Q: What are the differences between single circuit and single element fibre management?

A: Single circuit fibre management splits the cable element into individual or pairs of fibres (i.e. transmit and receive). This isolates each individual fibre or pair of fibres from other fibres / circuits held within in a cable element by storing them in individual splice trays. Splitting the fibres into single circuit allows easy distribution of the circuit into the network and offers an excellent point of flexibility.

Single element management allows storage of up to12 fibres per splice tray (i.e. 6 circuits) and increases the capacity of the connectivity equipment. Single element management offers less flexibility over the routing and maintenance of the individual circuits / fibres but an increased fibre splice density is achieved.

Q: Why should I choose to manage fibre on a single circuit basis?

A: Single circuit management allows isolation of individual customers and hence reduces the risk of interference with adjacent fibre circuits in case of maintenance / reconfiguration of the network. This is particularly important when transmission rates are at high bit rates. Single circuit working also allows individual fibres / circuits to be assigned to individual customers and distributed out from the cable element to offer flexibility when routing.

Q: Do Prysmian provide solutions for both single circuit and single element fibre management ?

A: Single element and single circuit solutions exist within the OAsys product range for all areas of the network build.

Q: What is a patch cord?

A: A patch cord is an optical cable used for linking (or patching) between optical sources. Demountable optical connectors (Terminations) are fitted to each end of the cable. The connectors may be either of the same type or alternatively have a different connector type fitted to each end. Patch cords may sometimes be referred to as either SIMPLEX or DUPLEX.

• SIMPLEX - refers to a Single Fibre Cable (SFC) with a single termination at each end

• DUPLEX - refers to a Double Fibre Cables (shotgun or zipcord) with double terminations at each end.

Q: What is a pigtail?

A: A pigtail is an optical cable link used for connecting between optical sources. A demountable connector is fitted to one end of the cable and the opposite end is fusion spliced on to a network fibre.

Q: What does the term Insertion Loss (IL) mean?

A: This is the measure of light lost at the connector interface in decibels (db). The loss is usually quoted as per mated pair of connectors.

Typical IL values would be 0.2db to 0.5db depending upon the Fibre and Connector type.

Q: What does the term Return Loss mean?

A: This is a measurement of light "reflected" from the Connector Face and returned back down the fibre, sometimes referred to as "Back Reflection Loss". Return loss is measured in decibels (db) and is always quoted by the manufacturer for Single Mode Fibres as the light returned/reflected back to the origin can affect the Laser producing the light and causing "noise" problems.
Typical RL values would be between 30db and 60db depending upon the Connector Type and end face finish polishing. The higher the Return Loss figure the better the Connector as this indicates the level of light returned down the fibre. Return Loss (RL) is never quoted for Multi Mode Fibres generally because the Light Sources used in MM systems are LED's.

Q: What types of connectors are available?

A: Many different types of connectors are used throughout the world but the most common are detailed below:-

ST (Straight Tip) - most commonly used for Multi Mode fibre systems, the connector provides Physical Contact (PC) properties by spring loading of the ferrule. A bayonet keyed fixing method maintains accurate alignment of the ferrule. They may also be used for some Single Mode Fibre systems where high Insertion Loss (IL) and low Return Loss (RL) can be tolerated. Available only as simplex connectors.

FC (Fibre Connector) - most commonly used connector for low loss Single Mode Fibre systems but also used for Multi Mode systems as well. Physical Contact (PC) properties are maintained by spring loading of the ceramic ferrule. Accurate alignment is maintained by the use of key way and threaded connector retention. Most optical test equipment, such as OTDR's, are fitted with FC connection output facilities to maintain accuracy of measurement. Available only as simplex connectors.

SC (Subscriber Connector) - Next most commonly used connector, to the FC, for Single Mode Systems but also used for low Insertion Loss (IL) multimode systems. Offers higher packing density of connectors in a patch panel with quick make and break connections. Physical Contact (PC) properties are maintained by spring loading of the ceramic ferrule. Accurate alignment is maintained by use of key way and push in connector retention. Used in preference to FC connectors as the adapters for the connectors are less expensive. Available in both Simplex and Duplex formats.

