An optical fiber (or fibre in British English) is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to transmit light[a] between the two ends of the fiber and find wide usage in fiber-optic communications, where they permit transmission over longer distances and at higher bandwidths (data transfer rates) than electrical cables. Fibers are used instead of metal wires because signals travel along them with less loss; in addition, fibers are immune to electromagnetic interference, a problem from which metal wires suffer. Fibers are also used for illumination and imaging, and are often wrapped in bundles so they may be used to carry light into, or images out of confined spaces, as in the case of a fiberscope. Specially designed fibers are also used for a variety of other applications, some of them being fiber optic sensors and fiber lasers.
Optical fibers typically include a core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by the phenomenon of total internal reflection which causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers, while those that support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,000 meters (3,300 ft).
Being able to join optical fibers with low loss is important in fiber optic communication. This is more complex than joining electrical wire or cable and involves careful cleaving of the fibers, precise alignment of the fiber cores, and the coupling of these aligned cores. For applications that demand a permanent connection a fusion splice is common. In this technique, an electric arc is used to melt the ends of the fibers together. Another common technique is a mechanical splice, where the ends of the fibers are held in contact by mechanical force. Temporary or semi-permanent connections are made by means of specialized optical fiber connectors.
The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. The term was coined by Indian-American physicist Narinder Singh Kapany, who is widely acknowledged as the father of fiber optics.
Lincolnshire (abbreviated Lincs.) is a county in the East Midlands of England, with a long coastline on the North Sea to the east. It borders Norfolk to the south-east, Cambridgeshire to the south, Rutland to the south-west, Leicestershire and Nottinghamshire to the west, South Yorkshire to the north-west, and the East Riding of Yorkshire to the north. It also borders Northamptonshire in the south for just 20 yards (19 m), England's shortest county boundary. The county town is the city of Lincoln, where the county council has its headquarters.
The ceremonial county of Lincolnshire consists of the non-metropolitan county of Lincolnshire and the area covered by the unitary authorities of North Lincolnshire and North East Lincolnshire. Part of the ceremonial county is in the Yorkshire and the Humber region of England, and most is in the East Midlands region. The county is the second-largest of the English ceremonial counties and one that is predominantly agricultural in land use. The county is fourth-largest of the two-tier counties, as the unitary authorities of North Lincolnshire and North East Lincolnshire are not included.
The county has several geographical sub-regions, including the rolling chalk hills of the Lincolnshire Wolds. In the south-east are the Lincolnshire Fens (south-east Lincolnshire), the Carrs (similar to the Fens but in north Lincolnshire), the industrial Humber Estuary and North Sea coast around Grimsby and Scunthorpe, and in the south-west of the county, the Kesteven Uplands, rolling limestone hills in the district of South Kesteven.