Chapter 9: Introduction to Fiber Optics Key
1. Fiber optics is the transmission of information via light over a glass or specialized plastic medium.
2. Fiber optic cable carries electricity.
3. A cylindrical material called the cladding, usually made of glass or specialized plastic, constitutes the central
portion of the cable.
4. The coating or jacket of a fiber optic cable is usually made of glass.
5. Silica is a type of metal.
6. The refractive index of an optical medium such as glass or water is typically indicated by a number greater
7. Refractive index of an optical medium = speed of light in a vacuum/speed of light in the optical medium.
8. The refractive index of light through a vacuum is conventionally defined as 0.
9. Cladding is the material that surrounds the core in a fiber optic cable.
10. The cladding is made of glass or plastic in a fiber optic cable.
11. The cladding always has a higher RI than the core within a fiber optic cable.
12. In a fiber, the core and cladding are made of materials with different RIs.
13. The diameter of single-mode fiber is less than that of a typical human hair.
14. In single-mode fiber, the cladding diameter is much smaller than the core diameter.
15. Compared with single-mode fibers, multi-mode fibers have a much larger core diameter.
16. Multi-mode fibers have greater information-carrying capacity than single-mode fibers.
17. Multi-mode fiber is usually used for lower-bandwidth, shorter-distance applications than single-mode
fibers.
18. The value of the refractive index of a graded index fiber is highest in the center of the core and gradually
diminishes towards the cladding.
19. Step index fiber is only available as single-mode fiber.
20. Light waves emitted from sources such as lasers cannot be modulated by altering various properties of the
light.
21. Fiber-optic communication systems commonly operate in the infrared portion of the light spectrum.
22. Fiber-optic cables can carry multiple optical signals within the same fiber.
23. The variable c denotes the speed of light in water within the following formula: c=fë.
24. WDM can be considered the optical equivalent of FDM.
25. Fiber optic cable is immune to electromagnetic interference (EMI).
26. One of the disadvantages of optical fiber for communication is its low transmission rates.
27. A channel with a large amount of interference has a small signal to noise ratio, which in turn affects the
maximum data rate that can be transmitted, according to the Shannon-Hartley capacity theorem.
28. Copper is a safer option than fiber-optic cable in an industrial environment, where the presence of an
electrical signal could present a fire hazard.
29. Because fibers are made of either plastic or glass, they are more difficult to splice (i.e., bring together) than
copper cables.
30. Fiber-optic cable has a high attenuation.
32. The core and the cladding have the same refractive indices within a fiber optic cable.
33. When a ray of light traveling through one medium with a higher refractive index hits another medium with a
lower refractive index at an angle of incidence greater than the critical angle, a phenomenon called total
____________________ occurs.
34. The coating or jacket of fiber optic cable protects fiber from its surrounding environment and provides
____________________.
35. A fiber optic cable has two main components that have different refractive indices: they are the
____________________ and the ____________________.
36. Unlike coax cables, which transport electricity over copper wires, fiber-optic cables carry
____________________ through glass or plastic to convey information.
37. µm is an abbreviation for ____________________.
38. mm is an abbreviation for ____________________.
39. The core and cladding materials have an important property called the RI, or ____________________.
40. The refractive index is a measure of the speed of ____________________ through a material.
41. ____________________ is defined as the bending of light when a light ray crosses the boundary from one
optical medium to another with different refractive indices.
42. The coating (or jacket) of fiber optic cable surrounds the ____________________.
43. If a light ray strikes a boundary with different refractive indices at an angle of incidence that is less than the
critical angle, it undergoes ____________________.
44. ____________________ is a term used to refer to the bending of light as it travels from one medium to
another where the two media have different refractive indices.
