1. 3dB optical bandwidth is always ___________ the 3dB electrical bandwidth.
Correct : B. larger than
2. A multimode graded index fiber exhibits a total pulse broadening of 0.15μsover a distance of 16 km. Estimate the maximum possible bandwidth, assuming no intersymbol interference.
Correct : C. 3.3 mhz
3. What is pulse dispersion per unit length if for a graded index fiber, 0.1μs pulse broadening is seen over a distance of 13 km?
Correct : B. 7.69ns/km
4. Chromatic dispersion is also called as intermodal dispersion. State whether the given statement true or false.
Correct : B. false
5. Chromatic dispersion is also called as intermodal dispersion. State true or false
Correct : B. false
6. The optical source used in a fiber is an injection laser with a relative spectral width σλ/λ of 0.0011 at a wavelength of 0.70μm. Estimate the RMS spectral width.
Correct : C. 0.77 nm
7. In waveguide dispersion, refractive index is independent of
Correct : D. wavelength
8. Intermodal dispersion occurring in a large amount in multimode step index fiber results in
Correct : C. pulse broadening at output
9. After Total Internal Reflection the Meridional ray
Correct : D. makes an angle equal to critical angle with the axial ray
10. Consider a single mode fiber having core refractive index n1= 1.5.
Correct : B. 0.06μsec
11. A 4 km optical link consists of multimode step index fiber with core refractive index of 1.3 and a relative refractive index difference of 1%. Find the delay difference between the slowest and fastest modes at the fiber output.
Correct : A. 0.173 μsec
12. A multimode step-index fiber has a core refractive index of 1.5 and relative refractive index difference of 1%. The length of the optical link is 6 km. Estimate the RMS pulse broadening due to intermodal dispersion on the link.
Correct : B. 86.7 ns
13. The differential attenuation of modes reduces intermodal pulse broadening on a multimode optical link. State whether the given statement is true or false.
Correct : A. true
14. The index profile of a core of multimode graded index fiber is given by-
Correct : D. n (r) = n1 [1 – 2Δ(r2/a)2]1/2; r<a
15. Intermodal dispersion in multimode fibers is minimized with the use of step-index fibers. State whether the given statement is true or false.
Correct : B. false
16. Estimate RMS pulse broadening per km due to intermodal dispersion for multimode step index fiber where length of fiber is 4 km and pulse broadening per km is 80.6 ns.
Correct : B. 20.15ns/km
17. Practical pulse broadening value for graded index fiber lies in the range of
Correct : B. 0.2 to 1 ns/km
18. The nonlinear effects in optical fibers are large. State whether the given statement is true or false.
Correct : B. false
19. How many categories of nonlinear effects are seen in optical fibers?
Correct : B. two
20. Which of the following is not related to Kerr effects?
Correct : D. stimulated raman scattering
21. Linear scattering effects are _______ in nature.
Correct : A. elastic
22. Which thing is more dominant in making a fiber function as bidirectional optical amplifier?
Correct : B. pump source
23. _________ semiconductor laser sources generally have broader bandwidths.
Correct : B. pulsed
24. Nonlinear effects which are defined by the intensity – dependent refractive index of the fiber are called as
Correct : B. kerr effects
25. Self-phase modulation causes modifications to the pulse spectrum. State whether the given statement is true or false.
Correct : A. true
26. Self-phase modulation can be used for
Correct : B. wavelength shifting
27. The beating between light at different frequencies or wavelengths in multichannel fiber transmission causes
Correct : C. phase modulation of channels
28. What is different in case of cross-phase modulation from self-phase modulation?
Correct : B. overlapping but distinguishable pulses
29. When three wave components co-propagate at angular frequency w1, w2, w3, then a new wave is generated at frequency w4, which is given by
Correct : C. w4 =w1+w2-w3
30. _____________ results from case of nonlinear dispersion compensation in which the nonlinear dispersion compensation in which the nonlinear dispersion compensation in which the nonlinear chirp caused by self-phase modulation balances, postpones, the temporal broadening induced by group velocity delay.
