A cable reel trailer with conduit that can carry optical fiber

 

Multi-mode optical fiber in an underground service pit

Main articles: Optical fiber and Optical fiber cable

An optical fiber cable consists of a core, cladding, and a buffer , in which the cladding guides the light along the core by using the method of total internal reflection. The core and the cladding  are usually made of high-quality silica glass, although they can both be made of plastic as well. Connecting two optical fibers is done by fusion splicing or mechanical splicing and requires special skills and interconnection technology due to the microscopic precision required to align the fiber cores.

 

Two main types of optical fiber used in optic communications include multi-mode optical fibers and single-mode optical fibers. A multi-mode optical fiber has a larger core , allowing less precise, cheaper transmitters and receivers to connect to it as well as cheaper connectors. However, a multi-mode fiber introduces multimode distortion, which often limits the bandwidth and length of the link. Furthermore, because of its higher dopant content, multi-mode fibers are usually expensive and exhibit higher attenuation. The core of a single-mode fiber is smaller  and requires more expensive components and interconnection methods, but allows much longer, higher-performance links.

 

In order to package fiber into a commercially viable product, it typically is protectively coated by using ultraviolet , light-cured acrylate polymers, then terminated with optical fiber connectors, and finally assembled into a cable. After that, it can be laid in the ground and then run through the walls of a building and deployed aerially in a manner similar to copper cables. These fibers require less maintenance than common twisted pair wires, once they are deployed.

 

Specialized cables are used for long distance subsea data transmission, e.g. transatlantic communications cable. New  cables operated by commercial enterprises  typically have four strands of fiber and cross the Atlantic in 60-70ms. Cost of each such cable was about $300M in 2011. source: The Chronicle Herald.

 

Another common practice is to bundle many fiber optic strands within long-distance power transmission cable. This exploits power transmission rights of way effectively, ensures a power company can own and control the fiber required to monitor its own devices and lines, is effectively immune to tampering, and simplifies the deployment of smart grid technology.