E2000 Connector - Becoming more commonly used within Fibre networks particularly in continental Europe . Generally only used for Single Mode systems. Very similar in operation to the SC but has built in end face covers that automatically open on connection in to the adapter and protect personnel from eye damage due to high intensity LASER light. Provides a more secure locking system than SC types. Connectors are more expensive than either FC of SC types. Available in both Simplex and Duplex formats.

DIN Connectors - Manufactured in accordance with DIN 47256 and the connector offers similar features to the FC type connectors. Connectors are of a more compact design than FC types and therefore offer a higher density of Patch panel population. The cost of the connector can sometimes be prohibitive, 2 to 3 times greater than the cost of FC connectors. Available as Simplex connectors only.

LC (Lucent Connector) - Similar to SC types but a more compact design and it offers a pull proof design mechanism. Sometimes referred to as Small Form Factor (SSF) Connectors. Connector cost generally more expensive than SC types. Available in both Simplex and Duplex formats.

Q: What is meant by the connector end face type and finish?

A: The IL and RL measurements can be improved by altering the contact surface between the fibres and connector. Surfaces can be cut at different angles, and polished to different levels. The different types of finish available are detailed below.

PC (Physical Contact) - Most generally used end face finish for all connector types. The connector is supplied with a polished radiuses convex face to give Physical contact at the fibre core interface.

Insertion Loss <= 0.4db

Return Loss >= 30db

SPC (Super Polished Physical Contact) - End face shape is the same as the standard PC connector but and additional fine polish is applied to the face of the connector to improve both insertion and return loss.

Insertion Loss <= 0.3db

Return Loss >= 45db

UPC (Ultra Polished Physical Contact) - End face shape is the same as the standard PC connector but and an extra fine polish is applied to the face of the connector to improve both insertion and return loss. All Prysmian Patch cords and Pigtails are supplied to this standard.

Insertion Loss < 0.3db

Return Loss >= 50db

APC (Angle Polished Physical Contact) - End face geometry is changed to produce an angled end shape (usually 8 0 ) and polished to UPC standard. This improves both IL and RL of the connector and makes them suitable for high quality low loss Single Mode systems. APC connectors are used exclusively for Single Mode systems. Connectors are identified with a GREEN colour code either on the connector body or boot. In general APC format connectors are limited to FC, SC and E2000 types. Special colour coded adapters are also available for these connector types.

Insertion Loss < 0.3db

Return Loss >= 60db

Q: What are Adapters (or Uniters )for connectors?

A: Adapters (sometimes called uniters) are used to link together two connectors of the same type or of different types.

A variety of adapters are available for all connector types to fit either pre-cut holes in patch panels or for bulkhead applications. Hybrid adapters are also available these allow connectors of different types to be connected to each other e.g. ST to FC, FC to SC etc.

The adapters are provided with an internal split sleeve to provide an accurate fit on the connector ferrule. Two types of sleeve are available either Phosphor Bronze or Ceramic (Zirconia), there is very little to choose between the sleeve materials but where high make and break of patched circuits is likely then Zirconia sleeves offer better wear properties. All standard adapters supplied by Prysmian have Ceramic Zirconia sleeves.

SC, LC and E2000 adapters are supplied with colour-coded bodies to indicate the Fibre Type or connector format; some of the most common colours are shown below.

• Beige - Multi Mode.

• Blue - Single Mode PC, SPC, UPC.

• Green - Single Mode APC.

Adapters for FCAPC applications are supplied with GREEN end caps to indicate that they are suitable for APC connection.

Q: What type of splice trays do the OAsys® products contain?
A: A variety of splice trays are used within the product range which are designed for optimum use within the product space, and also for its specific application. All splice trays are designed to actively manager the optical fibre to a minimum bend radius of 30mm. Most of our products contain one of two splice trays:

OAsys® Splice tray single element - Capacity up to 12 splice protectors, ability to store dark fibre in central mandrel, bend managed at all points to Ø60mm, One entry port, One exit port. In addition to the splice tray a variety of manifolds are available to manifold and distribute the fibres.

SSF12 Splice Tray - Capacity up to 12 heat shrink or crimp splice protectors or 6 Mechanical splices. Ability to store dark fibre in central mandrel, bend managed at all points to Ø60mm. Up to 6 entry / exit ports to accommodate a variety of tube types from Ø0.9mm to Ø5mm. A Clear plastic removable cover offers effective protection to the fibre.