title: Aachen

text: On 9 February 1801, the Peace of Lunéville removed the ownership of Aachen and the entire "left bank" of the Rhine from Germany (the Holy Roman Empire) and granted it to France. In 1815, control of the town was passed to the Kingdom of Prussia through an agreement reached by the Congress of Vienna. The third congress took place in 1818, to decide the fate of occupied Napoleonic France.


title: Aachen

text: By the middle of the 19th century, industrialisation had swept away most of the city's medieval rules of production and commerce, although the entirely corrupt remains of the city's medieval constitution were kept in place (compare the famous remarks of Georg Forster in his "Ansichten vom Niederrhein") until 1801, when Aachen became the "chef-lieu du département de la Roer" in Napoleon's First French Empire. In 1815, after the Napoleonic Wars, the Kingdom of Prussia took over within the new German Confederation. The city was one of its most socially and politically backward centres until the end of the 19th century. Administered within the Rhine Province, by 1880 the population was 80,000. Starting in 1838, the railway from Cologne to Belgium passed through Aachen. The city suffered extreme overcrowding and deplorable sanitary conditions until 1875, when the medieval fortifications were finally abandoned as a limit to building and new, better housing was built in the east of the city, where sanitary drainage was easiest. In December 1880, the Aachen tramway network was opened, and in 1895 it was electrified. In the 19th century and up to the 1930s, the city was important in the production of railway locomotives and carriages, iron, pins, needles, buttons, tobacco, woollen goods, and silk goods.


title: Aachen

text: After World War I, Aachen was occupied by the Allies until 1930, along with the rest of German territory west of the Rhine. Aachen was one of the locations involved in the ill-fated Rhenish Republic. On 21 October 1923, an armed mob took over the city hall. Similar actions took place in Mönchen-Gladbach, Duisburg, and Krefeld. This republic lasted only about a year. Aachen was heavily damaged during World War II. According to Jörg Friedrich in "The Fire" (2008), two Allied air raids on 11 April and 24 May 1944 "radically destroyed" the city. The first killed 1,525, including 212 children, and bombed six hospitals. During the second, 442 aircraft hit two railway stations, killed 207, and left 15,000 homeless. The raids also destroyed Aachen-Eilendorf and Aachen-Burtscheid.


title: Aachen

text: The city and its fortified surroundings were laid siege to from 12 September to 21 October 1944 by the US 1st Infantry Division with the 3rd Armored Division assisting from the south. Around 13 October the US 2nd Armored Division played their part, coming from the north and getting as close as Würselen, while the 30th Infantry Division played a crucial role in completing the encirclement of Aachen on 16 October 1944. With reinforcements from the US 28th Infantry Division the Battle of Aachen continued involving direct assaults through the heavily defended city, which finally forced the German garrison to surrender on 21 October 1944.


title: Aachen

text: Aachen was the first German city to be captured by the Western Allies, and its residents welcomed the soldiers as liberators. What remained of the city was destroyed—in some areas completely—during the fighting, mostly by American artillery fire and demolitions carried out by the Waffen-SS defenders. Damaged buildings included the medieval churches of St. Foillan, St. Paul and St. Nicholas, and the Rathaus (city hall), although Aachen Cathedral was largely unscathed. Only 4,000 inhabitants remained in the city; the rest had followed evacuation orders. Its first Allied-appointed mayor, Franz Oppenhoff, was assassinated by an SS commando unit.


title: Aachen

text: During the Roman period, Aachen was the site of a flourishing Jewish community. Later, during the Carolingian empire, a Jewish community lived near the royal palace. In 797, Isaac, a Jewish merchant, accompanied two ambassadors of Charlemagne to the court of Harun al-Rashid. He returned to Aachen in July 802, bearing an elephant called "Abul-Abbas" as a gift for the emperor. During the 13th century, many Jews converted to Christianity, as shown in the records of the Aachen Minster (today's Cathedral). In 1486, the Jews of Aachen offered gifts to Maximilian I during his coronation ceremony. In 1629, the Aachen Jewish community was expelled from the city. In 1667, six Jews were allowed to return. Most of the Aachen Jews settled in the nearby town of Burtscheid. On 16 May 1815, the Jewish community of the city offered an homage in its synagogue to the Prussian king, Friedrich Wilhelm III. A Jewish cemetery was acquired in 1822. 1,345 Jews lived in the city in 1933. The synagogue was destroyed during "Kristallnacht" in 1938. In 1939, after emigration and arrests, 782 Jews remained in the city. After World War II, only 62 Jews lived there. In 2003, 1,434 Jews were living in Aachen. In Jewish texts, the city of Aachen was called "Aish" or "Ash" (אש).


title: Aachen

text: The city of Aachen has developed into a technology hub as a by-product of hosting one of the leading universities of technology in Germany with the RWTH Aachen (Rheinisch-Westfälische Technische Hochschule), known especially for mechanical engineering, automotive and manufacturing technology as well as for its research and academic hospital Klinikum Aachen, one of the largest medical facilities in Europe.


title: Aachen

text: Aachen is located in the middle of the Meuse–Rhine Euroregion, close to the border tripoint of Germany, the Netherlands, and Belgium. The town of Vaals in the Netherlands lies nearby at about from Aachen's city centre, while the Dutch city of Heerlen and Eupen, the capital of the German-speaking Community of Belgium, are both located about from Aachen city centre. Aachen lies near the head of the open valley of the Wurm (which today flows through the city in canalised form), part of the larger basin of the Meuse, and about north of the High Fens, which form the northern edge of the Eifel uplands of the Rhenish Massif.


title: Aachen

text: The maximum dimensions of the city's territory are from north to south, and from east to west. The city limits are long, of which border Belgium and the Netherlands. The highest point in Aachen, located in the far southeast of the city, lies at an elevation of above sea level. The lowest point, in the north, and on the border with the Netherlands, is at .


title: Aachen

text: As the westernmost city in Germany (and close to the Low Countries), Aachen and the surrounding area belongs to a temperate climate zone (Cfb), with humid weather, mild winters, and warm summers. Because of its location north of the Eifel and the High Fens and its subsequent prevailing westerly weather patterns, rainfall in Aachen (on average 805 mm/year) is comparatively higher than, for example, in Bonn (with 669 mm/year). Another factor in the local weather forces of Aachen is the occurrence of Foehn winds on the southerly air currents, which results from the city's geographic location on the northern edge of the Eifel.


title: Aachen

text: Because the city is surrounded by hills, it suffers from inversion-related smog. Some areas of the city have become urban heat islands as a result of poor heat exchange, both because of the area's natural geography and from human activity. The city's numerous cold air corridors, which are slated to remain as free as possible from new construction, therefore play an important role in the urban climate of Aachen.


title: Aachen

text: The geology of Aachen is very structurally heterogeneous. The oldest occurring rocks in the area surrounding the city originate from the Devonian period and include carboniferous sandstone, greywacke, claystone and limestone. These formations are part of the Rhenish Massif, north of the High Fens. In the Pennsylvanian subperiod of the Carboniferous geological period, these rock layers were narrowed and folded as a result of the Variscan orogeny. After this event, and over the course of the following 200 million years, this area has been continuously flattened.


title: Aachen

text: During the Cretaceous period, the ocean penetrated the continent from the direction of the North Sea up to the mountainous area near Aachen, bringing with it clay, sand, and chalk deposits. While the clay (which was the basis for a major pottery industry in nearby Raeren) is mostly found in the lower areas of Aachen, the hills of the Aachen Forest and the Lousberg were formed from upper Cretaceous sand and chalk deposits. More recent sedimentation is mainly located in the north and east of Aachen and was formed through tertiary and quaternary river and wind activities.


title: Aachen

text: Along the major thrust fault of the Variscan orogeny, there are over 30 thermal springs in Aachen and Burtscheid. Additionally, the subsurface of Aachen is traversed by numerous active faults that belong to the Rurgraben fault system, which has been responsible for numerous earthquakes in the past, including the 1756 Düren earthquake and the 1992 Roermond earthquake, which was the strongest earthquake ever recorded in the Netherlands.


title: Aachen

text: Aachen has 245,885 inhabitants (as of 31 December 2015), of whom 118,272 are female, and 127,613 are male.


title: Aachen

text: The unemployment rate in the city is, as of April 2012, 9.7 percent. At the end of 2009, the foreign-born residents of Aachen made up 13.6 percent of the total population. A significant portion of foreign residents are students at the RWTH Aachen University.


title: Aachen

text: The city is divided into seven administrative districts, or boroughs, each with its own district council, district leader, and district authority. The councils are elected locally by those who live within the district, and these districts are further subdivided into smaller sections for statistical purposes, with each sub-district named by a two-digit number.


title: Aachen

text: Regardless of official statistical designations, there are 50 neighbourhoods and communities within Aachen, here arranged by district:


title: Aachen

text: Herzogenrath, Würselen, Eschweiler, Stolberg and Roetgen (which are all in the district of Aachen); Raeren, Kelmis and Plombières (Liège Province in Belgium) as well as Vaals, Gulpen-Wittem, Simpelveld, Heerlen and Kerkrade (all in Limburg Province in the Netherlands).


title: Aachen

text: The current Mayor of Aachen is Sibylle Keupen, an independent endorsed by Alliance 90/The Greens, since 2020. The most recent mayoral election was held on 13 September 2020, with a runoff held on 27 September, and the results were as follows:


title: Aachen

text: The Aachen city council governs the city alongside the Mayor. The most recent city council election was held on 13 September 2020, and the results were as follows:


title: Aachen

text: Aachen Cathedral was erected on the orders of Charlemagne. Construction began "c." AD 796, and it was, on completion "c." 798, the largest cathedral north of the Alps. It was modelled after the Basilica of San Vitale, in Ravenna, Italy, and was built by Odo of Metz. Charlemagne also desired for the chapel to compete with the Lateran Palace, both in quality and authority. It was originally built in the Carolingian style, including marble covered walls, and mosaic inlay on the dome. On his death, Charlemagne's remains were interred in the cathedral and can be seen there to this day. The cathedral was extended several times in later ages, turning it into a curious and unique mixture of building styles. The throne and gallery portion date from the Ottonian, with portions of the original opus sectile floor still visible. The 13th century saw gables being added to the roof, and after the fire of 1656, the dome was rebuilt. Finally, a choir was added around the start of the 15th century.


