Introduction to Fiber Optics

BY: Christina Hansen


During our current age, the increasing ability to transmit more information over longer distances more quickly has expanded the boundaries of our technological development in many areas such as data networks, wireless and satellite communications, cable operators, and broadcasters.

All of this has become possible by the use of fiber optics, and as technology demands insist upon improved performance, fiber optics will continue to increase.

What are Fiber Optics?

Fiber Optics, also called optical fibers, are microscopic strands of very pure glass with about the same diameter of a human hair. Thousands of these optical fibers are arranged in bundles in optical cables and are used to transmit light signals over long distances. The bundles are protected by a jacket, which is the cable's outer covering.

The single optical fiber consists of the core which is the thin glass center of the fiber where the light travels, the outer optical material that surrounds the core and reflects the light back into it is the cladding, and the plastic coating that protects the fiber from moisture and damage is the buffer coating.

Single-mode and multi-mode are the two types of optical fibers. The single-mode, used for long distances, has small cores and transmits infrared laser light. The multi-mode, normally used for short distances, has large cores and transmits infrared light.

Fiber Optics versus Copper

Even though the fiber optic system is similar to the copper wire system, fiber optics are steadily replacing copper wires today as an appropriate means of communication signal transmission.

Some advantages fiber optics have over copper are the dollar savings because they are less expensive, fiber optics are thinner, and they have a higher carrying capacity. Optical fibers are well suited for carrying digital information. There's no electricity so the danger of fire is reduced. Fiber optic cables are lightweight, take up less space, and are also flexible.

History of Fiber Optics

Fiber optics go back as far as Roman times, but the first was an "optical telegraph," which allowed operators to relay a message from one tower to the next by a series of lights mounted on the towers. This was invented in the 1790s by the French Chappe brothers. Great achievement was made in optical science over the course of the next century.

Fiber Optics during the 1800s

Physicists Daniel Collodon and Jacques Babinet reported in the 1840s that light could be directed along jets of water for fountain displays. In 1854, John Tyndall, a British physicist, demonstrated that light could travel through water jets, thereby proving that a light signal could be bent.

In 1880, Alexander Graham Bell patented an optical telephone system which assisted in the advancement of optical technology. Also in 1880, William Wheeler invented a system of light pipes that illuminated homes from an electric arch lamp located in the basement.

Bent glass rods were used to illuminate body cavities in 1888 by Dr. Roth and Professor Reuss of Vienna. Henry Saint-Rene designed a system of bent glass rods to guide light images in an early television scheme in 1895. A patent was applied for by an American, David Smith, in 1898 for a dental illuminator using a curved glass rod.

Fiber Optics Move Forward in the 1900s

The first person to transmit an image of a light bulb filament through a bundle of optical fibers was Heinrich Lamm in 1930. Then, Holger Moller Hansen applied for a Danish patent in 1951 on fiber-optic imaging in which he proposed cladding glass or plastic fibers with a transparent low-index material, but was denied because of the Baird and Hansell patents in 1926.

An undergraduate student named Larry Curtiss was hired by Basil Hirschowitz and C. Wilbur Peters in 1955 to work on their fiber-optic endoscope project. In 1956, Curtiss made the first glass-clad fibers by rod-in-tube method. And in 1957, Hirschowitz was the first to test fiber-optic endoscope on a patient.

Elias Snitzer of American Optical published a theoretical description of single mode fibers in 1961. In 1970, the scientists at Corning Glass Works reached their goal of making single mode fibers with attenuation less then 20dB/km. They achieved this through doping silica glass with titanium.

In 1973, Bell Laboratories developed a modified chemical vapor deposition process that heated chemical vapors and oxygen to form ultra-transparent glass that can be mass-produced into low-loss optical fiber. This process still remains the standard for fiber-optic cable manufacturing.

The Dorset (UK) police installed the first non-experimental fiber-optic link in 1975, and the first live telephone traffic through fiber optics occurred in Long Beach, California two years later.

In the late 1970s and early 1980s, telephone companies used great numbers of fibers to rebuild their communications infrastructure. In the mid-1980s, Sprint was founded on the first nationwide, 100 percent, fiber-optic network.

In 1991, Desurvire and Payne demonstrated optical amplifiers that were built into the fiber-optic cable itself. The all-optic system could carry 100 times more information than cable with electronic amplifiers.

The first all-optic fiber cable called TPC-5, which used optical amplifiers, was laid across the Pacific Ocean in 1996. In 1997, the Fiber Optic Link Around the Globe (FLAG) became the longest single-cable network in the world and furnished the groundwork for the next generation of Internet applications.

Today, the medical, military, telecommunication, industrial, data storage, networking, and broadcast industries are able to implement and use fiber optic technology in a variety of applications.




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