Which Termination for Your Connector Choice?

May 23, 2019

The method that you choose to terminate fiber has greater impact on a loss budget than your choice of connector!

In this article we will talk about the various termination methods for your connector choice. The termination method you choose is just as important your connector choice.

For a true estimate of connector loss you must add to that value the additional loss produced by the termination method that you choose, which for the sake of discussion we will call “termination loss.” This additional loss occurs at the point where the connector is joined to the field fiber. Most fiber optic connectors fall into one of two categories; they are either “quick termination connectors” or they are “epoxy style” connectors.

Interface Loss + ‘Termination Loss’ = True Connector Loss

COMMON TERMINATION METHODS

Connector Termination Options

For a true estimate of connector loss you must add to that value the additional loss produced by the termination method that you choose, which for the sake of discussion we will call “termination loss.” This additional loss occurs at the point where the connector is joined to the field fiber. Most fiber optic connectors fall into one of two categories; they are either “quick termination connectors” or they are “epoxy style” connectors.

Quick Term vs. Epoxy Connectors

Which is Better?

Quick Termination Connectors and Epoxy Connectors each have their own advantages and disadvantages, depending on the application and options you choose.

QUICK TERM CONNECTOR OPTIONS

“Quick-term” connectors provide a “quick” way to terminate fiber. These connectors are available with factory-polished ferrule endfaces, so no time is required for field polishing. Also, they do not require time to cure epoxy.
Quick term connectors offer two main options:

QUICK TERM OPTION 1

“Mechanical” Quick-Term Connector

Most “mechanical” quick-term connectors use a mechanical device to hold or “splice” the field fiber to a fiber stub within the connector body. These connectors are great when...

Speed is of the essence, e.g. emergency restoration
Installers do not have the skill or experience to assemble and hand polish connectors in the field
Fusion splice connectors and equipment are not available

“Mechanical” are available from a variety of manufacturers Including:

UNICAM Pretium from Corning
FIS Bobtail Connector from Fiber Instrument Sales
AFL Fast Connectors
Sumitomo Mechanical Field Connectors

QUICK TERM OPTION 2

"Splice-On" Connector (SOC)

Similar to “mechanical” quick term connectors, SOC quick-terms have a factory-polished fiber stub within the connector body. The difference is that SOC’s use a fusion splicing process to join the fiber stub to the field fiber instead of mechanical means, resulting in lower loss.

SOC’s typically have lower loss than field-polished epoxy connectors. The factory polish on an SOC is of higher precision than that which can be achieved by hand polishing in the field.

Insertion Loss Comparison (mated pair):

Factory-Polished SOC Connector: Mating Loss .4 dB + Per Splice Loss<.05 dB = .5 dB total loss

Field-Polished Connector: Mating Loss .75 dB + 0 Splice Loss = .75 dB total loss

SOC’s are an excellent way to achieve low-loss connections they...

simplify cable management
there are more installer options
they are easy to install
fusion splicers notify installers of a successful splice.

SOC’s are available from a variety of manufacturers including:

Fiber Instrument Sales Cheetah SOC
AFL (FuseConnect )
Sumitomo (Lynx 2)
Fitel and Seikoh Giken also offer SOC’s

EPOXY CONNECTOR OPTIONS

With epoxy connectors, the field fiber is permanently bonded to the connector ferrule, providing a very reliable connection. Epoxy connectors offer two options:

EPOXY OPTION 1

Field Polished Connector

With this termination method, the field fiber is routed through the connector body and ferrule, then field-polished as part of the ferrule endface. Since no splicing is involved, there is no “termination” loss as defined earlier.

Advantages:

Capable of low insertion loss and low back reflection
High quality and reliability when installed properly
Lowest cost per connector

Disadvantages:

Special tools for curing epoxy and hand- polishing
Long assembly time (including epoxy cure time)
High level of training is required
Precise endface geometry difficult to achieve by hand polishing

Most field-polished epoxy connectors use industry-standard epoxy. The 3M Hot Melt Connector uses a proprietary adhesive that does not require curing time.

EPOXY OPTION 2

Factory Polished Connector

Epoxy connectors can be purchased with factory-polished endfaces and are typically sold as...

Pre-terminated Cable Assemblies – Custom cable assemblies pre-terminated with connectors of your choice.

Connectorized Pigtails – Factory-polished connectors can be purchased that have attached pigtails for splicing to the field fiber.