title: Aachen

text: After Frederick Barbarossa canonised Charlemagne in 1165 the chapel became a destination for pilgrims. For 600 years, from 936 to 1531, Aachen Cathedral was the church of coronation for 30 German kings and 12 queens. The church built by Charlemagne is still the main attraction of the city. In addition to holding the remains of its founder, it became the burial place of his successor Otto III. In the upper chamber of the gallery, Charlemagne's marble throne is housed. Aachen Cathedral has been designated as a UNESCO World Heritage Site.


title: Aachen

text: Most of the marble and columns used in the construction of the cathedral were brought from Rome and Ravenna, including the sarcophagus in which Charlemagne was eventually laid to rest. A bronze bear from Gaul was placed inside, along with an equestrian statue from Ravenna, believed to be Theodric, in contrast to a wolf and a statue of Marcus Aurelius in the Capitoline. Bronze pieces such as the doors and railings, some of which have survived to present day, were cast in a local foundry. Finally, there is uncertainty surrounding the bronze pine cone in the chapel, and where it was created. Wherever it was made, it was also a parallel to a piece in Rome, this in Old St. Peter's Basilica.


title: Aachen

text: Aachen Cathedral Treasury has housed, throughout its history, a collection of liturgical objects. The origin of this church treasure is in dispute as some say Charlemagne himself endowed his chapel with the original collection, while the rest were collected over time. Others say all of the objects were collected over time, from such places as Jerusalem and Constantinople. The location of this treasury has moved over time and was unknown until the 15th century when it was located in the Matthiaskapelle (St. Matthew's Chapel) until 1873, when it was moved to the Karlskapelle (Charles' Chapel). From there it was moved to the Hungarian Chapel in 1881 and in 1931 to its present location next to the Allerseelenkapelle (Poor Souls' Chapel). Only six of the original Carolingian objects have remained, and of those only three are left in Aachen: the Aachen Gospels, a diptych of Christ, and an early Byzantine silk. The Coronation Gospels and a reliquary burse of St. Stephen were moved to Vienna in 1798 and the Talisman of Charlemagne was given as a gift in 1804 to Josephine Bonaparte and subsequently to Rheims Cathedral. 210 documented pieces have been added to the treasury since its inception, typically to receive in return legitimisation of linkage to the heritage of Charlemagne. The Lothar Cross, the Gospels of Otto III and multiple additional Byzantine silks were donated by Otto III. Part of the Pala d'Oro and a covering for the Aachen Gospels were made of gold donated by Henry II. Frederick Barbarossa donated the candelabrum that adorns the dome and also once "crowned" the Shrine of Charlemagne, which was placed underneath in 1215. Charles IV donated a pair of reliquaries. Louis XI gave, in 1475, the crown of Margaret of York, and, in 1481, another arm reliquary of Charlemagne. Maximilian I and Charles V both gave numerous works of art by Hans von Reutlingen. Continuing the tradition, objects continued to be donated until the present, each indicative of the period of its gifting, with the last documented gift being a chalice from 1960 made by Ewald Mataré.


title: Aachen

text: The Aachen Rathaus, (English: Aachen City Hall or Aachen Town Hall) dated from 1330, lies between two central squares, the "Markt" (marketplace) and the "Katschhof" (between city hall and cathedral). The coronation hall is on the first floor of the building. Inside one can find five frescoes by the Aachen artist Alfred Rethel which show legendary scenes from the life of Charlemagne, as well as Charlemagne's signature. Also, precious replicas of the Imperial Regalia are kept here.


title: Aachen

text: Since 2009, the city hall has been a station on the "Route Charlemagne", a tour programme by which historical sights of Aachen are presented to visitors. At the city hall, a museum exhibition explains the history and art of the building and gives a sense of the historical coronation banquets that took place there. A portrait of Napoleon from 1807 by Louis-André-Gabriel Bouchet and one of his wife Joséphine from 1805 by Robert Lefèvre are viewable as part of the tour.


title: Aachen

text: As before, the city hall is the seat of the mayor of Aachen and of the city council, and annually the Charlemagne Prize is awarded there.


title: Aachen

text: The "Grashaus", a late medieval house at the "Fischmarkt", is one of the oldest non-religious buildings in central Aachen. It hosted the city archive, and before that, the Grashaus was the city hall until the present building took over this function.


title: Aachen

text: The "Elisenbrunnen" is one of the most famous sights of Aachen. It is a neo-classical hall covering one of the city's famous fountains. It is just a minute away from the cathedral. Just a few steps in a south-easterly direction lies the 19th-century theatre.


title: Aachen

text: Also of note are two remaining city gates, the "Ponttor" (Pont gate), northwest of the cathedral, and the "Marschiertor" (marching gate), close to the central railway station. There are also a few parts of both medieval city walls left, most of them integrated into more recent buildings, but some others still visible. There are even five towers left, some of which are used for housing.


title: Aachen

text: St. Michael's Church, Aachen was built as a church of the Aachen Jesuit Collegium in 1628. It is attributed to the Rhine mannerism, and a sample of a local Renaissance architecture. The rich façade remained unfinished until 1891, when the architect Peter Friedrich Peters added to it. The church is a Greek Orthodox church today, but the building is used also for concerts because of its good acoustics.


title: Aachen

text: The synagogue in Aachen, which was destroyed on the Night of Broken Glass (Kristallnacht), 9 November 1938, was reinaugurated on 18 May 1995. One of the contributors to the reconstructions of the synagogue was Jürgen Linden, the Lord Mayor of Aachen from 1989 to 2009.


title: Aachen

text: There are numerous other notable churches and monasteries, a few remarkable 17th- and 18th-century buildings in the particular Baroque style typical of the region, a synagogue, a collection of statues and monuments, park areas, cemeteries, among others. Among the museums in the town are the Suermondt-Ludwig Museum, which has a fine sculpture collection and the Aachen Museum of the International Press, which is dedicated to newspapers from the 16th century to the present. The area's industrial history is reflected in dozens of 19th- and early 20th-century manufacturing sites in the city.


title: Aachen

text: Aachen is the administrative centre for the coal-mining industries in neighbouring places to the northeast.


title: Aachen

text: Products manufactured in Aachen include electrical goods, fine woolen textiles, foodstuffs (chocolate and candy), glass, machinery, rubber products, furniture, metal products. Also in and around Aachen chemicals, plastics, cosmetics, and needles and pins are produced. Though once a major player in Aachen's economy, today glassware and textile production make up only 10% of total manufacturing jobs in the city. There have been a number of spin-offs from the university's IT technology department.


title: Aachen

text: In June 2010, Achim Kampker, together with Günther Schuh, founded a small company to develop Street Scooter GmbH; in August 2014, it was renamed StreetScooter GmbH. This was a privately organised research initiative at the RWTH Aachen University which later became an independent company in Aachen. Kampker was also the founder and chairman of the European Network for Affordable and Sustainable Electromobility. In May 2014, the company announced that the city of Aachen, the city council Aachen and the savings bank Aachen had ordered electric vehicles from the company. In late 2014, approximately 70 employees were manufacturing 200 vehicles annually in the premises of the Waggonfabrik Talbot, the former Talbot/Bombardier plant in Aachen.


title: Aachen

text: In December 2014 Deutsche Post DHL Group purchased the StreetScooter company, which became its wholly owned subsidiary. By April 2016, the company announced that it would produce 2000 of its electric vans branded "Work" in Aachen by the end of the year.


title: Aachen

text: In 2015, the electric vehicle start-up e.GO Mobile was founded by Günther Schuh, which started producing the e.GO Life electric passenger car and other vehicles in April 2019.


title: Aachen

text: In April 2016, StreetScooter GmbH announced that it would be scaling up to manufacture approximately 10,000 of the "Work" vehicles annually, starting in 2017, also in Aachen. If that goal is achieved, it will become the largest electric light utility vehicle manufacturer in Europe, surpassing Renault which makes the smaller "Kangoo Z.E.".


title: Aachen

text: RWTH Aachen University, established as Polytechnicum in 1870, is one of Germany's Universities of Excellence with strong emphasis on technological research, especially for electrical and mechanical engineering, computer sciences, physics, and chemistry. The university clinic attached to the RWTH, the Klinikum Aachen, is the biggest single-building hospital in Europe. Over time, a host of software and computer industries have developed around the university. It also maintains a botanical garden (the Botanischer Garten Aachen).


title: Aachen

text: FH Aachen, Aachen University of Applied Sciences (AcUAS) was founded in 1971. The AcUAS offers a classic engineering education in professions such as mechatronics, construction engineering, mechanical engineering or electrical engineering. German and international students are educated in more than 20 international or foreign-oriented programmes and can acquire German as well as international degrees (Bachelor/Master) or "Doppelabschlüsse" (double degrees). Foreign students account for more than 21% of the student body.


title: Aachen

text: The Katholische Hochschule Nordrhein-Westfalen – Abteilung Aachen (Catholic University of Applied Sciences Northrhine-Westphalia – Aachen department) offers its some 750 students a variety of degree programmes: social work, childhood education, nursing, and co-operative management. It also has the only programme of study in Germany especially designed for mothers.


title: Aachen

text: The Hochschule für Musik und Tanz Köln (Cologne University of Music) is one of the world's foremost performing arts schools and one of the largest music institutions for higher education in Europe with one of its three campuses in Aachen. The Aachen campus substantially contributes to the Opera/Musical Theatre master's programme by collaborating with the Theater Aachen and the recently established musical theatre chair through the Rheinische Opernakademie.


title: Aachen

text: The annual CHIO (short for the French term "Concours Hippique International Officiel") is the biggest equestrian meeting of the world and among horsemen is considered to be as prestigious for equitation as the tournament of Wimbledon for tennis. Aachen hosted the 2006 FEI World Equestrian Games.


