Connector technology evolving to avoid pressure damage


Craig Millward, CEO Europe at Honda Connectors, Swindon, UK, outlines the technical challenges in next-generation optical networks that have led to the latest developments in optical connectivity solutions.

By addressing the challenges facing next-generation carrier-class optical networks, the emerging connector technologies are opening up the optical domain to a wide variety of applications, which have hitherto been too costly to be viable.

When a large number of fibres are terminated on the backplane, stresses are set up that can act to warp the backplane resulting in excessive mating forces between the optical fibres. This excessive force damages the internal structure of the connector, and the critical end-plane of each fibre with an effect called "chipping".

Currently, the most widely deployed optical connector is the SC-type family. However, Honda Connectors patented the technology for its new generation MU standard as long ago as 1988, and the infrastructure lifecycle is now seeing carriers and infrastructure owners ready to deploy MU technology in new installations. MU addresses chipping and reduces the losses that must otherwise be "tuned-out" when using SC type connectors. It delivers these benefits in a small form factor; the cross sectional area is 25% of a comparable SC connector.

Integration of coax & fibre connectors
Honda Connectors' FXMU series of coaxial plugs, jacks and adapters has the same footprint as its high-density MU optical interconnection systems, enabling integration of copper coaxial and fibre-optic cabling in the same interconnection scheme or back-plane.

A vertical two-contact housing can accommodate both coaxial and high-density fibre, allowing complex mixed connectors to be made, such as relay-style connections (plug-adapter-plug) and high-density plug-in connectors (backplane-package).

The interconnection system comprises a single-contact coaxial plug, high-density plug-in jack, single-contact coaxial connector and H-type vertical two-contact adapter.

Standard coaxial connectors consist of a MU-type plug combined with the single-contact adapter, while plug-in connectors are assembled by adding backplane and package housings to the MU-style coaxial plug and jack.

The same push-pull locking mechanism as optical connectors.

Fibre connectors
Fibreco offers a range of connectors for terminating both buffered fibre and tight-jacketed cable of 2.4 or 3.0mm diameters, comprising:

  • STII single-piece connectors;
  • SC two-piece connectors, available in simplex and duplex formats;
  • FSMA 905 single-piece connectors intended for 125µm multimode fibre (as are the FSMA Bulkhead Adaptors);
  • FC/PC Connectors, which are fully interconnectable with NTT-FC type products and available either pre-assembled or unassembled to ease optical performance tuning.

The connectors use pre-radiused zirconia ceramic ferrules. The spring-loaded ferrule is separated from the cable strain relief, preventing ferrule end separation when the cable is pulled.

OptiCon connectors
Designed specifically for distribution applications, KITCO's ST OptiCon connectors have a bayonet coupling and are fully compatible with existing ST hardware. Zirconia ceramic ferrules with pre-radiused end finish improve optical performance.

The connectors are made from nickel-plated copper alloy by mechanical turning rather than casting, increasing precision and durability.

Epoxy or anaerobic termination and double crimping (of the jacket and aramid strength member) ensures the quality of the construction.

Multimode and single-mode versions are available.

KITCO's SC OptiCon's are designed specifically for CATV and network applications and are fully compatible with existing SC hardware. Push-pull coupling mechanism is convenient for frequent switching. Like the ST connectors, SC Opticon connectors also feature zirconia ceramic ferrules with pre-radiused end finish. Angle PC is available for the better return loss. Epoxy termination and double crimping (of the jacket and aramid strength member) ensures the quality of the construction.

Different body colours indicate the type of the connector; the coupling clip easily configures two SC connectors to duplex format.

Fibre components
France's Rubis Precis specialises in high-precision components in high-tech materials such as fine ceramics, synthetic sapphire or ruby, fused quartz, optical glasses, tungsten carbide, stainless steel, titanium, and complete precision assemblies.

Recently developed fibre components include:

  • ruby jewelled ferrules for connector applications;
  • sapphire or glass balls and lenses for high concentration;
  • sapphire or zirconia cutting blades for slicing optical fibre;
  • ceramic vee block for fusion splicers.

1W attentuators
FibreFab Ltd has introduced its Optronics single-mode fibre attenuators for use with high-powered lasers in long-haul telecoms systems without the need for filters, airgaps or core mismatching.

Power levels are up to 1W and attenuation levels 1-30dB in fixed format. Back reflection is <-50dB (UPC) and -60dB (APC), and polarisation stability within 0.1dB PDL.

Fibre sees round corners
Cyber Operations is offering what it claims is the industry's first 90° connector, enabling miniaturisation, a 90% reduction in the cost of connection, and under 1dB loss.

