For Immediate Release
November 10, 1997
NTT Optical Connectors Made International Standards
Five optical connectors developed by Nippon Telegraph and Telephone Corporation (NTT) have been established as international standards by International Electrotechnical Commission (IEC). In total, eight optical connectors for joining fiber cable and other optical equipment were designated by the IEC as new international standards, including SC, DS, MU, MT and MPO types developed by NTT.The standards will globally unify the sizes and designs, as well as cut the costs, of these connectors and other connection equipment, which will help to boost the diffusion of optical networks, such as those being used in NTT's fiber-to-the-home (FTTH) projects.
The IEC, an international organization comprised of representatives from approximately 50 countries, promotes the standardization of electric and electronic technology. NTT developed 17 of the 23 optical connectors examined. Moreover, of the 20 optical-device passive parts included among the items examined, the IEC's Japan representative is in charge of standards for roughly one-third of the devices, reflecting Japan's strong presence in this field.
Background
Optical connectors - basically plugs that join optical fibers - are essential devices in virtually all optical networks. They incorporate a high level of technical precision to connect extremely small optical fibers. At the same time, however, they must be made available at low cost for mass use. Demands are increasing for optical connectors used in optical local area networks (LANs) and to link high-speed computers.
Technical Features
In order to qualify as international standards, optical connectors must precisely join optical fiber cores, the part light passes through, which measure just 0.009 millimeters in diameter. For this, a connector must fit together with its mated ferrule - the cable part that surrounds the optical fiber - with a maximum deviation of 0.0001 millimeters. Moreover, the ends of the ferrule and the optical fiber must not be separated by more than 0.00005 millimeters.
Additionally, the ferrule and its mated connector of NTT developed optical connectors have been made to retain their physical shape despite changes in the environment, such as temperature, to ensure high reliability.
NTT Optical Connectors Chosen as International Standards
1. SC type:
Connects optical fiber cables one-by-one via a ferrule measuring 2.5μ diameter. A basic optical connector manipulated with a simple push-pull operation.
2. DS type:
Similar to the SC type, but used to connect optical equipment.
3. MU type
Joins optical fiber measuring 1.25μ in diameter (smaller than that joined by the SC type), which is used mainly to transmit light signals in physically limited spaces, such as inside equipment.
4. MT type:
Incorporates a rectangular plastic ferrule to simultaneously connect up to 12 cores in ribbon-type optical fiber, used mainly in underground sites.
5. MPO type:
Similar to the MT connector, easily connects ribbon-type multiple-core optical fiber with a push-pull operation, used mainly in buildings.
Future Developments
Current technology is focused on continually minimizing the size and cost of optical connectors, including cutting the number of connector parts, as well as simplifying the methods required to handle them. NTT is, for example, developing a simplified optical receptacle by drastically reducing the number of parts in its SC-type optical connector, as well as developing an advanced MT-type optical connector that connects from 16 to 80 cores in optical fiber. It is expected that such efforts will advance the development of optical, particularly fiber-to-the-home (FTTH), networks.