title: Aachen

text: The local football team Alemannia Aachen had a short run in Germany's first division, after its promotion in 2006. However, the team could not sustain its status and is now back in the fourth division. The stadium "Tivoli", opened in 1928, served as the venue for the team's home games and was well known for its incomparable atmosphere throughout the whole of the second division. Before the old stadium's demolition in 2011, it was used by amateurs, whilst the Bundesliga Club held its games in the new stadium "Neuer Tivoli" – meaning New Tivoli—a couple of metres down the road. The building work for the stadium which has a capacity of 32,960, began in May 2008 and was completed by the beginning of 2009.


title: Aachen

text: The Ladies in Black women's volleyball team (part of the "PTSV Aachen" sports club since 2013) has played in the first German volleyball league (DVL) since 2008.


title: Aachen

text: Aachen's railway station, the Hauptbahnhof (Central Station), was constructed in 1841 for the Cologne–Aachen railway line. In 1905, it was moved closer to the city centre. It serves main lines to Cologne, Mönchengladbach and Liège as well as branch lines to Heerlen, Alsdorf, Stolberg and Eschweiler. ICE high speed trains from Brussels via Cologne to Frankfurt am Main and Thalys trains from Paris to Cologne also stop at Aachen Central Station. Four RE lines and two RB lines connect Aachen with the Ruhrgebiet, Mönchengladbach, Spa (Belgium), Düsseldorf and the Siegerland. The "Euregiobahn", a regional railway system, reaches several minor cities in the Aachen region.


title: Aachen

text: There are four smaller stations in Aachen: "Aachen West", "Aachen Schanz", "Aachen-Rothe Erde" and "Eilendorf". Slower trains stop at these. Aachen West has gained in importance with the expansion of RWTH Aachen University.


title: Aachen

text: There are two stations for intercity bus services in Aachen: Aachen West station, in the north-west of the city, and Aachen Wilmersdorfer Straße, in the north-east.


title: Aachen

text: The first horse tram line in Aachen opened in December 1880. After electrification in 1895, it attained a maximum length of in 1915, thus becoming the fourth-longest tram network in Germany. Many tram lines extended to the surrounding towns of Herzogenrath, Stolberg, Alsdorf as well as the Belgian and Dutch communes of Vaals, Kelmis (then "Altenberg") and Eupen. The Aachen tram system was linked with the Belgian national interurban tram system. Like many tram systems in Western Europe, the Aachen tram suffered from poorly-maintained infrastructure and was so deemed unnecessary and disrupting for car drivers by local politics. On 28 September 1974, the last line 15 (Vaals–Brand) operated for one last day and was then replaced by buses. A proposal to reinstate a tram/light rail system under the name "Campusbahn" was dropped after a referendum.


title: Aachen

text: Today, the ASEAG ("Aachener Straßenbahn und Energieversorgungs-AG", literally "Aachen tram and power supply company") operates a bus network with 68 bus routes. Because of the location at the border, many bus routes extend to Belgium and the Netherlands. Lines 14 to Eupen, Belgium and 44 to Heerlen, Netherlands are jointly operated with Transport en Commun and Veolia Transport Nederland, respectively. ASEAG is one of the main participants in the Aachener Verkehrsverbund (AVV), a tariff association in the region. Along with ASEAG, city bus routes of Aachen are served by private contractors such as Sadar, Taeter, Schlömer, or DB Regio Bus. Line 350, which runs from Maastricht, also enters Aachen.


title: Aachen

text: Aachen is connected to the Autobahn A4 (west-east), A44 (north-south) and A544 (a smaller motorway from the A4 to the "Europaplatz" near the city centre). There are plans to eliminate traffic jams at the Aachen road interchange.


title: Aachen

text: Maastricht Aachen Airport is the main airport of Aachen and Maastricht. It is located around 15 nautical miles (28 km; 17 mi) northwest of Aachen. There is a shuttle-service between Aachen and the airport.


title: Aachen

text: Since 1950, a committee of Aachen citizens annually awards the Charlemagne Prize () to personalities of outstanding service to the unification of Europe. It is traditionally awarded on Ascension Day at the City Hall. In 2016, the Charlemagne Award was awarded to Pope Francis.


title: Aachen

text: The International Charlemagne Prize of Aachen was awarded in the year 2000 to US president Bill Clinton, for his special personal contribution to co-operation with the states of Europe, for the preservation of peace, freedom, democracy and human rights in Europe, and for his support of the enlargement of the European Union. In 2004, Pope John Paul II's efforts to unite Europe were honoured with an "Extraordinary Charlemagne Medal", which was awarded for the only time ever.


title: Aachen

text: Aix is the destination in Robert Browning's poem "How They Brought the Good News from Ghent to Aix", which was published in "Dramatic Romances and Lyrics", 1845. The poem is a first-person narrative told, in breathless galloping meter, by one of three riders; an urgent midnight errand to deliver "the news which alone could save Aix from her fate".


title: Optical fiber

text: An optical fiber, or optical fibre in Commonwealth 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 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.


title: Optical fiber

text: 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 .


title: Optical fiber

text: 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.


title: Optical fiber

text: 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.


title: Optical fiber

text: Daniel Colladon and Jacques Babinet first demonstrated the guiding of light by refraction, the principle that makes fiber optics possible, in Paris in the early 1840s. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870:


title: Optical fiber

text: In the late 19th century, a team of Viennese doctors guided light through bent glass rods to illuminate body cavities. Practical applications such as close internal illumination during dentistry followed, early in the twentieth century. Image transmission through tubes was demonstrated independently by the radio experimenter Clarence Hansell and the television pioneer John Logie Baird in the 1920s. In the 1930s, Heinrich Lamm showed that one could transmit images through a bundle of unclad optical fibers and used it for internal medical examinations, but his work was largely forgotten.


title: Optical fiber

text: In 1953, Dutch scientist first demonstrated image transmission through bundles of optical fibers with a transparent cladding. That same year, Harold Hopkins and Narinder Singh Kapany at Imperial College in London succeeded in making image-transmitting bundles with over 10,000 fibers, and subsequently achieved image transmission through a 75 cm long bundle which combined several thousand fibers. The first practical fiber optic semi-flexible gastroscope was patented by Basil Hirschowitz, C. Wilbur Peters, and Lawrence E. Curtiss, researchers at the University of Michigan, in 1956. In the process of developing the gastroscope, Curtiss produced the first glass-clad fibers; previous optical fibers had relied on air or impractical oils and waxes as the low-index cladding material.


title: Optical fiber

text: Kapany coined the term "fiber optics" after writing a 1960 article in "Scientific American" that introduced the topic to a wide audience. He subsequently wrote the first book about the new field.


title: Optical fiber

text: The first working fiber-optic data transmission system was demonstrated by German physicist Manfred Börner at Telefunken Research Labs in Ulm in 1965, followed by the first patent application for this technology in 1966. In 1968, NASA used fiber optics in the television cameras that were sent to the moon. At the time, the use in the cameras was classified "confidential", and employees handling the cameras had to be supervised by someone with an appropriate security clearance.


title: Optical fiber

text: Charles K. Kao and George A. Hockham of the British company Standard Telephones and Cables (STC) were the first to promote the idea that the attenuation in optical fibers could be reduced below 20 decibels per kilometer (dB/km), making fibers a practical communication medium, in 1965. They proposed that the attenuation in fibers available at the time was caused by impurities that could be removed, rather than by fundamental physical effects such as scattering. They correctly and systematically theorized the light-loss properties for optical fiber and pointed out the right material to use for such fibers—silica glass with high purity. This discovery earned Kao the Nobel Prize in Physics in 2009. The crucial attenuation limit of 20 dB/km was first achieved in 1970 by researchers Robert D. Maurer, Donald Keck, Peter C. Schultz, and Frank Zimar working for American glass maker Corning Glass Works. They demonstrated a fiber with 17 dB/km attenuation by doping silica glass with titanium. A few years later they produced a fiber with only 4 dB/km attenuation using germanium dioxide as the core dopant. In 1981, General Electric produced fused quartz ingots that could be drawn into strands long.


title: Optical fiber

text: Initially, high-quality optical fibers could only be manufactured at 2 meters per second. Chemical engineer Thomas Mensah joined Corning in 1983 and increased the speed of manufacture to over 50 meters per second, making optical fiber cables cheaper than traditional copper ones. These innovations ushered in the era of optical fiber telecommunication.


title: Optical fiber

text: The Italian research center CSELT worked with Corning to develop practical optical fiber cables, resulting in the first metropolitan fiber optic cable being deployed in Turin in 1977. CSELT also developed an early technique for splicing optical fibers, called Springroove.


title: Optical fiber

text: Attenuation in modern optical cables is far less than in electrical copper cables, leading to long-haul fiber connections with repeater distances of . Two teams, led by David N. Payne of the University of Southampton and Emmanuel Desurvire at Bell Labs, developed the erbium-doped fiber amplifier, which reduced the cost of long-distance fiber systems by reducing or eliminating optical-electrical-optical repeaters, in 1986 and 1987 respectively.


title: Optical fiber

text: The emerging field of photonic crystals led to the development in 1991 of photonic-crystal fiber, which guides light by diffraction from a periodic structure, rather than by total internal reflection. The first photonic crystal fibers became commercially available in 2000. Photonic crystal fibers can carry higher power than conventional fibers and their wavelength-dependent properties can be manipulated to improve performance.


title: Optical fiber

text: Optical fiber is used as a medium for telecommunication and computer networking because it is flexible and can be bundled as cables. It is especially advantageous for long-distance communications, because infrared light propagates through the fiber with much lower attenuation compared to electricity in electrical cables. This allows long distances to be spanned with few repeaters.


title: Optical fiber

text: Through the use of wavelength-division multiplexing (WDM), each fiber can carry many independent channels, each using a different wavelength of light. The net data rate (data rate without overhead bytes) per fiber is the per-channel data rate reduced by the forward error correction (FEC) overhead, multiplied by the number of channels (usually up to 80 in commercial dense WDM systems ).


