibers are less expensive and simple to construct?
(a) Single-mode step index fiber
(b) Multi-mode step index fiber
(c) Multi graded-index fiber
(d) All are equally expensive.
Ans: (b)
5. A laser is a coherent source because it contains
(a) Many wavelength
(b) Uncoordinated wave of particular wave length
(c) Coordinated waves of many wavelength
(d) Coordinated waves of particular wave length
Ans: ( d)
6. The population inversion in helium-neon laser is produced by
(a) Photon excitation
(b) Electron excitation
(c) Inelastic atomic collisions
(d) Chemical reaction
Ans:( b)
7. In He-Ne laser the most favorable ratio of helium to neon for satisfactory laser action is:
(a) 1:4
(b) 4:1
(c) 1:7
(d) 7:1
Ans: (d)
8. The population inversion necessary for laser action used in solid state laser is:
(a) Electrical discharge
(b) Inelastic atom-atom collisions
(c) Direct conversion
(d) Optical pumping
Ans: (d)
9. Small values of numerical aperture(NA) decrease the pulse dispersion but increase losses due to
(a) Scattering
(b) Absorption
(c) Bending
(d) Micro bending
Ans: ( d)
10. The difference in the refractive index of the fiber core and fiber cladding in step-index fiber is typically
(a) 0.01%
(b) 1%
(c) 10%
(d) 25%
Ans: (b)