Correct : C. soliton propagation
31. What is a fundamental necessity in the fabrication of fibers for light transmission?
Correct : D. variation of refractive index inside the optical fiber
32. Which materials are unsuitable for the fabrication of graded index fiber?
Correct : B. mono-crystalline structures
33. How many different categories are available for the methods of preparing optical glasses?
Correct : B. 2
34. What is the first stage in liquid-phase-technique?
Correct : A. preparation of ultra-pure material powders
35. Which processes are involved in the purification stage in liquid-phase-technique?
Correct : A. filtration, co-precipitation, re-crystallization
36. At what temperature range, does the melting of multi components glass systems takes place?
Correct : C. 900-1300 degree celsius
37. Fiber drawing using preform was useful for the production of graded index fibers. State whether the given statement is true or false.
Correct : B. false
38. The minute perturbations and impurities in the fiber drawing process using preform technique can result in very high losses of
Correct : A. between 500 and 1000 db/km
39. The liquid-phase melting technique is used for the production of fibers
Correct : C. with a core diameter more than 200μm.
40. Graded index fibers produced by liquid-phase melting technique are less dispersive than step-index fibers. State whether the given statement is true or false.
Correct : A. true
41. Which of the following is not a technique for fabrication of glass fibers?
Correct : C. lave ring method
42. _____________ technique is method of preparing extremely pure optical glasses.
Correct : D. vapor phase deposition (vpd)
43. Which of the following materials is not used as a starting material in vapor-phase deposition technique?
Correct : D. b2o3
44. P2O5 is used as a _____________
Correct : A. dopant
45. How many types of vapor-phase deposition techniques are present?
Correct : B. two
46. ___________ uses flame hydrolysis stems from work on soot processes which were used to prepare the fiber with losses below 20 dB/km.
Correct : A. outside vapor phase oxidation
47. Complete the given reaction
Correct : B. 4hcl
48. In modified chemical vapor deposition, vapor phase reactant such as _________ pass through a hot zone.
Correct : A. halide and oxygen
49. _________ is the stimulation of oxide formation by means of non-isothermal plasma maintained at low pressure in a microwave cavity surrounding the tube.
Correct : D. plasma-activated chemical vapor deposition (pcvd)
50. Only graded index fibers are made with the help of vapor-phase deposition techniques. State whether true or false.
Correct : B. false
51. Modified Chemical Vapor Deposition (MCVD) process is also called as an inside vapor phase oxidation (IVPD) technique. State whether the given statement is true or false.
Correct : A. true
52. Multimode step index fiber has
Correct : A. large core diameter & large numerical aperture
53. . A typically structured glass multimode step index fiber shows as variation of attenuation in range of
Correct : C. 2.6 to 50 db km-1at wavelength 0.85μm
54. A multimode step index fiber has a large core diameter of range
Correct : A. 100 to 300 μm
55. Multimode step index fibers have a bandwidth of
Correct : B. 6 to 50 mhz km
56. Multimode graded index fibers are manufactured from materials with
Correct : B. higher purity than multimode step index fibers.
57. The performance characteristics of multimode graded index fibers are
Correct : A. better than multimode step index fibers.
58. Multimode graded index fibers have overall buffer jackets same as multimode step index fibers but have core diameters
Correct : B. smaller than multimode step index fibers.
59. Multimode graded index fibers with wavelength of 0.85μm have numerical aperture of 0.29 have core/cladding diameter of
Correct : B. 100μm/140 μm
60. Multimode graded index fibers use incoherent source only. State whether the following statement is true or false.
Correct : B. false
61. In single mode fibers, the most beneficial index profile is
Correct : B. graded index
62. The fibers mostly not used nowadays for optical fiber communication system are
Correct : A. single mode fibers
63. Single mode fibers allow single mode propagation; the cladding diameter must be at least
Correct : D. ten times the core diameter
64. A fiber which is referred as non-dispersive shifted fiber is
Correct : B. standard single mode fibers
65. Standard single mode fibers (SSMF) are utilized mainly for operation in
Correct : C. o-band
66. Fiber mostly suited in single-wavelength transmission in O-band is
Correct : B. standard single mode fibers
67. When optical fibers are to be installed in a working environment, the most important parameter to be considered is
Correct : B. mechanical property of the fiber
68. It is not important to cover these optical fibers required for transmission. State whether the given statement is true or false.
