ch.three
fiber-optic cable
Summary
■ Fiber-optic cable has the following advantages: provides for data security,
immune to electromagnetic interference, lightweight and small in diameter,
safe from fire and explosion, wide bandwidth, corrosion- and water-resistant,
supports data transmission over longer distances than copper core cable.
■ Light is described in wavelengths.
■ A wavelength is the total distance the electromagnetic wave or light wave
travels during one full cycle.
■ Wavelengths are measured in nanometers (nanometer), or one billionth of a
meter.
■ Fiber-optic cable cores are composed of either glass or plastic.
■ The glass or plastic core is surrounded by cladding, which restricts the light
to the core area.
■ Scattering is the loss of light due to impurities in the core material.
■ Dispersion is the distortion of light waves caused by the light reflecting from
the cladding material and arriving at different times at the far end of the cable.
■ Extrinsic losses are caused by physical factors not normally found in the core
material, such as at splices and connector locations.
■ Two broad classifications of fiber-optic cable based on its ability to carry light
are multimode and single-mode.
■ Single-mode fiber-optic cable has a smaller core diameter than multimode
fiber-optic cable and carries light farther and with less attenuation.
■ Two classifications of multimode fiber-optic cable are graded-index and
step-index.
■ Graded-index multimode fiber-optic cable is designed with a varying grade
of core material that allows for maximum light conduction at the center of
the core. Step-index multimode fiber-optic cable does not have a special core
design and is therefore greatly affected by dispersion.
■ The 802.3z standard describes the 1000BaseSX, 1000BaseLX, and 1000BaseCX
Gigabit Ethernet classifications.
■ The 802.3ae 10 Gigabit Ethernet standard describes the 10GBaseSR,
10GBaseLR, 10GBaseEW, and 10GBaseER classifications.
■ 10GBaseW is a collection of cable standards such as 10GBaseSW, 10GBaseLW,
and 10GBaseEW.
■ FDDI is used mainly as a backbone for large network systems such as a
MAN or a WAN.
■ FDDI is structured as a pair of rings.
■ A splice that is joined by heat is called a fusion splice.
■ A light source and fiber-optic light meter is used to test short runs of fiber-
optic cable by comparing the amount of light injected in one end of the cable
to the light power at the other end of the cable.
■ The OTDR is used to measure the effects of scattering and cabling faults in
long fiber-optic cable runs. It can also measure the distance to a cable fault
or break.
■ Fiber-optic cable has the following advantages: provides for data security,
immune to electromagnetic interference, lightweight and small in diameter,
safe from fire and explosion, wide bandwidth, corrosion- and water-resistant,
supports data transmission over longer distances than copper core cable.
■ Light is described in wavelengths.
■ A wavelength is the total distance the electromagnetic wave or light wave
travels during one full cycle.
■ Wavelengths are measured in nanometers (nanometer), or one billionth of a
meter.
■ Fiber-optic cable cores are composed of either glass or plastic.
■ The glass or plastic core is surrounded by cladding, which restricts the light
to the core area.
■ Scattering is the loss of light due to impurities in the core material.
■ Dispersion is the distortion of light waves caused by the light reflecting from
the cladding material and arriving at different times at the far end of the cable.
■ Extrinsic losses are caused by physical factors not normally found in the core
material, such as at splices and connector locations.
■ Two broad classifications of fiber-optic cable based on its ability to carry light
are multimode and single-mode.
■ Single-mode fiber-optic cable has a smaller core diameter than multimode
fiber-optic cable and carries light farther and with less attenuation.
■ Two classifications of multimode fiber-optic cable are graded-index and
step-index.
■ Graded-index multimode fiber-optic cable is designed with a varying grade
of core material that allows for maximum light conduction at the center of
the core. Step-index multimode fiber-optic cable does not have a special core
design and is therefore greatly affected by dispersion.
■ The 802.3z standard describes the 1000BaseSX, 1000BaseLX, and 1000BaseCX
Gigabit Ethernet classifications.
■ The 802.3ae 10 Gigabit Ethernet standard describes the 10GBaseSR,
10GBaseLR, 10GBaseEW, and 10GBaseER classifications.
■ 10GBaseW is a collection of cable standards such as 10GBaseSW, 10GBaseLW,
and 10GBaseEW.
■ FDDI is used mainly as a backbone for large network systems such as a
MAN or a WAN.
■ FDDI is structured as a pair of rings.
■ A splice that is joined by heat is called a fusion splice.
■ A light source and fiber-optic light meter is used to test short runs of fiber-
optic cable by comparing the amount of light injected in one end of the cable
to the light power at the other end of the cable.
■ The OTDR is used to measure the effects of scattering and cabling faults in
long fiber-optic cable runs. It can also measure the distance to a cable fault
or break.
Review Questions
Answer the following questions on a separate sheet of paper. Please do not write in this book.
1. What are seven advantages of fiber-optic cable?
2. Light is measured in _____.
3. What does the abbreviation nm represent?
4. What is the wavelength range of visible light?
5. What are the three common wavelengths associated with fiber-optic cable?
6. What is dispersion?
7. Name three physical factors that contribute to extrinsic losses.
8. What are the two classifications of fiber-optic cable based on the diameter of
the core?
9. How does the diameter of the fiber-optic cable core affect the distance light
can travel?
10. Fiber-optic cable core diameter is expressed in _____.
11. What are the two most common sizes of multimode fiber-optic cable?
12. How can the light distance-carrying capacity of a multimode cable be
improved?
13. What do the following 10 Gigabit Ethernet acronyms represent: SW, LW,
and EW?
14. How is FDDI structured?
15. Why does FDDI use two rings of cable?
16. What are the five most common types of fiber-optic cable connector?
17. What are some common causes of attenuation associated with fiber-optic
cable splices?
18. Using heat to join two fiber-optic cores is called a(n) _____ splice.
19. What is required to test a short run of fiber-optic cable?
20. What device is commonly used to test long runs of fiber-optic cable?
21. What principle of fiber-optic cable loss does the OTDR use for measurements?
Answer the following questions on a separate sheet of paper. Please do not write in this book.
1. What are seven advantages of fiber-optic cable?
2. Light is measured in _____.
3. What does the abbreviation nm represent?
4. What is the wavelength range of visible light?
5. What are the three common wavelengths associated with fiber-optic cable?
6. What is dispersion?
7. Name three physical factors that contribute to extrinsic losses.
8. What are the two classifications of fiber-optic cable based on the diameter of
the core?
9. How does the diameter of the fiber-optic cable core affect the distance light
can travel?
10. Fiber-optic cable core diameter is expressed in _____.
11. What are the two most common sizes of multimode fiber-optic cable?
12. How can the light distance-carrying capacity of a multimode cable be
improved?
13. What do the following 10 Gigabit Ethernet acronyms represent: SW, LW,
and EW?
14. How is FDDI structured?
15. Why does FDDI use two rings of cable?
16. What are the five most common types of fiber-optic cable connector?
17. What are some common causes of attenuation associated with fiber-optic
cable splices?
18. Using heat to join two fiber-optic cores is called a(n) _____ splice.
19. What is required to test a short run of fiber-optic cable?
20. What device is commonly used to test long runs of fiber-optic cable?
21. What principle of fiber-optic cable loss does the OTDR use for measurements?