Fiber optic technology and applications

History Of Fiber Optics

The science of fiber optics centers on the transmission of information via light through transparent fibers. This paper explores the history of fiber optics. Included in the discussion is an overview of how fiber optics is used for communication and data transfer. Lastly, the benefits and disadvantages of this technology will be presented.

History of Fiber Optics and its Use for Communication and Data Transfer

Although fiber optics seems to be a wonder of the last few decades, optical communication systems got their start more than two centuries ago. In the 1790s, French engineer Claude Chappe invented the 'optical telegraph'. Chappe's system used a series of semaphores that were mounted on towers, with human operators relaying messages between the towers. However, as Hayes (2005) notes, by the mid-19th century, the electric telegraph had taken over the messaging industry. In 1880, Alexander Graham Bell patented the Photophone, an optical telephone system. The telephone proved to be more practical and the Photophone never became popular.

New technology in the 19th century, based on total internal reflection, would be the technology needed to develop optical transmission of information. Swiss physicist, Daniel Collodon, and French physicist, Jacques Babinet, demonstrated how light could follow jets of water in fountains, in the 1840s. According to Hayes (2005), optical fibers were a critical leap forward in the development of fiber optics. These transparent rods of plastic or glass were patented in the 1920s by Clarence Hansell in the United States and John Logie Baird in England. These were used to transmit television or facsimilie system images. However it wasn't until 1930 that a German medical student, Heinrich Lamm, demonstrated transmitting an image through a bundle of optical fibers inside a body. Jewish, Lamm was forced to move to America as Nazis came into power, and he had to abandon his plans to become a professor of medicine.

The mid 20th century saw continued development in fiber technology. Most development focused on purifying the compound glass that was used for standard optics. In 1970, Corning Glass Works scientists would make a breakthrough for fiber optic technology. They used fused silica for their fibers, resulting in reduced fiber loss. The team of Robert Maurer, Donald Keck and Peter Schultz led to even greater improvements in the technology, including improved manufacturing methods and shifting to longer wavelengths to further improve attenuation (Hayes, 2005)

Today, communication and data transfer is typically conducted with infrared light. The light waves are generated by light-emitting diodes (LEDs) ("Fibre," 2009). To give the least attenuation, wavelengths of 1.3 to 1.6 micrometers are used. If transmission needs to be made more than a few kilometers, semiconductor lasers are employed to boost the light wave strength ("Laser," 2009).

Benefits and Disadvantages of Using Fiber Optics for Communication

There are a variety of benefits and disadvantages to using fiber optics for communication. The primary benefit of fiber optics is its bandwidth capacity. Optical signals have a much greater capacity for information than electrical signals. Scocco (2006) notes that the most advanced copper cables can only carry 1 GB/second. Optical fibers can theoretically carry 350 TB/second (350,000 GB/second). Even though this is a theoretical number, currently telecom carriers are already packing more than 1 TB/second, with a single optical fiber. Currently, using DSL technology, the twisted copper pair is use today can only transmit approximately 50 MB/second. In addition, signal reliability is significantly greater with fiber optics. Lastly, the size and weight of fiber optics is a fraction of that of coaxial cables. Yet, despite these benefits, there are disadvantages to fiber optical cables for communication as well.

Cost is perhaps the largest disadvantage to the use of fiber optics, according to Scocco (2006). Although the amount of traffic on a telecom carrier's backbone justifies the economic investment of fiber optic, running fiber optics to each subscriber's home is still a financial concern. There are also the physical properties of the optical fibers that are a disadvantage at times. Copper cabling is far more flexible than optical fibers. If optical fibers are bent too much, they lose some of their reflective properties. Repair, due to the differences in physical properties, too is not only much simpler with copper wiring but also much less expensive, when compared to optical fibers.