Correct : B. false
69. Optical fibers for communication use are mostly fabricated from
Correct : B. silica or multicomponent glass
70. An Si-O bond with a Young’s modulus of 9*1010Nm-1 have an elliptical crack of depth 7nm. The surface energy is 2.29 J. Estimate fracture stress for silica fiber.
Correct : A. 4.32*109nm-1
71. Calculate percentage strain at break for a Si-O bond with a fracture strength of 3.52*1010Nm-1 and Young’s modulus of 9 *109Nm-1.
Correct : D. 3.9 %
72. Stress corrosion must be considered while designing and testing optical fiber cables. State whether the given statement is true or false.
Correct : A. true
73. Which statistics are used for calculations of strengths of optical fibers?
Correct : C. wei-bull statistics
74. What does n denotes in the equation given below, if vc is the crack velocity; A is the constant for the fiber material and KI is the strength intensity factor?
Correct : B. stress corrosion susceptibility
75. Optical fibers for communication use are mostly fabricated from
Correct : B. silica or multicomponent glass
76. An Si-O bond with a Young’s modulus of 9*1010Nm-1 have an elliptical crack of depth 7nm. The surface energy is 2.29 J. Estimate fracture stress for silica fiber.
Correct : A. 4.32*109nm-1
77. Calculate percentage strain at break for a Si-O bond with a fracture strength of 3.52*1010Nm-1 and Young’s modulus of 9 *109Nm-1.
Correct : D. 3.9 %
78. Stress corrosion must be considered while designing and testing optical fiber cables. State whether the given statement is true or false.
Correct : A. true
79. Which statistics are used for calculations of strengths of optical fibers?
Correct : C. wei-bull statistics
80. . ____________ results from small lateral forces exerted on the fiber during the cabling process.
Correct : B. micro-bending
81. Microscopic meandering of the fiber core axis that is micro-bending is caused due to
Correct : A. environmental effects
82. How many forms of modal power distribution are considered?
Correct : B. two
83. What does micro-bending losses depend on?
Correct : D. mode and wavelength
84. The fiber should be________________ to avoid deterioration of the optical transmission characteristics resulting from mode-coupling-induced micro-bending.
Correct : A. free from irregular external pressure
85. The diffusion of hydrogen into optical fiber affects the ______________
Correct : B. spectral attenuation characteristics of the fiber
86. __________ can induce a considerable amount of attenuation in optical fibers.
Correct : D. radiation exposure
87. The radiation-induced attenuation can be reduced through photo-bleaching. State whether the given statement is true or false.
Correct : A. true
88. The losses due to hydrogen absorption and reaction with fiber deposits can be temporary. State whether the given statement is true or false.
Correct : B. false
89. The losses caused due to hydrogen absorption mechanisms are in the range of
Correct : C. 25 db/km to50 db/km
90. The cable must be designed such that the strain on the fiber in the cable does not exceed__________
Correct : C. 0.2%
91. How many categories exists in case of cable design?
Correct : B. three
92. How many types of buffer jackets are used in fiber buffering?
Correct : A. three
93. Loose tube buffer jackets exhibits a low resistance to movement of the fiber. State whether the given statement is true or false.
Correct : A. true
94. An inclusion of one or more structural members in an optical fiber so as to serve as a cable core foundation around which the buffer fibers may be wrapped is called _____________
Correct : D. stranding
95. Which of the following is not a strength member used in optical cable?
Correct : B. germanium
96. When the stranding approach consists of individual elements (e.g. single-fiber or multi fiber loose tube buffer) than the cable is termed as
Correct : C. layer cable
97. The primary function of the structural member is load bearing. State whether the given statement is true or false.
Correct : B. false
98. What is the Young’s modulus of Kevlar, an aromatic polyester?
Correct : D. 13 ×1010nm-2
99. The cable is normally covered with an outer plastic sheath to reduce _______________
Correct : A. abrasion
100. A measure of amount of optical fiber emitted from source that can be coupled into a fiber is termed as