title: Optical fiber

text: For short-distance applications, such as a network in an office building (see fiber to the office), fiber-optic cabling can save space in cable ducts. This is because a single fiber can carry much more data than electrical cables such as standard category 5 cable, which typically runs at 100 Mbit/s or 1 Gbit/s speeds.


title: Optical fiber

text: Fibers are often also used for short-distance connections between devices. For example, most high-definition televisions offer a digital audio optical connection. This allows the streaming of audio over light, using the S/PDIF protocol over an optical TOSLINK connection.


title: Optical fiber

text: Fibers have many uses in remote sensing. In some applications, the sensor is itself an optical fiber. Fibers are used to channel radiation to a sensor where it is measured. In other cases, fiber is used to connect a sensor to a measurement system.


title: Optical fiber

text: Optical fibers can be used as sensors to measure strain, temperature, pressure, and other quantities by modifying a fiber so that the property being measured modulates the intensity, phase, polarization, wavelength, or transit time of light in the fiber. Sensors that vary the intensity of light are the simplest since only a simple source and detector are required. A particularly useful feature of such fiber optic sensors is that they can, if required, provide distributed sensing over distances of up to one meter. Distributed acoustic sensing is one example of this.


title: Optical fiber

text: In contrast, highly localized measurements can be provided by integrating miniaturized sensing elements with the tip of the fiber. These can be implemented by various micro- and nanofabrication technologies, such that they do not exceed the microscopic boundary of the fiber tip, allowing for such applications as insertion into blood vessels via hypodermic needle.


title: Optical fiber

text: Extrinsic fiber optic sensors use an optical fiber cable, normally a multi-mode one, to transmit modulated light from either a non-fiber optical sensor—or an electronic sensor connected to an optical transmitter. A major benefit of extrinsic sensors is their ability to reach otherwise inaccessible places. An example is the measurement of temperature inside jet engines by using a fiber to transmit radiation into a pyrometer outside the engine. Extrinsic sensors can be used in the same way to measure the internal temperature of electrical transformers, where the extreme electromagnetic fields present make other measurement techniques impossible. Extrinsic sensors measure vibration, rotation, displacement, velocity, acceleration, torque, and torsion. A solid-state version of the gyroscope, using the interference of light, has been developed. The fiber optic gyroscope (FOG) has no moving parts and exploits the Sagnac effect to detect mechanical rotation.


title: Optical fiber

text: Common uses for fiber optic sensors include advanced intrusion detection security systems. The light is transmitted along a fiber optic sensor cable placed on a fence, pipeline, or communication cabling, and the returned signal is monitored and analyzed for disturbances. This return signal is digitally processed to detect disturbances and trip an alarm if an intrusion has occurred.


title: Optical fiber

text: Optical fiber can be used to transmit power using a photovoltaic cell to convert the light into electricity. While this method of power transmission is not as efficient as conventional ones, it is especially useful in situations where it is desirable not to have a metallic conductor as in the case of use near MRI machines, which produce strong magnetic fields. Other examples are for powering electronics in high-powered antenna elements and measurement devices used in high-voltage transmission equipment.


title: Optical fiber

text: Optical fibers are used as light guides in medical and other applications where bright light needs to be shone on a target without a clear line-of-sight path. Many microscopes use fiber-optic light sources to provide intense illumination of samples being studied.


title: Optical fiber

text: Optical fiber is also used in imaging optics. A coherent bundle of fibers is used, sometimes along with lenses, for a long, thin imaging device called an endoscope, which is used to view objects through a small hole. Medical endoscopes are used for minimally invasive exploratory or surgical procedures. Industrial endoscopes (see fiberscope or borescope) are used for inspecting anything hard to reach, such as jet engine interiors.


title: Optical fiber

text: In some buildings, optical fibers route sunlight from the roof to other parts of the building (see nonimaging optics). Optical-fiber lamps are used for illumination in decorative applications, including signs, art, toys and artificial Christmas trees. Optical fiber is an intrinsic part of the light-transmitting concrete building product LiTraCon.


title: Optical fiber

text: Optical fiber can also be used in structural health monitoring. This type of sensor can detect stresses that may have a lasting impact on structures. It is based on the principle of measuring analog attenuation.


title: Optical fiber

text: In spectroscopy, optical fiber bundles transmit light from a spectrometer to a substance that cannot be placed inside the spectrometer itself, in order to analyze its composition. A spectrometer analyzes substances by bouncing light off and through them. By using fibers, a spectrometer can be used to study objects remotely.


title: Optical fiber

text: An optical fiber doped with certain rare-earth elements such as erbium can be used as the gain medium of a fiber laser or optical amplifier. Rare-earth-doped optical fibers can be used to provide signal amplification by splicing a short section of doped fiber into a regular (undoped) optical fiber line. The doped fiber is optically pumped with a second laser wavelength that is coupled into the line in addition to the signal wave. Both wavelengths of light are transmitted through the doped fiber, which transfers energy from the second pump wavelength to the signal wave. The process that causes the amplification is stimulated emission.


title: Optical fiber

text: Optical fiber is also widely exploited as a nonlinear medium. The glass medium supports a host of nonlinear optical interactions, and the long interaction lengths possible in fiber facilitate a variety of phenomena, which are harnessed for applications and fundamental investigation. Conversely, fiber nonlinearity can have deleterious effects on optical signals, and measures are often required to minimize such unwanted effects.


title: Optical fiber

text: Fiber-optic sights for handguns, rifles, and shotguns use pieces of optical fiber to improve the visibility of markings on the sight.


title: Optical fiber

text: An optical fiber is a cylindrical dielectric waveguide (nonconducting waveguide) that transmits light along its axis through the process of total internal reflection. The fiber consists of a "core" surrounded by a cladding layer, both of which are made of dielectric materials. To confine the optical signal in the core, the refractive index of the core must be greater than that of the cladding. The boundary between the core and cladding may either be abrupt, in "step-index fiber", or gradual, in "graded-index fiber". Light can be fed into optical fibers using lasers or LEDs.


title: Optical fiber

text: Fiber is immune to electrical interference; there is no cross-talk between signals in different cables and no pickup of environmental noise. Information traveling inside the optical fiber is even immune to electromagnetic pulses generated by nuclear devices.


title: Optical fiber

text: Fiber cables do not conduct electricity, which makes fiber useful for protecting communications equipment in high voltage environments such as power generation facilities or applications prone to lightning strikes. The electrical isolation also prevents problems with ground loops. Because there is no electricity in optical cables that could potentially generate sparks, they can be used in environments where explosive fumes are present. Wiretapping (in this case, fiber tapping) is more difficult compared to electrical connections.


title: Optical fiber

text: Fiber cables are not targeted for metal theft. In contrast, copper cable systems use large amounts of copper and have been targeted since the 2000s commodities boom.


title: Optical fiber

text: The refractive index is a way of measuring the speed of light in a material. Light travels fastest in a vacuum, such as in outer space. The speed of light in a vacuum is about 300,000 kilometers (186,000 miles) per second. The refractive index of a medium is calculated by dividing the speed of light in a vacuum by the speed of light in that medium. The refractive index of a vacuum is therefore 1, by definition. A typical single-mode fiber used for telecommunications has a cladding made of pure silica, with an index of 1.444 at 1500 nm, and a core of doped silica with an index around 1.4475. The larger the index of refraction, the slower light travels in that medium. From this information, a simple rule of thumb is that a signal using optical fiber for communication will travel at around 200,000 kilometers per second. Thus a phone call carried by fiber between Sydney and New York, a 16,000-kilometer distance, means that there is a minimum delay of 80 milliseconds (about formula_1 of a second) between when one caller speaks and the other hears.


title: Optical fiber

text: When light traveling in an optically dense medium hits a boundary at a steep angle (larger than the critical angle for the boundary), the light is completely reflected. This is called total internal reflection. This effect is used in optical fibers to confine light in the core. Most modern optical fiber is "weakly guiding", meaning that the difference in refractive index between the core and the cladding is very small (typically less than 1%). Light travels through the fiber core, bouncing back and forth off the boundary between the core and cladding.


title: Optical fiber

text: Because the light must strike the boundary with an angle greater than the critical angle, only light that enters the fiber within a certain range of angles can travel down the fiber without leaking out. This range of angles is called the acceptance cone of the fiber. There is a maximum angle from the fiber axis at which light may enter the fiber so that it will propagate, or travel, in the core of the fiber. The sine of this maximum angle is the numerical aperture (NA) of the fiber. Fiber with a larger NA requires less precision to splice and work with than fiber with a smaller NA. The size of this acceptance cone is a function of the refractive index difference between the fiber's core and cladding. Single-mode fiber has a small NA.


title: Optical fiber

text: Fiber with large core diameter (greater than 10 micrometers) may be analyzed by geometrical optics. Such fiber is called "multi-mode fiber", from the electromagnetic analysis (see below). In a step-index multi-mode fiber, rays of light are guided along the fiber core by total internal reflection. Rays that meet the core-cladding boundary at an angle (measured relative to a line normal to the boundary) greater than the critical angle for this boundary, are completely reflected. The critical angle is determined by the difference in the index of refraction between the core and cladding materials. Rays that meet the boundary at a low angle are refracted from the core into the cladding where they terminate. The critical angle determines the acceptance angle of the fiber, often reported as a numerical aperture. A high numerical aperture allows light to propagate down the fiber in rays both close to the axis and at various angles, allowing efficient coupling of light into the fiber. However, this high numerical aperture increases the amount of dispersion as rays at different angles have different path lengths and therefore take different amounts of time to traverse the fiber.


title: Optical fiber

text: In graded-index fiber, the index of refraction in the core decreases continuously between the axis and the cladding. This causes light rays to bend smoothly as they approach the cladding, rather than reflecting abruptly from the core-cladding boundary. The resulting curved paths reduce multi-path dispersion because high-angle rays pass more through the lower-index periphery of the core, rather than the high-index center. The index profile is chosen to minimize the difference in axial propagation speeds of the various rays in the fiber. This ideal index profile is very close to a parabolic relationship between the index and the distance from the axis.


