Introduction
In recent years Fiber Optics has steadily replaced copper wire as the appropriate means of communication signal transmission. Fiber spans long distances between local phone systems as well as provides the backbone for many network systems. Other system users include university campuses, office buildings, industrial plants, and electric utility companies. Fiber is now making its way into residential communities also known as the "last mile". As the bandwidth requirements increase for residential users, fiber optic "last mile" networks will become more and more the norm rather than the exception. Today there are only a handful of Fiber to the Home (FTTH) networks deployed across the country, however the number is beginning to rapidly increase. Homeowners that are connected to these networks will share the distinction and advantage in their ability to obtain the latest and best broadband services.
Fiber-Optic Technology

A Fiber Optic system is similar to the copper wire system that Fiber Optics is replacing. The difference is that Fiber Optics use light pulses to transmit information down fiber lines instead of using electronic pulses to transmit information down copper lines. Looking at the components in a Fiber Optic chain will give a better understanding of how the system works in conjunction with wire based systems.

At one end of the system is a transmitter. This is the place of origin for information coming on to Fiber Optic lines. An injection-laser diode (ILD) can be used for generating the light pulses. Using a lens, the light pulses are funneled into the Fiber Optic medium where they transmit themselves down the line.

Light pulses move easily down the Fiber Optic line because of a principle known as total internal reflection. "This principle of total internal reflection states that when the angle of incidence exceeds a critical value, light cannot get out of the glass; instead, the light bounces back in. When this principle is applied to the construction of the Fiber Optic strand, it is possible to transmit information down fiber lines in the form of light pulses.

There are generally five elements that make up the construction of a Fiber Optic strand, or cable: the optic core, optic cladding, a buffer material, a strength material and the outer jacket (Fig. 1). The optic core is the light-carrying element at the center of the optical fiber. It is commonly made from a combination of silica and germania. Surrounding the core is the optic cladding made of pure silica . It is this combination that makes the principle of total internal reflection possible. The difference in materials used in the making of the core and the cladding creates an extremely reflective surface at the point in which they interface. Light pulses entering the fiber core reflect off the core/cladding interface and thus remain within the core as they move down the line.

Fig. 1. Cut away of a Fiber Optic cable.

Surrounding the cladding is a buffer material used to help shield the core and cladding from damage. A strength material surrounds the buffer, preventing stretch problems when the fiber cable is being pulled. The outer jacket is added to protect against abrasion, solvents, and other contaminants.

Once the light pulses reach their destination they are channeled into the optical receiver. "The basic purpose of an optical receiver is to detect the received light incident on it and to convert it to an electrical signal containing the information impressed on the light at the transmitting end. The electronic information is then ready for input into electronic based communication devices, such as a computer, telephone, or TV.

Fiber-Optic Applications
The use of Fiber Optics was generally not available until 1970 when Corning Glass Works was able to produce a fiber with a loss of 20 dB/km. That is, 1% of the light would remain after traveling 1 km. It was recognized that optical fiber would be feasible for telecommunication transmission only if glass could be developed so pure that attenuation would be 20 dB/km or less. Today's optical fiber attenuation ranges from 0.5 dB/km to 1000 dB/km depending on the optical fiber used. Attenuation limits are based on intended application.

The applications of optical fiber communications have increased at a rapid rate, since the first commercial installation of a Fiber Optic system in 1977. Telephone companies began early on, replacing their old copper wire systems with optical fiber lines. Today's telephone companies use optical fiber throughout their system as the backbone architecture and as the long-distance connection between city phone systems.

Local Area Networks (LAN) is a collective group of computers, or computer systems, connected to each other allowing for shared program software or databases. Colleges, universities, office buildings, and industrial plants, just to name a few, all make use of optical fiber within their LAN systems.

Power companies utilize Fiber Optics in their communication systems and most already have Fiber Optic communication systems in use for monitoring their power grid systems.

Fiber-Optic Advantages
There are several advantages that have been established with the development and implementation of Fiber Optic cable systems. Compared to copper, optical fiber is relatively small in size and light in weight. This characteristic has made it desirable as intra-floor conduits and wiring duct space has become increasing plugged with expanded copper cable installation.

Optical fiber is also desirable because of its electromagnetic immunity. Since Fiber Optics use light to transmit a signal, it is not subject to electromagnetic interference, radio frequency interference, or voltage surges. This may be an important consideration when laying cables near electronic hardware such as computers or industrial equipment. As well, since it does not use electrical impulses, it does not produce electric sparks which can be an obvious fire hazard.
Advances in optical fiber technology have led to decreases in signal loss, or attenuation. As an electric pulse or a light pulse travels down its respective cable line, it will eventually lose signal energy due to imperfections in the transmission medium. To keep the signal going, it must be boosted every so often along the medium line. A signal regenerator is used to boost the electronic pulse in a copper cable. An optical repeater or amplifier is used to boost the light pulse in a Fiber Optic cable. The advantage of optical fiber is that it performs better with respect to attenuation. Fiber-optic cable needs fewer boosting devices, along the same length of line, than copper cable.

A characteristic feature of optical fiber is its wide bandwidth. Bandwidth refers to the amount of information that a fiber can carry. The greater the bandwidth, the greater the carrying capacity of the optical fiber.

Summary
Based on industry activity, it is evident that Fiber Optics has become the industry standard for transmission of telecommunication information. The next progressive step for Fiber Optics is into residential communities also referred to as the "Last Mile", with the ultimate phase of Fiber Optic deployment directly to the home. The choice is not whether to convert to optical fiber, but rather when to convert to optical fiber.