Cyber's Snapticals connectors reduce costs by eliminating the need for skilled installation technicians and speeding up the connection-making process. Fibre no longer needs to be wrapped in large circles to go around corners, reducing the amount of fibre needed. At 2mm, the connectors can fit inside electronic components such as optical backplanes.

Atlantic Vision's connectors
Atlantic Vision is offering a large range of connectors including the following types: SC, FC, ST, LC, D4, E-2000, MU, MTRJ, and Biconic connectors for both multi-mode and single-mode fibre. Single-mode connectors are available with both 125um and 126um ferrules.

All Atlantic Vision connectors meet Bellcore certification criteria. The SC connectors are available in a wide variety of colours and boot sizes.

Corning Cable Systems' UniCam LC is for higher-performance, field-installable, small-form-factor, multimode and single-mode connector requirements. Quick installation (2.5 minutes for two connectors) reduces total installed cost of connectorisation.

The single-mode UniCam LC is the only pre-polished end-face, field-installable connector that can guarantee reflectance performance in the field. The UniCam incorporates a fibre stub fully bonded into the 1.25mm diameter ferrule. The other end is precisely cleaved and placed into the alignment mechanism of the mechanical splice. Both are fully protected from environmental factors. Unlike other no-epoxy, field-installable connectors, the UniCam LC requires no polishing.

Small form factor doubles density. Two LC connectors fit in the same space as a typical SC connector. Single-mode reflectance performance is <-50dB,

MU and LC connectors
Seiko Instruments GmbH says that both its MU and LC Connectors are available with Angle PC polish application, with ferrules and housings made by Seiko.

The MU Simplified Connectors are designed to save space. A zirconia slit sleeve is used, and the available inner hole diameter of the plug is 125µm and 126µm. Simplex, Duplex, 4-ports, 8-ports and 16-ports versions are offered.

MU Plug-in connectors are designed for high-density back-board interconnection. Duplex and 8-ports housings are available, as well as MU sleeve holder and MU Jack Housings for Ø 0.9 mm buffer cables and Ø 2.0 mm cords.

Seiko's range covers SC, FC, ST, MU, LC, MTRJ and E2000 connector types with PC, SPC, UPC and Angle PC polishing applications.

Ruggedised connectors
Deutsch Ltd's Ruggedised Singleway Connector range of high-performance connectors is made from Arcap for corrosion resistance and features a rugged construction incorporating environmental sealing and an anti-vibration coupling mechanism. The optical contact is spring loaded and common to both plug and receptacle to maintain physical contact even under severe shock or vibration.

Fibre faces are easily accessible for cleaning purposes. A choice of six alternative shell keyway orientations provides protection from inadvertent mis-mating.

Cassette-type fibre connector cleaners
NTT-ME has added innovative cassette-type connector cleaners for multi-fibre connectors with pins to its line of Cletop series.

Each rubber pad in the cassette is designed to match the width across pins of the MPO/MTP and the MT-RJ Connectors and the plain-woven ultra-fine micro-fibre replacement tape is also prepared. They enable the connector end-face to be cleaned easily and smoothly between the pins without damaging them.

Making connections
FiberSource Inc is offering a range of new connectors: The ST Connector, with ST-style bayonet coupling, nickel-brass coupling nut and body, pre-radiused zirconia ferrule, and fold-back style crimping for easy termination, is designed for PC, Super PC or Ultra PC applications. The ST meets EIA/TIA specifications.

The FC Connector is available in pre-assembled and parts versions, with pre-radiused zirconia ferrule, metal housing, and strain relief for 3.0mm). It also meets EIA/TIA, IEC and JIS C5970 specifications, and BellCore mechanical requirements.

The SC Connector, a one-piece, easy-assembly connector with pre-angled zirconia ferrule, is fully compliant with the IEC-SC/APC connector.

The LC Connector is a Lucent-licensed connector designed to minimize assembly time. FiberSource also offers MU Connectors.

AMP's range of connectors
AMP's fibre-optic connector range includes FC-type and D4 connectors, FSD, FSMA and mini-BNC connectors, IBM-approved ESCON Connectors and accessories (formerly RSD connectors), SC- and ST-style conectors, MT-RJ connectors, and MU high-density connectors.

AMP also supplies a termination/ professional installer kits and accessories and AMP LIGHTRAY MPX housings, coupling adapter and evaluation kits.

In addition, AMP supplies single or multi-port duct liner (OptiDuct), hybrid adapters, fibre-optic backplane connectors, and an expanded beam fibre connector/cable system.

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