The NEC D4 Fiber Optic Connector was probably the first connector to use ceramic or hybrid ceramic/stainless steel ferrules. It uses a smaller ferrule than SCs or FCs. It was widely used in telecom networks in the 80s to early 90s and some may still be in use.D4 connectors are made from a 2.5mm diameter ceramic (zirconia) ferrule for durability. They have a high-performance threading mounting system and a keyed body for repeatability and intermateability. D4 connector is one of the older generation connectors which is keyed, and spring loaded and has a 2mm diameter ferrule. Connector body is nickel plated brass for enhanced durability.
- Bore diameter: 125-2500um
- Fiber type: multimode
- Ferrule material: stainless steel or beryllium copper
- Boot size: 3.0mm
- Materials Processing
- Laser marking, cutting and welding
- Laser surgery (including cosmetic surgery, eye surgery, tattoo removal)
- High power spectroscopy
- Light detection and ranging (LIDAR)
- Non-linear optic
In the development of fiber optic technology over the last 35 years, many companies and individuals have invented the “better mousetrap” – a fiber optic connector that was lower loss, lower cost, easier to terminate or solved some other perceived problem. In all, about 100 fiber optic connectors have been introduced to the marketplace, but only a few represent the majority of the market.
The most popular connectors are covered in the TIA connector intermateability standards FOCIS-x (TIA-604-x).
Since the earliest days of fiber optics, orange, black or gray was multimode and yellow singlemode. However, the advent of metallic connectors like the FC and ST made color coding difficult, so colored boots were often used. The TIA 568 color code for connector bodies and/or boots is Beige for multimode fiber, Blue for singlemode fiber, and Green for singlemode APC (angled) connectors.