title: Optical fiber

text: Fiber with a core diameter less than about ten times the wavelength of the propagating light cannot be modeled using geometric optics. Instead, it must be analyzed as an electromagnetic waveguide structure, according to Maxwell's equations as reduced to the electromagnetic wave equation. As an optical waveguide, the fiber supports one or more confined transverse modes by which light can propagate along the fiber. Fiber supporting only one mode is called "single-mode". The waveguide analysis shows that the light energy in the fiber is not completely confined in the core. Instead, especially in single-mode fibers, a significant fraction of the energy in the bound mode travels in the cladding as an evanescent wave. The most common type of single-mode fiber has a core diameter of 8–10 micrometers and is designed for use in the near infrared. Multi-mode fiber, by comparison, is manufactured with core diameters as small as 50 micrometers and as large as hundreds of micrometers.


title: Optical fiber

text: Some special-purpose optical fiber is constructed with a non-cylindrical core or cladding layer, usually with an elliptical or rectangular cross-section. These include polarization-maintaining fiber used in fiber optic sensors and fiber designed to suppress whispering gallery mode propagation.


title: Optical fiber

text: Photonic-crystal fiber is made with a regular pattern of index variation (often in the form of cylindrical holes that run along the length of the fiber). Such fiber uses diffraction effects instead of or in addition to total internal reflection, to confine light to the fiber's core. The properties of the fiber can be tailored to a wide variety of applications.


title: Optical fiber

text: Attenuation in fiber optics, also known as transmission loss, is the reduction in the intensity of the light signal as it travels through the transmission medium. Attenuation coefficients in fiber optics are usually expressed in units of dB/km. The medium is usually a fiber of silica glass that confines the incident light beam within. Attenuation is an important factor limiting the transmission of a digital signal across large distances. Thus, much research has gone into both limiting the attenuation and maximizing the amplification of the optical signal. The four orders of magnitude reduction in the attenuation of silica optical fibers over four decades was the result of constant improvement of manufacturing processes, raw material purity, preform, and fiber designs, which allowed for these fibers to approach the theoretical lower limit of attenuation.


title: Optical fiber

text: Single-mode optical fibers can be made with extremely low loss. Corning's SMF-28 fiber, a standard single-mode fiber for telecommunications wavelengths, has a loss of 0.17 dB/km at 1550 nm. For example, an 8 km length of SMF-28 transmits nearly 75% of light at 1,550 nm. It has been noted that if ocean water was as clear as fiber, one could see all the way to the bottom even of the Mariana Trench in the Pacific Ocean, a depth of .


title: Optical fiber

text: Empirical research has shown that attenuation in optical fiber is caused primarily by both scattering and absorption.


title: Optical fiber

text: The propagation of light through the core of an optical fiber is based on the total internal reflection of the lightwave. Rough and irregular surfaces, even at the molecular level, can cause light rays to be reflected in random directions. This is called diffuse reflection or scattering, and it is typically characterized by a wide variety of reflection angles.


title: Optical fiber

text: Scattering depends on the wavelength of the light being scattered. Thus, limits to spatial scales of visibility arise, depending on the frequency of the incident light wave and the physical dimension (or spatial scale) of the scattering center, which is typically in the form of some specific micro-structural feature. Since visible light has a wavelength of the order of one micrometer (one-millionth of a meter) scattering centers will have dimensions on a similar spatial scale.


title: Optical fiber

text: Thus, attenuation results from the incoherent scattering of light at internal surfaces and interfaces. In (poly)crystalline materials such as metals and ceramics, in addition to pores, most of the internal surfaces or interfaces are in the form of grain boundaries that separate tiny regions of crystalline order. It has been shown that when the size of the scattering center (or grain boundary) is reduced below the size of the wavelength of the light being scattered, the scattering no longer occurs to any significant extent. This phenomenon has given rise to the production of transparent ceramic materials.


title: Optical fiber

text: Similarly, the scattering of light in optical quality glass fiber is caused by molecular level irregularities (compositional fluctuations) in the glass structure. Indeed, one emerging school of thought is that glass is simply the limiting case of a polycrystalline solid. Within this framework, "domains" exhibiting various degrees of short-range order become the building blocks of metals as well as glasses and ceramics. Distributed both between and within these domains are micro-structural defects that provide the most ideal locations for light scattering. This same phenomenon is seen as one of the limiting factors in the transparency of IR missile domes.


title: Optical fiber

text: In addition to light scattering, attenuation or signal loss can also occur due to selective absorption of specific wavelengths. Primary material considerations include both electrons and molecules as follows:


title: Optical fiber

text: The design of any optically transparent device requires the selection of materials based upon knowledge of its properties and limitations. The crystal structure absorption characteristics observed at the lower frequency regions (mid- to far-IR wavelength range) define the long-wavelength transparency limit of the material. They are the result of the interactive coupling between the motions of thermally induced vibrations of the constituent atoms and molecules of the solid lattice and the incident light wave radiation. Hence, all materials are bounded by limiting regions of absorption caused by atomic and molecular vibrations (bond-stretching) in the far-infrared (>10 µm).


title: Optical fiber

text: In other words, the selective absorption of IR light by a particular material occurs because the selected frequency of the light wave matches the frequency (or an integer multiple of the frequency, i.e. harmonic) at which the particles of that material vibrate. Since different atoms and molecules have different natural frequencies of vibration, they will selectively absorb different frequencies (or portions of the spectrum) of IR light.


title: Optical fiber

text: Reflection and transmission of light waves occur because the frequencies of the light waves do not match the natural resonant frequencies of vibration of the objects. When IR light of these frequencies strikes an object, the energy is either reflected or transmitted.


title: Optical fiber

text: Attenuation over a cable run is significantly increased by the inclusion of connectors and splices. When computing the acceptable attenuation (loss budget) between a transmitter and a receiver one includes:


title: Optical fiber

text: Connectors typically introduce 0.3 dB per connector on well-polished connectors. Splices typically introduce less than 0.2 dB per splice.


title: Optical fiber

text: where the dB loss per kilometer is a function of the type of fiber and can be found in the manufacturer's specifications. For example, a typical 1550 nm single-mode fiber has a loss of 0.3 dB per kilometer.


title: Optical fiber

text: The calculated loss budget is used when testing to confirm that the measured loss is within the normal operating parameters.


title: Optical fiber

text: Glass optical fibers are almost always made from silica, but some other materials, such as fluorozirconate, fluoroaluminate, and chalcogenide glasses as well as crystalline materials like sapphire, are used for longer-wavelength infrared or other specialized applications. Silica and fluoride glasses usually have refractive indices of about 1.5, but some materials such as the chalcogenides can have indices as high as 3. Typically the index difference between core and cladding is less than one percent.


title: Optical fiber

text: Plastic optical fibers (POF) are commonly step-index multi-mode fibers with a core diameter of 0.5 millimeters or larger. POF typically have higher attenuation coefficients than glass fibers, 1 dB/m or higher, and this high attenuation limits the range of POF-based systems.


title: Optical fiber

text: Silica exhibits fairly good optical transmission over a wide range of wavelengths. In the near-infrared (near IR) portion of the spectrum, particularly around 1.5 μm, silica can have extremely low absorption and scattering losses of the order of 0.2 dB/km. Such low losses depend on using ultra-pure silica. A high transparency in the 1.4-μm region is achieved by maintaining a low concentration of hydroxyl groups (OH). Alternatively, a high OH concentration is better for transmission in the ultraviolet (UV) region.


title: Optical fiber

text: Silica can be drawn into fibers at reasonably high temperatures and has a fairly broad glass transformation range. One other advantage is that fusion splicing and cleaving of silica fibers is relatively effective. Silica fiber also has high mechanical strength against both pulling and even bending, provided that the fiber is not too thick and that the surfaces have been well prepared during processing. Even simple cleaving of the ends of the fiber can provide nicely flat surfaces with acceptable optical quality. Silica is also relatively chemically inert. In particular, it is not hygroscopic (does not absorb water).


title: Optical fiber

text: Silica glass can be doped with various materials. One purpose of doping is to raise the refractive index (e.g. with germanium dioxide (GeO) or aluminium oxide (AlO)) or to lower it (e.g. with fluorine or boron trioxide (BO)). Doping is also possible with laser-active ions (for example, rare-earth-doped fibers) in order to obtain active fibers to be used, for example, in fiber amplifiers or laser applications. Both the fiber core and cladding are typically doped, so that the entire assembly (core and cladding) is effectively the same compound (e.g. an aluminosilicate, germanosilicate, phosphosilicate or borosilicate glass).


title: Optical fiber

text: Particularly for active fibers, pure silica is usually not a very suitable host glass, because it exhibits a low solubility for rare-earth ions. This can lead to quenching effects due to the clustering of dopant ions. Aluminosilicates are much more effective in this respect.


title: Optical fiber

text: Silica fiber also exhibits a high threshold for optical damage. This property ensures a low tendency for laser-induced breakdown. This is important for fiber amplifiers when utilized for the amplification of short pulses.


title: Optical fiber

text: Because of these properties, silica fibers are the material of choice in many optical applications, such as communications (except for very short distances with plastic optical fiber), fiber lasers, fiber amplifiers, and fiber-optic sensors. Large efforts put forth in the development of various types of silica fibers have further increased the performance of such fibers over other materials.


title: Optical fiber

text: Fluoride glass is a class of non-oxide optical quality glasses composed of fluorides of various metals. Because of their low viscosity, it is very difficult to completely avoid crystallization while processing it through the glass transition (or drawing the fiber from the melt). Thus, although heavy metal fluoride glasses (HMFG) exhibit very low optical attenuation, they are not only difficult to manufacture, but are quite fragile, and have poor resistance to moisture and other environmental attacks. Their best attribute is that they lack the absorption band associated with the hydroxyl (OH) group (3,200–3,600 cm; i.e., 2,777–3,125 nm or 2.78–3.13 μm), which is present in nearly all oxide-based glasses.


