Manufacturers in all aspects of fibre technology have introduced products that offer increased performance and improved reliability at reduced cost. Transceivers are now far less critical to assembly tolerances; "universal" cables, equally suitable for internal and external use, have been developed by many manufacturers; fibre concentricity has improved to the point where splice and connector manufacturers can index on the cladding, and high performance low cost testing and measurement equipment is readily available.
The key measure for network installers is Total Installed Cost (TIC), the aggregate cost of the hardware itself and the labour costs incurred in dragging cables, terminating fibres, installing telecoms cabinets and configuring, testing and identifying the patch panels and cable runs. New products from the manufacturers of fibre optic connectors and splices are not only intrinsically less expensive than older models, they are also easier and quicker to use, reducing expensive on-site labour costs.
Different manufacturers obviously produce their own particular product solutions when considering the same problem. For instance, in splicing, 3M Telecom Systems developed the Fibrlok, a mechanical splice that was applied separately to each individual fibre, using a "clamshell" arrangement to lock the fibres into position. The Multi-Fiber Fibrlok followed, which enabled the operator to splice 12 individual fibres simultaneously. AMP's Fingersplice is a reusable tool-less splice that offers fast reliable splicing; it uses two annular sliding rings to close the splice. Their latest product, the Corelink, is even cheaper, easier and faster to use and provides improved protection against torsional failures; it uses a lever to close the splice. Siecor, another US manufacturer, has developed a cam-based mechanical splice that is rotated to close it. All these techniques have their strengths and weaknesses; the choice is largely dependent on the application. Manufacturers of fusion splicers such as Biccotest and Northern Telecom have drastically reduced the cost of the equipment in the last few years, often by as much as 70%.
It is the same story with connectors. Many manufacturers offer epoxy connectors in which the connector is secured to the fibre by epoxy adhesive; on-site, this was a cumbersome procedure involving mixing two-part epoxy, curing ovens, syringes and other tools. For large batch production of pigtails or patch cords in the factory, the traditional epoxy connector is probably still the best option, but on-site it has proved to be less than ideal. 3M Telecom Systems' Hot Melt epoxy connector reversed the normal procedure of terminating cables by pre-loading the connector body with the requisite amount of epoxy which was softened by heating prior to the insertion of fibre. This reduced termination time to around five minutes per fibre, and simplified the termination process to make it easier to use on-site.
"Crimp-and-cleave" epoxyless connectors are available from both AMP and 3M; however, as one would expect, the methods used to retain the fibre into the connector body are very different. In the AMP LightCrimp a sophisticated tool provides a two-stage crimp in one operation. The cleaved fibre is inserted through the connector body; in the first stage of the termination process a plunger is driven into a collar of resilient spheres that deform under the pressure, clamping both the buffer and the fibre cladding, thus ensuring a stable joint. In the second stage of the operation, the connector body is secured to the cable strength members, relieving the fibre from cable stresses. The new Crimplok connector from 3M Telecom Systems combines the proven V-groove technology used in the Fibrlok splice with the outstanding ferrule design of their epoxy connectors to achieve high optical performance with termination times of two minutes per fibre.
An alternative way to reduce TIC is to do away with on-site terminations as far as possible. BICC Brand-Rex's MTConnect system is based on a system of miniature modular MT connectors, originally developed by NTT in Japan and brought to Europe by a joint venture in which BICC is the majority partner. MTConnect enables pre-terminated structured cabling assemblies, fabricated to the required length off-site, to be pulled through cable ducts to the telecoms cabinets, where the cables are plugged directly into dedicated distribution enclosures or 19" patch panels. A similar system, using the same format connector, is the Meth-Net system offered by Methode Mikon. Meth-Net consists of wall-mounted or 19" patch trays, supplied ready fitted with a fanout assembly, available in all popular connector formats, and the network cables themselves, supplied in standard or custom lengths.
Advances in connectors, particularly in the design and material used for the ferrule, increased volumes and reduced assembly times have enabled costs to be dramatically lowered.While it is unlikely that patch cords will be superseded, easy-to-fit connectors mean that it is now a realistic (although probably not cheaper) option to do away with pigtails and splicing altogether. Traditionally in patch trays the breakouts from the backbone cable would be spliced to pigtails fitted with the appropriate type of connector. Now, by using Hot Melt, Crimplok or LightCrimp connectors, doing away with the splice is a practical option; the terminated pigtails are the backbone breakout fibres themselves. An alternative trend is for the patch panel to be preassembled as far as possible off-site, leaving only the splice to be completed as part of the installation. The Meth-Net system takes this idea to its logical conclusion, with a connector replacing the splice at the cable end of the tray.
The fibre market has grown from its initial specialist niche in long distance telecommunications, where the huge increase in bandwidth more than offset the considerable cost impact of introducing a new technology. It then became established as the preferred backbone medium in LAN applications, and the cost of components, cable and installation fell rapidly. Fibre is now entering the next phase of its development, where the latest round of new product introductions has paved the way for a far broader use of fibre in interconnection systems; uses that would have been precluded by cost considerations alone only a few years ago.
Graham Lipson is with Auriga (Europe) PLC.