History and Advantages of Fiber Optics

In 1880 Alexander Graham Bell invented the photophone. Bell considered this a greater discovery than his other invention, the telephone. With the photophone, Bell would speak into a microphone, which would then cause a mirror to vibrate. The sun's light would strike the mirror, and the vibration of the mirror would transmit light across an open distance of about 656ft (200m). The receiver's mirror would receive the light and cause a selenium crystal to vibrate, causing the noise to come out on the other end. Although the photophone was successful in allowing conversation over an open space, it had a few drawbacks: it did not work at night, in the rain or if someone walked between the signal and receiver. Eventually, Bell gave up on this idea.

It was not until the 1950s that the laser was invented. This device was a finely controlled beam of light that could transmit information over long distances. Unfortunately, the same drawbacks experienced by Alexander Graham Bell also plagued the laser. Although it could be used at night, it did not work during rain, fog or at any time a building was erected between the sender and the receiver.

Dr. Robert Maurer, Peter Schultz and Donald Keck of Corning Incorporated in Corning, New York, came up with the first low loss optical fiber, with less than 20dB/km (decibels per kilometer) loss. Today, single-mode, premium grade fiber is sold with specifications of 0.25 dB/km or better.

In 1977 Corning joined forces with another technological giant, Siemens Corporation, to form Siecor. Corning's extensive work with fiber, coupled with Siemen's cabling technology, helped launch a new era in optical fiber cable and associated products. Today, Siecor is a world leader in the manufacturing of fiber optic cabling system products for voice, data and video communications applications.

In its simplest form fiber optics is a medium for carrying information from one point to another in the form of light. Unlike the copper form of transmission, fiber optics is not electrical in nature. A basic fiber optic system consists of 1) a transmitting device, which generates the light signal 2) an optical fiber cable, which carries the light and 3) a receiver, which accepts the light signal transmitted. The fiber itself is passive and does not contain any active, generative properties.

Fiber systems have many advantages over copper-based communications systems.
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1. Long Distance Signal Transmission 

The low attenuation and superior signal integrity found in optical systems allow much longer intervals of signal transmission than copper-based systems. While single-line, voice-grade copper systems longer than a couple of kilometers (1.2 miles) require in-line signal repeaters for satisfactory performance; it is not unusual for fiber optic systems to span over 100 kilometers or about 62 miles, with no active or passive processing. Emerging technologies promise even greater distances in the future. 

2. Large Bandwidth, Light Weight, Small Diameter 

While today's applications require an ever-increasing amount of bandwidth, it is important to consider the space constraints on many end users. It is commonplace to install new cabling within existing duct systems. The relatively small diameter and light weight of fiber cables make such installations easy and practical and saves valuable conduit space in these environments. 

3. Long Lengths 

Long, continuous lengths also provide advantages for installers and end users. Small diameters make it practical to manufacture and install much longer lengths than for copper cables. In fact 12 kilometer continuous fiber optic cable lengths are common. Multimode cable lengths can be four kilometers or more, although most standards require a maximum length of 2km or less. Multimode cable lengths are based on industry demand. 

4. Easy Installation and Upgrades 

Long lengths make fiber optic cable installation much easier and less expensive. Optical fiber cables can be installed with the same equipment used to install copper and coaxial cables, with some modifications due to the small size and limited pull tension and bend radius of optical cables. Optical cables can typically be installed in duct systems in spans of 6,000 meters or more depending on the duct's condition, layout of the duct system and installation technique. The longer cables can be coiled at an intermediate point and pulled further into the duct system as necessary. System designers typically plan optical systems to will meet the growth needs for 15 to 20 year span. Although sometimes difficult to predict, growth can be accommodated by installing spare fibers for future requirements. Installation of spare fibers today is more economical than installing additional cables later. 

5. Non-Conductivity 

Another advantage of fiber cables is their dielectric nature. Since fiber has no metallic components, it can be installed in areas with electromagnetic interference (EMI), including radio frequency interference (RFI). Areas with high EMI include utility lines, power-carrying lines and railroad tracks. All dielectric cables are also ideal for areas of high lightning strike incidence. 

6. Security 

Unlike copper-based systems, the dielectric nature of optical fiber makes it impossible to remotely detect the signal being transmitted within the cable. The only way to do so is by actually accessing the fiber optic cable itself. However, accessing the fiber requires the intervention that is easily detectable by security surveillance. These circumstances make fiber extremely attractive for use in governmental institutions, finance/banking and other environments with major security concerns.