title: Optical fiber

text: An example of a heavy metal fluoride glass is the ZBLAN glass group, composed of zirconium, barium, lanthanum, aluminium, and sodium fluorides. Their main technological application is as optical waveguides in both planar and fiber form. They are advantageous especially in the mid-infrared (2,000–5,000 nm) range.


title: Optical fiber

text: HMFGs were initially slated for optical fiber applications, because the intrinsic losses of a mid-IR fiber could in principle be lower than those of silica fibers, which are transparent only up to about 2 μm. However, such low losses were never realized in practice, and the fragility and high cost of fluoride fibers made them less than ideal as primary candidates. Later, the utility of fluoride fibers for various other applications was discovered. These include mid-IR spectroscopy, fiber optic sensors, thermometry, and imaging. Also, fluoride fibers can be used for guided lightwave transmission in media such as YAG (yttrium aluminium garnet) lasers at 2.9 μm, as required for medical applications (e.g. ophthalmology and dentistry).


title: Optical fiber

text: Phosphate glass constitutes a class of optical glasses composed of metaphosphates of various metals. Instead of the SiO tetrahedra observed in silicate glasses, the building block for this glass former is phosphorus pentoxide (PO), which crystallizes in at least four different forms. The most familiar polymorph (see figure) comprises molecules of PO.


title: Optical fiber

text: Phosphate glasses can be advantageous over silica glasses for optical fibers with a high concentration of doping rare-earth ions. A mix of fluoride glass and phosphate glass is fluorophosphate glass.


title: Optical fiber

text: The chalcogens—the elements in group 16 of the periodic table—particularly sulfur (S), selenium (Se) and tellurium (Te)—react with more electropositive elements, such as silver, to form chalcogenides. These are extremely versatile compounds, in that they can be crystalline or amorphous, metallic or semiconducting, and conductors of ions or electrons. Glass containing chalcogenides can be used to make fibers for far infrared transmission.


title: Optical fiber

text: Standard optical fibers are made by first constructing a large-diameter "preform" with a carefully controlled refractive index profile, and then "pulling" the preform to form the long, thin optical fiber. The preform is commonly made by three chemical vapor deposition methods: "inside vapor deposition", "outside vapor deposition", and "vapor axial deposition".


title: Optical fiber

text: With "inside vapor deposition", the preform starts as a hollow glass tube approximately long, which is placed horizontally and rotated slowly on a lathe. Gases such as silicon tetrachloride (SiCl) or germanium tetrachloride (GeCl) are injected with oxygen in the end of the tube. The gases are then heated by means of an external hydrogen burner, bringing the temperature of the gas up to 1,900 K (1,600 °C, 3,000 °F), where the tetrachlorides react with oxygen to produce silica or germania (germanium dioxide) particles. When the reaction conditions are chosen to allow this reaction to occur in the gas phase throughout the tube volume, in contrast to earlier techniques where the reaction occurred only on the glass surface, this technique is called "modified chemical vapor deposition (MCVD)".


title: Optical fiber

text: The oxide particles then agglomerate to form large particle chains, which subsequently deposit on the walls of the tube as soot. The deposition is due to the large difference in temperature between the gas core and the wall causing the gas to push the particles outward (this is known as thermophoresis). The torch is then traversed up and down the length of the tube to deposit the material evenly. After the torch has reached the end of the tube, it is then brought back to the beginning of the tube and the deposited particles are then melted to form a solid layer. This process is repeated until a sufficient amount of material has been deposited. For each layer the composition can be modified by varying the gas composition, resulting in precise control of the finished fiber's optical properties.


title: Optical fiber

text: In outside vapor deposition or vapor axial deposition, the glass is formed by "flame hydrolysis", a reaction in which silicon tetrachloride and germanium tetrachloride are oxidized by reaction with water (HO) in an oxyhydrogen flame. In outside vapor deposition, the glass is deposited onto a solid rod, which is removed before further processing. In vapor axial deposition, a short "seed rod" is used, and a porous preform, whose length is not limited by the size of the source rod, is built up on its end. The porous preform is consolidated into a transparent, solid preform by heating to about 1,800 K (1,500 °C, 2,800 °F).


title: Optical fiber

text: Typical communications fiber uses a circular preform. For some applications such as double-clad fibers another form is preferred. In fiber lasers based on double-clad fiber, an asymmetric shape improves the filling factor for laser pumping.


title: Optical fiber

text: Because of the surface tension, the shape is smoothed during the drawing process, and the shape of the resulting fiber does not reproduce the sharp edges of the preform. Nevertheless, careful polishing of the preform is important, since any defects of the preform surface affect the optical and mechanical properties of the resulting fiber. In particular, the preform for the test fiber shown in the figure was not polished well, and cracks are seen with the confocal optical microscope.


title: Optical fiber

text: The preform, regardless of construction, is placed in a device known as a drawing tower, where the preform tip is heated and the optical fiber is pulled out as a string. By measuring the resultant fiber width, the tension on the fiber can be controlled to maintain the fiber thickness.


title: Optical fiber

text: The light is guided down the core of the fiber by an optical cladding with a lower refractive index that traps light in the core through total internal reflection.


title: Optical fiber

text: The cladding is coated by a buffer that protects it from moisture and physical damage. The buffer coating is what gets stripped off the fiber for termination or splicing. These coatings are UV-cured urethane acrylate composite or polyimide materials applied to the outside of the fiber during the drawing process. The coatings protect the very delicate strands of glass fiber—about the size of a human hair—and allow it to survive the rigors of manufacturing, proof testing, cabling, and installation.


title: Optical fiber

text: Today’s glass optical fiber draw processes employ a dual-layer coating approach. An inner primary coating is designed to act as a shock absorber to minimize attenuation caused by microbending. An outer secondary coating protects the primary coating against mechanical damage and acts as a barrier to lateral forces, and may be colored to differentiate strands in bundled cable constructions.


title: Optical fiber

text: These fiber optic coating layers are applied during the fiber draw, at speeds approaching . Fiber optic coatings are applied using one of two methods: "wet-on-dry" and "wet-on-wet". In wet-on-dry, the fiber passes through a primary coating application, which is then UV cured—then through the secondary coating application, which is subsequently cured. In wet-on-wet, the fiber passes through both the primary and secondary coating applications, then goes to UV curing.


title: Optical fiber

text: Fiber optic coatings are applied in concentric layers to prevent damage to the fiber during the drawing application and to maximize fiber strength and microbend resistance. Unevenly coated fiber will experience non-uniform forces when the coating expands or contracts and is susceptible to greater signal attenuation. Under proper drawing and coating processes, the coatings are concentric around the fiber, continuous over the length of the application, and have a constant thickness.


title: Optical fiber

text: The thickness of the coating is taken into account when calculating the stress that the fiber experiences under different bend configurations. When a coated fiber is wrapped around a mandrel, the stress experienced by the fiber is given by


title: Optical fiber

text: where is the fiber’s Young’s modulus, is the diameter of the mandrel, is the diameter of the cladding and is the diameter of the coating.


title: Optical fiber

text: In a two-point bend configuration, a coated fiber is bent in a U-shape and placed between the grooves of two faceplates, which are brought together until the fiber breaks. The stress in the fiber in this configuration is given by


title: Optical fiber

text: where is the distance between the faceplates. The coefficient 1.198 is a geometric constant associated with this configuration.


title: Optical fiber

text: Fiber optic coatings protect the glass fibers from scratches that could lead to strength degradation. The combination of moisture and scratches accelerates the aging and deterioration of fiber strength. When fiber is subjected to low stresses over a long period, fiber fatigue can occur. Over time or in extreme conditions, these factors combine to cause microscopic flaws in the glass fiber to propagate, which can ultimately result in fiber failure.


title: Optical fiber

text: Three key characteristics of fiber optic waveguides can be affected by environmental conditions: strength, attenuation, and resistance to losses caused by microbending. External optical fiber cable jackets and buffer tubes protect glass optical fiber from environmental conditions that can affect the fiber’s performance and long-term durability. On the inside, coatings ensure the reliability of the signal being carried and help minimize attenuation due to microbending.


title: Optical fiber

text: In practical fibers, the cladding is usually coated with a tough resin coating and an additional "buffer" layer, which may be further surrounded by a "jacket" layer, usually plastic. These layers add strength to the fiber but do not contribute to its optical wave guide properties. Rigid fiber assemblies sometimes put light-absorbing ("dark") glass between the fibers, to prevent light that leaks out of one fiber from entering another. This reduces crosstalk between the fibers, or reduces flare in fiber bundle imaging applications.


title: Optical fiber

text: Modern cables come in a wide variety of sheathings and armor, designed for applications such as direct burial in trenches, high voltage isolation, dual use as power lines, installation in conduit, lashing to aerial telephone poles, submarine installation, and insertion in paved streets. Multi-fiber cable usually uses colored coatings and/or buffers to identify each strand. The cost of small fiber-count pole-mounted cables has greatly decreased due to the high demand for fiber to the home (FTTH) installations in Japan and South Korea.


title: Optical fiber

text: Some fiber optic cable versions are reinforced with aramid yarns or glass yarns as an intermediary strength member. In commercial terms, usage of the glass yarns are more cost-effective while no loss in mechanical durability of the cable. Glass yarns also protect the cable core against rodents and termites.


title: Optical fiber

text: Fiber cable can be very flexible, but traditional fiber's loss increases greatly if the fiber is bent with a radius smaller than around 30 mm. This creates a problem when the cable is bent around corners or wound around a spool, making FTTX installations more complicated. "Bendable fibers", targeted toward easier installation in home environments, have been standardized as ITU-T G.657. This type of fiber can be bent with a radius as low as 7.5 mm without adverse impact. Even more bendable fibers have been developed. Bendable fiber may also be resistant to fiber hacking, in which the signal in a fiber is surreptitiously monitored by bending the fiber and detecting the leakage.


