Types of fiber optic connectors
Since fiber optic technology was introduced in the late 1970s, numerous types of connectors have been developed, probably more than 100 types. Each new design tried to offer better performance (less loss of light and reflectance) and simpler, faster and/or cheaper terminations.
Of course, the market is the one that over time determines which are the effective connectors,
although several attempts have been made to standardize the connectors. Some are unique to certain systems or networks, for example, the FDDI (fiber-distributed data interface), the first LAN local area network, and the ESCON, the interface to connect the main servers ( mainframe ) from IBM to peripherals, they needed special connectors. The TIA 568 standard originally determined that SC
connectors were the standard ones, but then when users started using more ST connectors than SC and a new generation of smaller connectors was introduced, the TIA-568B standard was amended and established
Any connector that was supported by FOCIS standards was accepted.
The four connectors are seen here show how fiber optic connectors have evolved. The one below is a Deutsch 1000 connector, the first commercially available fiber optic connector. It was actually a mechanical joint, which held the fibers inside with a small nut that adjusted them. The piece that forms the nose had a spring, which allowed to expose the fiber to cut and join it, with plastic lenses in a coupling adapter. The coupling adapter also had a fluid index equalizer to reduce losses, but this caused a problem with dirt.
The AT&T biconic connector was developed by Bell Labs laboratories in the mid-1970s. The conical the splint was molded from a plastic filled with glass. The first bionics had splints molded into the fiber until they developed a fragment of 125 microns (0.0127 cm) exactly in the center. When the bionics were adapted for single-mode fibers, the splints were joined with a special grinding machine so that they were in the center of the fiber.
The SC connector, which was introduced in the mid-eighties, used a new invention, molded ceramic splint, which revolutionized the termination of the optical fiber. Ceramics was an ideal material for splints. They were made economically by molding, much cheaper than, for example, metal machining. It
was extremely temperature stable, had similar expansion characteristics to glass, which prevented the
"piston" when the splint took off, a problem that had metal or plastic splints. Its hardness was similar to glass, which made it's polishing much easier. In addition, it easily adhered to the fibers using epoxy or anaerobic adhesives. Currently, almost all connectors use ceramic splints, usually 2.5
mm in diameter (SC, ST, FC) or 1.25 mm in diameter (LC, MU connectors).
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