Fiber Optics
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1. Mode Field Diameter The diameter of the light emerging from the end of the
fiber is also termed...
2. core, cladding, and The basic construction of fiber is:
prime coating
3. zig-zag A multimode step-index fiber transmits light down the
fiber in what pattern?
4. Single-Mode This type of fiber has only one mode for the light to
travel down.
5. glass core and plastic Plastic-clad silica cables have what kind of construc-
cladding tion?
6. material dispersion different wavelengths travel at different speeds along
the same path
7. 5-10 micrometers the typical core diameter range for single-mode fiber
optic cables
8. 125 micrometers typically the cladding of a fiber, regardless of its core
size is what diameter?
9. waveguide disper- a singe wavelength travels at different speeds in dif-
sion ferent materials
10. .50 km if you are using a fiber optic cable that is designed to
transmit 600 MHz for a distance of .75 km, how far
could an 800 MHz signal travel on the same cable
11. microbend loss little bumps in the core at the junction of the core and
cladding are called?
12. frequency goes up distance goes down
13. attenuation dB/Km is how ________ of optical power is measured
14. numerical aperature The _______ ________ of the optical source, fiber,
and optical receiver must match for best transmission
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15. tight buffer allows a lower tensile strength but a higher impact
and crush resistance
16. plenum-duty fiber type fiber used if you are installing it in a return air
vent / space in a building
17. strength members the part of the fiber optic cable that allows you to pull
it when you are installing it
18. MHz per Km many manufacturers specify bandwidth-length in
______ instead of specifying dispersion in the modal
offerings
19. 300 dB/Km plastic fiber would have an attenuation in the range of
20. shorter wavelength rayleigh scattering decreases with ________ light
waves
21. Graded Index Fiber fiber optic cable constructed by layers of increasing
index of refraction core material
22. single mode fiber when using ________ fiber optic cable you must wor-
ry about matching the cable to the frequency of the
light you are transmitting more than other types of
cable
23. single mode fiber has smaller core so it is particular about light frequen-
cy
24. modal dispersion doesn't exist in single mode fiber (zig-zag flatlines
out)
25. must go slower but in a single mode fiber optic cable, you can send a
greater distance 1300nm wavelength faster but for a shorter distance,
what would be the effect if you would send a 1500nm
wavelength down this same cable?
26. blue fiber number 1
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27. orange fiber number 2
28. green fiber number 3
29. brown fiber number 4
30. slate fiber numer 5
31. white fiber number 6
32. red fiber number 7
33. black fiber number 8
34. yellow fiber number 9
35. violet fiber number 10
36. rose fiber number 11
37. aqua fiber number 12
38. characteristics that size of the fiber, composition of the fiber, light injected
affect light propaga- into the fiber
tion down fibers
39. swept cable tells exactly what loss will be down it
40. glass fiber glass core & glass cladding
41. PCS (plastic clad sili- glass core and plastic cladding
ca)
42. plastic fiber plastic core and plastic cladding (cheaper, more flex-
ible, more durable, but more loss)
43. modes can be simplified to mean the number of potential
paths for a light ray to travel down a fiber
44. multimode step index simplest type of fiber; core diameter from 100-970
um and includes glass, PCS, & plastic; light zig-zags
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down the fiber with many possible paths; pulse
spreading results because of so many different pos-
sible paths
45. modal dispersion spreading of signal, "zig-zagging" of the wave
46. graded-index fiber fiber made up of many concentric layers of glass
designed to bend the light towards the center core;
reduces modal dispersion to 1 ns/km; core diameter
50, 62.5, or 85 um; cladding of 125 um
47. graded-index fiber highest quality, expense in installation, different light
lengths allow it to arrive faster
48. single mode fiber cladding must be 10x as thick as core; one path only
so no modal dispersion; 417-1700 Mbps & still cost
effective; different fibers designed for different light
wavelenths
49. higher frequency more attenuation
50. fiber performance plastic - plastic coated silica (PCS) - step index glass
from lowest to high- - graded index - single mode
est
51. smaller core usually means better performance
52. glass fibers perform better than plastic fibers
53. modal dispersion occurs only in multimode fibers
54. higher frequencies can be sent for shorter distances; single mode fibers
are specified by dispersion
55. attenuation loss of optical power as light travels through the
fiber; measured in dB/Km; 300 dB/Km for plastic, .21
dB/Km for single mode
56. scattering the loss of optical power due to imperfections in the
fiber and from the basic structure of the fiber
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57. rayleigh scattering caused by density and compositional variations in the
fiber that are natural by-products of manufacturing
58. absorption loss of optical energy because impurities in the fiber
absorb it and dissipate it as a small amount of heat
59. microbend loss bumps misguide the light and make it bounce out of
the core and into the jacket
60. macrobend loss caused by bending the entire fiber in too tight a circle
therefore not allowing the light to continue down the
fiber
61. numerical aperature the light gathering ability of the fiber; a cone shaped
area of angles that the light will properly enter the fiber
so that the resulting angles keep the light in the fiber
62. fibers with high band- fibers that have a lower numerical aperature; they
width allow fewer modes
63. large numerical aper- promotes more modal dispersion
ature
64. tensile strength ability of a fiber to be stretched or pulled without
breaking; fiber _______ _______ exceeds a steel
filament of the same size
65. cause of weakness in microscopic cracks on the surface, flaws within the
a fiber fiber
66. important fiber optic tensile strength, ruggedness, durability, flexibility, en-
cable considerations vironment, temperature, and appearance
67. cabling outer protective structure surrounding one or more
fibers
68. loose buffer there is air space between the fiber and the cable;
larger bend radius; higher tensile strength; lower im-
pact and crush resistance; gell filler
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69. tight buffer no air space; smaller bend radius; lower tensile
strength; higher impact & crush resistance; higher
impact of temperature
70. strength members add mechanical strength to the fiber; important during
installation for pulling; made of kevlar aramid yarn,
steel, or fiberglass epoxy rods
71. jacket provides protection from the effects of abrasion, oil,
ozone, alkali, solvents, etc.; cables can contain sev-
eral layers; outer layer is called sheath
72. indoor cables applications include: simplex cables, duplex cables,
multifiber cables, heavy/light/plenum-duty cables, un-
dercarpet cables
73. outdoor cables used outside of a building; must withstand harsher
environment conditions
74. overhead outdoor ca- strung from telephone poles
bles
75. direct burial outdoor in a trench and covered
cables
76. indirect burial out- inside a duct or conduit
door cables
77. submarine outdoor cable is underwater
cables
78. advantages of fiber wide bandwidth (1 THz), low loss, electromagnet-
optics ic immunity, security, light weight (9lbs/100ft vs
80lbs/1000ft for copper), small size, safety
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