title: Optical fiber

text: Another important feature of cable is cable's ability to withstand horizontally applied force. It is technically called max tensile strength defining how much force can be applied to the cable during the installation period.


title: Optical fiber

text: Optical fibers are connected to terminal equipment by optical fiber connectors. These connectors are usually of a standard type such as "FC", "SC", "ST", "LC", "MTRJ", "MPO" or "SMA". Optical fibers may be connected by connectors, or permanently by "splicing", that is, joining two fibers together to form a continuous optical waveguide. The generally accepted splicing method is arc fusion splicing, which melts the fiber ends together with an electric arc. For quicker fastening jobs, a “mechanical splice” is used.


title: Optical fiber

text: Fusion splicing is done with a specialized instrument. The fiber ends are first stripped of their protective polymer coating (as well as the more sturdy outer jacket, if present). The ends are "cleaved" (cut) with a precision cleaver to make them perpendicular, and are placed into special holders in the fusion splicer. The splice is usually inspected via a magnified viewing screen to check the cleaves before and after the splice. The splicer uses small motors to align the end faces together, and emits a small spark between electrodes at the gap to burn off dust and moisture. Then the splicer generates a larger spark that raises the temperature above the melting point of the glass, fusing the ends permanently. The location and energy of the spark is carefully controlled so that the molten core and cladding do not mix, and this minimizes optical loss. A splice loss estimate is measured by the splicer, by directing light through the cladding on one side and measuring the light leaking from the cladding on the other side. A splice loss under 0.1 dB is typical. The complexity of this process makes fiber splicing much more difficult than splicing copper wire.


title: Optical fiber

text: Mechanical fiber splices are designed to be quicker and easier to install, but there is still the need for stripping, careful cleaning, and precision cleaving. The fiber ends are aligned and held together by a precision-made sleeve, often using a clear index-matching gel that enhances the transmission of light across the joint. Such joints typically have a higher optical loss and are less robust than fusion splices, especially if the gel is used. All splicing techniques involve installing an enclosure that protects the splice.


title: Optical fiber

text: Fibers are terminated in connectors that hold the fiber end precisely and securely. A fiber-optic connector is a rigid cylindrical barrel surrounded by a sleeve that holds the barrel in its mating socket. The mating mechanism can be "push and click", "turn and latch" ("bayonet mount"), or "screw-in" ("threaded"). The barrel is typically free to move within the sleeve and may have a key that prevents the barrel and fiber from rotating as the connectors are mated.


title: Optical fiber

text: A typical connector is installed by preparing the fiber end and inserting it into the rear of the connector body. Quick-set adhesive is usually used to hold the fiber securely, and a strain relief is secured to the rear. Once the adhesive sets, the fiber's end is polished to a mirror finish. Various polish profiles are used, depending on the type of fiber and the application. For single-mode fiber, fiber ends are typically polished with a slight curvature that makes the mated connectors touch only at their cores. This is called a "physical contact" (PC) polish. The curved surface may be polished at an angle, to make an "angled physical contact (APC)" connection. Such connections have higher loss than PC connections but greatly reduced back reflection, because light that reflects from the angled surface leaks out of the fiber core. The resulting signal strength loss is called "gap loss". APC fiber ends have low back reflection even when disconnected.


title: Optical fiber

text: In the 1990s, terminating fiber optic cables was labor-intensive. The number of parts per connector, polishing of the fibers, and the need to oven-bake the epoxy in each connector made terminating fiber optic cables difficult. Today, many connector types are on the market that offer easier, less labor-intensive ways of terminating cables. Some of the most popular connectors are pre-polished at the factory and include a gel inside the connector. Those two steps help save money on labor, especially on large projects. A cleave is made at a required length, to get as close to the polished piece already inside the connector. The gel surrounds the point where the two pieces meet inside the connector for very little light loss. Long-term performance of the gel is a design consideration, so for the most demanding installations, factory pre-polished pigtails of sufficient length to reach the first fusion splice enclosure is normally the safest approach that minimizes on-site labor.


title: Optical fiber

text: It is often necessary to align an optical fiber with another optical fiber or with an optoelectronic device such as a light-emitting diode, a laser diode, or a modulator. This can involve either carefully aligning the fiber and placing it in contact with the device, or can use a lens to allow coupling over an air gap. Typically the size of the fiber mode is much larger than the size of the mode in a laser diode or a silicon optical chip. In this case, a tapered or lensed fiber is used to match the fiber mode field distribution to that of the other element. The lens on the end of the fiber can be formed using polishing, laser cutting or fusion splicing.


title: Optical fiber

text: In a laboratory environment, a bare fiber end is coupled using a fiber launch system, which uses a microscope objective lens to focus the light down to a fine point. A precision translation stage (micro-positioning table) is used to move the lens, fiber, or device to allow the coupling efficiency to be optimized. Fibers with a connector on the end make this process much simpler: the connector is simply plugged into a pre-aligned fiber-optic collimator, which contains a lens that is either accurately positioned to the fiber or is adjustable. To achieve the best injection efficiency into a single-mode fiber, the direction, position, size, and divergence of the beam must all be optimized. With good beams, 70 to 90% coupling efficiency can be achieved.


title: Optical fiber

text: With properly polished single-mode fibers, the emitted beam has an almost perfect Gaussian shape—even in the far field—if a good lens is used. The lens needs to be large enough to support the full numerical aperture of the fiber, and must not introduce aberrations in the beam. Aspheric lenses are typically used.


title: Optical fiber

text: At high optical intensities, above 2 megawatts per square centimeter, when a fiber is subjected to a shock or is otherwise suddenly damaged, a "fiber fuse" can occur. The reflection from the damage vaporizes the fiber immediately before the break, and this new defect remains reflective so that the damage propagates back toward the transmitter at 1–3 meters per second (4–11 km/h, 2–8 mph). The open fiber control system, which ensures laser eye safety in the event of a broken fiber, can also effectively halt propagation of the fiber fuse. In situations, such as undersea cables, where high power levels might be used without the need for open fiber control, a "fiber fuse" protection device at the transmitter can break the circuit to keep damage to a minimum.


title: Optical fiber

text: The refractive index of fibers varies slightly with the frequency of light, and light sources are not perfectly monochromatic. Modulation of the light source to transmit a signal also slightly widens the frequency band of the transmitted light. This has the effect that, over long distances and at high modulation speeds, the different frequencies of light can take different times to arrive at the receiver, ultimately making the signal impossible to discern, and requiring extra repeaters. This problem can be overcome in several ways, including the use of a relatively short length of fiber that has the opposite refractive index gradient.


title: Organisation of Islamic Cooperation

text: The Organisation of Islamic Cooperation (OIC; ; ), formerly the Organisation of the Islamic Conference, is an intergovernmental organization founded in 1969, consisting of 57 member states, with 48 being Muslim-majority countries. The organisation states that it is "the collective voice of the Muslim world" and works to "safeguard and protect the interests of the Muslim world in the spirit of promoting international peace and harmony".


title: Organisation of Islamic Cooperation

text: The OIC has permanent delegations to the United Nations and the European Union. The official languages of the OIC are Arabic, English, and French. It maintains various affiliated, specialized, and subsidiary organs within the framework of OIC Charter. The member states had a collective population of over 1.8 billion as of 2015, accounting for just under a quarter of the world's population. The collective area is 31.66 m km.


title: Organisation of Islamic Cooperation

text: On 21 August 1969, a fire was started in the Al-Aqsa Mosque in Jerusalem. Amin al-Husseini, the former Mufti of Jerusalem, called the arson a "Jewish crime" and called for all Muslim heads of state to convene a summit. The fire, which "destroyed part of the old wooden roof and a 800-year-old pulpit" was blamed on the mental illness of the perpetrator—Australian Christian fundamentalist Denis Michael Rohan—by Israel, and on Zionists and Zionism in general by the Islamic conference.


title: Organisation of Islamic Cooperation

text: On 25 September 1969, an Islamic Conference, a summit of representatives of 24 Muslim majority countries (most of the representatives being heads of state), was held in Rabat, Morocco. A resolution was passed stating that


title: Organisation of Islamic Cooperation

text: Muslim governments would consult with a view to promoting among themselves close cooperation and mutual assistance in the economic, scientific, cultural and spiritual fields, inspired by the immortal teachings of Islam.


title: Organisation of Islamic Cooperation

text: Six months later in March 1970, the First Islamic Conference of Foreign Ministers was held in Jeddah, Saudi Arabia.


title: Organisation of Islamic Cooperation

text: In 1972, the Organisation of the Islamic Conference (OIC, now the Organisation of Islamic Cooperation) was founded.


title: Organisation of Islamic Cooperation

text: While the al-Aqsa fire is regarded as one of the catalysts for the formation of the OIC, many Muslims have aspired to a pan-Islamic institution that would serve the common political, economic, and social interests of the "ummah" (Muslim community) since the 19th century. In particular, the collapse of the Ottoman Empire and the Caliphate after World War I left a vacuum.


title: Organisation of Islamic Cooperation

text: According to its charter, the OIC aims to preserve Islamic social and economic values; promote solidarity amongst member states; increase cooperation in social, economic, cultural, scientific, and political areas; uphold international peace and security; and advance education, particularly in the fields of science and technology.


title: Organisation of Islamic Cooperation

text: The emblem of the OIC contains three main elements that reflect its vision and mission as incorporated in its new Charter. These elements are: the Kaaba, the Globe, and the Crescent.


title: Organisation of Islamic Cooperation

text: On 5 August 1990, 45 foreign ministers of the OIC adopted the Cairo Declaration on Human Rights in Islam to serve as a guidance for the member states in the matters of human rights in as much as they are compatible with the Sharia, or Quranic Law.


title: Organisation of Islamic Cooperation

text: In March 2008, the OIC conducted a formal revision of its charter. The revised charter set out to promote human rights, fundamental freedoms, and good governance in all member states. The revisions also removed any mention of the Cairo Declaration on Human Rights in Islam. Within the revised charter, the OIC has chosen to support the Charter of the United Nations and international law, without mentioning the Universal Declaration of Human Rights.


