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.
Ipswich (/ˈɪpswɪtʃ/ (About this soundlisten)) is a historic county town in Suffolk, England. The town is located in East Anglia about 10 miles away from the mouth of the River Orwell and the North Sea. Ipswich is both on the Great Eastern Main Line railway and the A12 road, it is 66 miles (106 km) north-east of London, 54 miles (89 km) east-southeast of Cambridge, and 45 miles (72 km) south of Norwich. Ipswich is surrounded by two Areas of Outstanding Natural Beauty (AONB); Suffolk Coast and Heaths and Dedham Vale.
Ipswich's modern name is derived from the medieval name Gippeswic, likely taken either from an Old Saxon personal name or from an earlier name given to the Orwell Estuary (although unrelated to the name of the River Gipping). It has also been known as Gyppewicus and Yppswyche. The town has been continuously occupied since the Saxon period, and is contested to be one of the oldest towns in the United Kingdom. Ipswich was a settlement of great economic importance to England throughout its history, particularly in trade. The town's historical dock, present-day Ipswich Waterfront, was known as the largest and most important dock in the kingdom.
Ipswich is a non-metropolitan district and is a large settlement despite its town status. The urban development of Ipswich overspills the borough boundaries significantly, with 75% of the town's population living within the borough at the time of the 2011 Census, when it was the fourth-largest urban area in the United Kingdom's East of England region, and the 42nd-largest urban area in England and Wales. In 2011, the town of Ipswich was found to have a population of 133,384, while the Ipswich built-up area is estimated to have a population of approximately 180,000 in 2011.
The town is split into various quarters, with central and the waterfront drawing the most footfall. Central is home to the town's retail shopping and the historical town square, the Cornhill. The waterfront is located south of the town centre on the bend of the River Orwell and is a picturesque setting housing the town's impressive marina. The waterfront was historically an industrial port but has since been transformed into a trendy area lined with high-rise apartment buildings, restaurants, bars and cafés. The waterfront is also home to one of the UK's newest universities, the University of Suffolk, which was formed in 2016.
Ipswich has become a tourist hotspot in the UK with 3.5 million people reported to have visited the county town in 2016. In 2020, Ipswich was ranked as an emerging global tourist destination by TripAdvisor. Ipswich was voted as the 7th most desirable place to live and work in England by the Royal Mail in 2017. In 2007, Ipswich was awarded the cleanest town award, and in 2015, Ipswich was rated as the third happiest place to live in the UK.