the Light: Fiber Optics
engineers are always looking to increase the amount of data transmitted over
networks at higher speeds. The ability
to transmit large amounts of data quickly is, after all, the most fundamental
building block of networking technology.
Of all the inventions in recent years, perhaps fiber optic cable,
because of its speed, reliability, and low cost, is one of ITs most
interesting and important advancements.
Fiber optic technology has made the term broadband a household word,
and it will likely be the future of high-speed data transmission.
A fiber optic
system is similar in many ways to the older and less reliable copper system
that it is replacing (Fiber). Whereas
copper wiring uses a series of electronic pulses to transmit data, fiber optics
uses pulses of light, either in the form of LED (light emitting diode) or ILD
(injection-laser diode) (Introduction).
The cabling itself consists of five elements: an optic core, an optic
cladding, a buffer material, a strength material, and an outer jacket
(Introduction). The actual fiber is
usually made from either glass or plastic fibers (Network Cabling). The different materials result in an
extremely reflective surface, which allows light pulses traveling along the
fiber core to reflect off the core and cladding as they travel down the length
of the cable.
fiber-optic network consists of three components at the most basic point-point
level: the optical transmitter, the cabling itself, and the optical receiver
(Fiber). At one end is the
transmitter. The transmitter is the
place of origin for information coming on to the fiber optic lines
(Fiber). The transmitter translates
the information into coded light pulses, which are sent, either by LED or ILD,
through a lens to the cabling.
Sometimes the cable is aligned to make direct contact with the
lens. LEDs are not as good a light
source as ILDs, but their low cost makes them ideal for smaller networks
information, in the form of light pulses, travels very quickly through the
cabling. The cabling is so reflective
that it uses a phenomenon known as total internal reflection (Fiber). What this means is that light cannot escape
the glass and is simply forced down the length of the cable. Therefore, high speeds can be achieved, and
the risk of lost data or packets is very low. For systems requiring
transmission over great distances or where two or more fiber-optic cables must
be joined together, an optical splice is commonly used (Introduction). The data travels along the length of the
fiber using two different schemes: one involves modulated light which is turned
either on or off, while the other uses a linear signal which varies in
intensity between predetermined levels (Introduction).
Once the light
pulses reach their destination, they are channeled into an optical
receiver. As one can imagine, the
receiver does just the opposite of the transmitter: it receives the pulses of
light and decodes them back into recognizable data. The data is then ready for output to an electronic device, such
as a data terminal.
Advantages of Fiber
Fiber has several
distinct advantages over traditional copper-based and coaxial cable. These include:
Immunity from interference.
Immunity from atmospheric conditions. (Since the late 1980s, fiber-optics have
been used undersea to enhance bandwidth across overseas and in distant areas)
Smaller, lighter, and more flexible cabling.
More secure fiber is easy to monitor but difficult to
Fiber optics, because it is a relatively new
technology, is still suffering from some growing pains despite its rapid
deployment and the fact that IT has, for the most part, embraced the
technology. The largest disadvantage is
that it is still incompatible with much of the electronic hardware systems that
make up todays world (Fiber). Hence,
new fiber optic hardware applications must often be retrofitted to work with
older hardware. And as with any newer
technology, there are bottlenecks. Most
of these occur at the point of conversion.
When a portion of the chain encounters heavy traffic, information can
become jammed, resulting in slow performance (Fiber). However, many of these bottlenecks will
likely be alleviated as the processing power of transmitters and receivers
increases, and engineering tweaks will likely improve overall performance.
optic technology is also expensive.
Although the price of fiber has become competitive with copper due to
high demand and increased supply, transmitters, converters, repeaters, and the
necessary connecting hardware remains high, meaning that the initial outlay for
fiber can be expensive. However, as the
technology improves and demand increases, prices will drop and the price of
fiber will become a moot point.
problem that plagued fiber optics until recently was lack of a coherent
standard. However, that problem was
taken care of with the ANSI/NEIS 301 standard in November of 1999, which, among
other things, describes procedures for installing, testing, and commissioning
of systems that use fiber-optic cables and related components
(Rosenburg). The standard even denotes
the proper methods for placing and reinforcing cabling. While the lack of a standard held fiber
optics back to a certain extent, the well-defined standard will go a long way
toward making the technology more commonplace.
Fiber has many
uses. The first commercial installation
occurred in 1977, with phone companies being among the first to scrap their old
and unreliable copper lines in favor of fiber.
Many telephone companies today use fiber optics throughout their systems
and as a long distance connection between city phone systems (Fiber). Cable television companies have also begun
using fiber optics, which has allowed for the development of the cable modem, a
device allowing home users to have roughly the same bandwidth as a T1
nursery of the Internet and perennially in need of more bandwidth, have
implemented fiber optics in their LANs and overall networking structures. In 1999, Princeton Theological seminary
upgraded their network to Gigabit Ethernet speeds by implementing fiber optics
(Knisley). Power companies have used
fiber optics in their communication systems, allowing for easy monitoring of
power grids. The ability of fiber
optics to send large amounts of data quickly has also been recognized by the
data storage industry: fiber channel technology, implemented within the SCSI
(small computer system interface) architecture, allows large drives to have
has a bright future and will likely become the de facto standard for the speedy
transmission of large amounts of data.
Prices will continue to fall, and new applications will be invented as
engineers find new ways of exploiting the technology. It has been suggested that fiber technology will eventually find
its way into microprocessors, which are still copper-based. Its probably safe to say that in the
future, many of the electronic devices we use on a daily basis will be riding
Bandwidth 20,000 Cables Under the Sea. Telephony. 21
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Introduction to Fiber Optics. Copyright 2001 Communications Specialties, Inc.
Princeton Graduates into Fiber-Optic Cabling. CEE
Rosenburg, Paul. The
New Fiber Optic Installation Standard.