title: Organisation of Islamic Cooperation

text: On 28 June 2011 during the 38th Council of Foreign Ministers meeting (CFM) in Astana, Kazakhstan, the organisation changed its name from Organisation of the Islamic Conference (; ) to its current name. The OIC also changed its logo at this time.


title: Organisation of Islamic Cooperation

text: In December 2020 a coalition of American Muslim groups criticized the Organization of Islamic Cooperation for failing to speak up to prevent the abuse of the Uyghurs and accused member states of being influenced by Chinese power. The groups included the Council on American-Islamic Relations.


title: Organisation of Islamic Cooperation

text: According to the UNHCR, OIC countries hosted 18 million refugees by the end of 2010. Since then OIC members have absorbed refugees from other conflicts, including the uprising in Syria. In May 2012, the OIC addressed these concerns at the "Refugees in the Muslim World" conference in Ashgabat, Turkmenistan.


title: Organisation of Islamic Cooperation

text: The Organisation of Islamic Cooperation has 57 members, 56 of which are also member states of the United Nations, the exception being Palestine. Some members, especially in West Africa and South America, are—though with large Muslim populations—not necessarily Muslim majority countries. A few countries with significant Muslim populations, such as Russia and Thailand, sit as Observer States.


title: Organisation of Islamic Cooperation

text: The Parliamentary Union of the OIC Member States (PUOICM) was established in Iran in 1999, and its head office is situated in Tehran. Only OIC members are entitled to membership in the union.


title: Organisation of Islamic Cooperation

text: On 27 June 2007, then-United States President George W. Bush announced that the United States would establish an envoy to the OIC. Bush said of the envoy, "Our special envoy will listen to and learn from representatives from Muslim states, and will share with them America's views and values." , Arsalan Suleman is acting special envoy. He was appointed on 13 February 2015. In an investigation of the accuracy of a series of chain emails, Snopes.com reported that during the October 2003April 2004 session of the General Assembly, 17 individual members of the OIC voted against the United States 88% of the time.


title: Organisation of Islamic Cooperation

text: The OIC, on 28 March 2008, joined the criticism of the film "Fitna" by Dutch lawmaker Geert Wilders, which features disturbing images of violent acts juxtaposed with alleged verses from the Quran.


title: Organisation of Islamic Cooperation

text: In March 2015, the OIC announced its support for the Saudi Arabian-led intervention in Yemen against the Shia Houthis.


title: Organisation of Islamic Cooperation

text: The OIC has called for boycott of Israeli products in effort to pressure Israel into ending the occupation of the Palestinian territories.


title: Organisation of Islamic Cooperation

text: There was a meeting in Conakry, Guinea, in 2013. Secretary-General Ekmeleddin Ihsanoglu said that foreign ministers would discuss the possibility of cutting ties with any state that recognised Jerusalem as the capital of Israel or that moves its embassy to its environs.


title: Organisation of Islamic Cooperation

text: In December 2017, the extraordinary meeting held to response Donald Trump's decision on recognizing Jerusalem, resulting "Istanbul Declaration on Freedom for Al Quds."


title: Organisation of Islamic Cooperation

text: In September 2019, the OIC condemned Benjamin Netanyahu's plans to annex the eastern portion of the occupied West Bank known as the Jordan Valley.


title: Organisation of Islamic Cooperation

text: Islam is the second-largest religion in India after Hinduism, with over 200 million Muslims making up approximately 15% of the country's total population; India has the largest Muslim population outside of Muslim-majority or Islamic states. However, India's relationship with Pakistan, the latter being an Islamic state, has been riddled with hostilities and armed conflict since the 1947 Partition of India. The poor relationship between the two states has had a direct impact on India–OIC relations due to Pakistan's status as a founding member of the organization. India has pushed for the OIC to accept it as a member state, arguing that Indian Muslims comprise 11% of the world's total Muslim population; Pakistan has staunchly opposed the entry of India into the organization.


title: Organisation of Islamic Cooperation

text: Pakistan has cited its conflict with India over the Kashmir region as the reason for its opposition, and frequently accuses India of perpetrating widespread human rights abuses against Kashmiris in the Indian-administered territory of Jammu and Kashmir, which has witnessed an ongoing militant uprising since the 1980s. The OIC has been urged to press India on the Kashmir dispute, and has faced pushback from Indian officials for occasional references to Jammu and Kashmir as territory that is militarily occupied by India. Historically, the Muslim world has largely lent its support to Pakistan over India during any armed conflicts between the two states. Despite these issues, the first OIC summit held in 1969 in Rabat did not address the Kashmir dispute, and granting India membership in the organization was discussed nonetheless. The head of the Indian delegation, the then ambassador to Morocco, also addressed the gathering at the summit. The erstwhile President of Pakistan, Yahya Khan, reportedly expressed mixed views towards the induction of India into the OIC as a full member. The Indian delegation, led by the then Indian President Fakhruddin Ali Ahmad, was scheduled to arrive at the summit but ultimately was not allowed in due to threats by Pakistan to boycott the event, leading to controversy. Differences between the two states led Pakistan to keep India out for the final session of the 1969 conference and all OIC summits thereafter.


title: Organisation of Islamic Cooperation

text: On 14 February 2019, a suicide-bombing attack by a Muslim militant in Jammu and Kashmir killed over 40 Indian soldiers, and was claimed by Jaish-e-Mohammed, a Pakistan-based terrorist group. In March 2019, India conducted airstrikes in Pakistani territory, which subsequently led to the 2019 India–Pakistan military standoff.


title: Organisation of Islamic Cooperation

text: After these events, Indian Foreign Minister Sushma Swaraj was invited to participate in an OIC summit. However, Pakistan protested this development and demanded that India be blocked from the event, accusing the latter of an unprovoked violation of Pakistani airspace while Indian officials claimed that the strike was carried out on terrorist-training camps within Pakistan. Following requests by Pakistan shortly after the 14 February attack, the OIC held an emergency meeting on 26 February to discuss the Kashmir dispute. The organization subsequently condemned India's military response to the attack and advised both sides to exercise restraint.


title: Organisation of Islamic Cooperation

text: For the first time in five decades, the United Arab Emirates invited India as a "guest of honour" to attend the inaugural plenary 46th meeting of OIC foreign ministers in Abu Dhabi on 1 and 2 March 2019, overruling protests by Pakistan. Shortly afterwards, Pakistan boycotted the meeting objecting to the invitation of India. Indian Foreign Minister Swaraj served as the head for the Indian delegation and attended the summit.


title: Organisation of Islamic Cooperation

text: On 18 April 2020, the OIC had issued a statement, urging the Modi administration of India to take urgent steps to "stop the growing tide of Islamophobia", citing attacks by Hindu nationalists against Indian Muslims and the allegation against Muslims of spreading COVID-19 in the country (see Violence against Muslims in India).


title: Organisation of Islamic Cooperation

text: Cartoons of Muhammad, published in a Danish newspaper in September 2005, were found offensive by a number of Muslims. Third Extraordinary Session of the Islamic Summit Conference in December 2005 condemned publication of the cartoons, resulting in broader coverage of the issue by news media in Muslim countries. Subsequently, violent demonstrations throughout the Islamic world resulted in several deaths.


title: Organisation of Islamic Cooperation

text: OIC created the Cairo Declaration on Human Rights in Islam. While proponents claim it is not an alternative to the UDHR, but rather complementary to it, Article 24 states that "all the rights and freedoms stipulated in this Declaration are subject to the Islamic Shari'ah" and Article 25 follows with "the Islamic Shari'ah is the only source of reference for the explanation or clarification of any of the articles of this Declaration." Attempts to have it adopted by the United Nations Human Rights Council have met increasing criticism, because of its contradiction of the UDHR, including from liberal Muslim groups. Critics of the CDHR state bluntly that it is "manipulation and hypocrisy," "designed to dilute, if not altogether eliminate, civil and political rights protected by international law" and attempts to "circumvent these principles [of freedom and equality]."


title: Organisation of Islamic Cooperation

text: Human Rights Watch says that OIC has "fought doggedly" and successfully within the United Nations Human Rights Council to shield states from criticism, except when it comes to criticism of Israel. For example, when independent experts reported violations of human rights in the 2006 Lebanon War, "state after state from the OIC took the floor to denounce the experts for daring to look beyond Israeli violations to discuss Hezbollah's as well." OIC demands that the council "should work cooperatively with abusive governments rather than condemn them." HRW responds that this works with those who are willing to cooperate; others exploit the passivity.


title: Organisation of Islamic Cooperation

text: The OIC has been criticised for failing to discuss the treatment of ethnic minorities within member countries, such as the oppression of the Kurds in Syria and Turkey, the Ahwaz in Iran, the Hazaras in Afghanistan, the 'Al-Akhdam' in Yemen, or the Berbers in Algeria.


title: Organisation of Islamic Cooperation

text: Along with the revisions of the OIC's charter in 2008, the member states created the Independent Permanent Human Rights Commission (IPHRC). The IPHRC is an advisory body, independent from the OIC, composed of eighteen individuals from a variety of educational and professional backgrounds. The IPHRC has the power to monitor human rights within the member states and facilitates the integration of human rights into all OIC mandates. The IPHRC also aids in the promotion of political, civil, and economic rights in all member states.


title: Organisation of Islamic Cooperation

text: In September 2017, the Independent Human Rights Commission (IPHRC) of the OIC strongly condemned the human rights violations against the Rohingya Muslims in Myanmar.


title: Organisation of Islamic Cooperation

text: In December 2018, the OIC tentatively raised the issue of China's Xinjiang re-education camps and human rights abuses against the Uyghur Muslim minority. The OIC reversed its position after a visit to Xinjiang, and in March 2019, the OIC issued a report on human rights for Muslim minorities that praised China for "providing care to its Muslim citizens" and looked forward to greater cooperation with the PRC.