9/25/2023 0 Comments Sma connector fiber![]() As the long-haul industry moved from multimode (MM) to singlemode (SM) fiber around 20 years ago, the reflections at SM connections caused big problems with most laser sources. The next confusing nomenclature for fiber optic connectors came from the polishing of the end of the ferrule, giving us “PC,” “Ultra PC” or “Super PC” and “APC” connectors. The connectors with two ferrules, one for fibers transmitting and receiveing in opposite directions, are called "duplex" connectors. The 2.5 mm ferrule was also used in the FDDI and ESCON connectors, both named for the systems for which they were designed. NTT responded a couple of years later with the “SC” or “subscriber connector” and the ST and SC dominated fiber optics for over a decade. Shortly thereafter, AT&T introduced the “ST” or “straight terminus” (contrasting to the “biconical” – get it?) that used exactly the same ceramic ferrule as the FC but replaced the screw-on nut of the FC with a bayonet lock like a BNC coax connector, simplifying and speeding up connector insertion. The “FC” or “fiber connector” from NTT (Nippon Telephone and Telegraph) was the first connector to use the 2.5 mm ceramic ferrule. The uneven expansion coefficients sometimes caused the adhesive to fail, allowing the fiber to extend or retract, a process called “pistoning.” The ceramic ferrule had a very low expansion, like glass, so the adhesive held better, the connector could be polished to a finer finish and performed better over extremes in temperature. Metal ferrules had a problem with glass fiber. The next major development in fiber optic connectors came from Japan, with the development of the ceramic ferrule. It was developed by Amphenol using the hardware from the “SubMiniature A” microwave connector, hence it’s name, with a precise 1/8 inch machined metal ferrule. The SMA connector was the first connector widely used for data links using multimode fiber. The original Biconic was actually molded around the fibers to get exact centering, a practice that stopped when they developed a way to insert a 125 micron ( 5 mil) pin in the plastic molding cavity to produce a connector ferrule with a hole into which fibers could be epoxied. Is the FOA Tech Topic that identifies most popular connectors from the history of fiber optics.) AT&T named their first commercial fiber optic connector the “Biconic” since the connector had a conical molded-plastic ferrule that fitted into a “bi-conical” mating adapter when connected to another connector. ![]() ![]() Some of you may remember the Biconic and SMA connectors which were the most popular connectors 25+ years ago. But we’ll also cover some important information about fiber optic connector design and termination along the way. Since some of us have been in the business for over 25 years ourselves, we do remember some of the origins of these terms and find it amusing to share the stories. Rarely do FOA instructors present a fiber optic seminar without getting some questions on what some connector terminology means or how such a term or connector name originated. ![]() ![]() The FOA Reference For Fiber Optics - Connector Types and TerminologyĬonnector Types and Terminology – What's In A Name? ![]()
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