45. Fiber-optic cables may be classified as either single-mode fiber or ____________________.
46. Which is cheaper to use, single-mode or multi-mode fiber optic cable? ____________________.
47. In fiber optics, devices similar to light bulbs are used as optical transducers at the input of fiber-optic cables
to convert electricity into light. The most commonly used devices are light emitting diodes (LED) and
48. After traveling through a fiber optic cable, an output transducer such as a photodiode (PD) or
____________________ converts light back into electrical pulses.
49. Fiber connectors serve the purpose of ____________________ one fiber segment to another with minimal
loss of light.
50. WDM stands for ___________________________________.
51. Frequency (f), speed (c) and wavelength (ë) of an EM wave are related to each other by the following
equation ____________________.
52. Bringing together or fusing two pieces of fiber is called ____________________.
53. A common term in the telecommunications and IT industry to describe a fiber-optic infrastructure that has
been established but is not yet being used is ____________________.
54. Advantages of fiber-optic cable include high transmission rates, immunity to EMI, low attenuation, high
security, small weight and size, and ____________________ power consumption.
55. Disadvantages of ____________________ cable include higher installation and maintenance costs and
difficulty in splicing.
56. A physical medium that is capable of transmitting light is called a(n) ____________________ medium.
57. An arrangement frequently used by cable service providers to convert signals from coaxial cable into optical
signals at the curb to be carried across fiber-optic cable to the service provider’s facilities is called HFC, short
for ____________________.
58. ____________________ are made up of a few basic components, including the core, cladding, and coating
or jacket.
59. Fiber optic cables are used for which of the following?
60. A nineteenth-century device constructed by Alexander Graham Bell that demonstrated how sound could be
transmitted via an optical beam traveling through free space was called:
A. The phonograph
61. The concentric configuration of fiber optic cable is called what kind of arrangement?
62. The light signal carrying information through fiber optic cable essentially travels through which of the
following?
63. The diameter of the core of a fiber optic cable can range from:
64. Which of the following is a measure of the speed of light through a material?
65. Light travels fastest in:
66. Which of the following is the speed of light in a vacuum?
67. TIR may be considered to be an extreme case of:
68. A ray of light striking the core/cladding boundary is totally reflected from the boundary back into the core if
the ray strikes the boundary at an angle that is greater than:
A. 1 degree
69. A fiber-optic cable with a uniform refractive index throughout its core is classified as:
70. A fiber optic cable whose core refractive index is nonuniform and varies gradually is classified as:
71. A device that converts one form of energy to another, such as light into electricity, electricity into sound,
and so on, is called:
72. Multi-mode fiber-optic cable whose core refractive index is nonuniform and varies gradually is called:
73. Multi-mode fiber-optic cable with a uniform refractive index throughout its core is called:
74. Single-mode fiber-optic cable whose core refractive index is nonuniform and varies gradually is called:
75. Single-mode fiber-optic cable with a uniform refractive index throughout its core is called:
76. A device that efficiently inserts light into and out of a fiber optic cable at appropriate angles (greater than
the critical angle) and to minimize insertion loss is called:
A. An inducer
77. When a large number of channels are multiplexed onto a single fiber-optic cable, the approach is called:
78. When a small number of channels are multiplexed onto a single fiber-optic cable, the approach is called:
79. A typical DWDM system might have how many channels?
80. A typical CWDM system might have how many channels?
81. Which of the following is an advantage of fiber optic cable?
82. Which of the following is a disadvantage of fiber optic cable?
83. A device that can be adjusted to emit light at a variety of wavelengths is called a:
84. Aside from fiber optics, provide some examples of people using light to convey information.
85. Explain total internal reflection.
86. Describe the difference between single-mode and multi-mode fiber.
87. Why are systems that use single-mode fiber more costly to set up than multi-mode fiber?
88. How is light guided within a graded index fiber different from how light is guided through step index fiber?
89. What is a photodiode?
90. Why does fiber optic cable provide greater security than copper?
91. What does the term “dark fiber” mean?
92. Describe why the medical field has benefited from fiber optics technology.
93. Besides computer networking, describe how the computing field benefits from fiber optics.
94. What is “hybrid fiber coaxial”?