Optical fiber

An optical fiber is a transparent thin fiber, usually made of glass or plastic, for transmitting light. Fiber optics is the branch of science and engineering concerned with such optical fibers.

Disadvantages of optical fibers compared to wires

• High investment cost
• Need for more expensive optical transmitters and receivers
• More difficult and expensive to splice than wires
• At higher optical powers, is susceptible to "fiber fuse" wherein a bit too much light meeting with an imperfection can destroy as much as 1.5 kilometers of wire at several metres per second http://catless.ncl.ac.uk/Risks/12.44.htmlhttp://ol.osa.org/abstract.cfm?id=72607http://www.photonics.com/spectra/tech/XQ/ASP/techid.1576/QX/read.htmhttp://www.furukawa.co.jp/review/fr024/fr24_04.pdf . A "Fiber fuse" protection device at the transmitter can break the circuit to prevent damage, if the extreme conditions for this are deemed possible.
• Cannot carry electrical power to operate terminal devices. However, current telecommunication trends greatly reduce this concern: availability of cell phones and wireless PDAs; the routine inclusion of back-up batteries in communication devices; lack of real interest in hybrid metal-fiber cables; and increased use of fiber-based intermediate systems.

Almost all these disadvantages have been surmounted or bypassed in contemporary telecommunications usage, and communication systems are now unthinkable without fiber optics. Their cost is much more economic than old coaxial cables because the transmitters and receivers (laser and photodiodes) turn out cheaper than electric circuitry as their capacity is much superior. The cost of regeneration in electrical long distance transmission systems is completely impractical for modern communications.

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