Every fiber technician has heard the terms field polish and factory polish, but what is the difference and why does it matter so much which option you choose for your application? Well there are some big differences in many factors when you compare a field terminated cable and a factory terminated solution that comes ready to plug and play.

A termination is just a fancy way of saying that you are attaching a connector to some type of optical fiber; it can be singlemode or multimode fiber. The mode of the fiber only deter

mines what kind of connector you need but not the kind of termination you have to do. Each method has pros and cons to consider when you are choosing the method to use for your application. There are a number of factors that can affect why you would choose a particular termination method. If you are using a MTP or MPO connector it would most likely be wise to choose a factory termination because these connectors are complicated and do require a level of expertise. If you are using a more common connector style such as a LC, SC, ST or FC in your project you may be able to use a field termination method instead of outsourcing to a cable assembly house for a factory termination.

The options for factory terminations:

• Custom Manufactured Cable Assemblies or Stock Patch Cables
• Fiber Optic Pigtails
• Splice On Connectors

Factory Terminations

Custom Manufactured Cable Assemblies and Stock Patch Cables

Factory terminations typically utilize the traditional epoxy and polish method of assembly. Cable assemblies must be ordered at the length that is required to complete the fiber run. Factory polished assemblies usually have the best performance and they are held to stricter quality standards than field terminations, making them the best solution for applications that require low loss and high performance. Most assemblies that are factory terminated arrive with the manufacturer’s test results so you know that you are getting the best quality and excellent performance from the assemblies that you purchased.

Patch cables that are built to order by a cable assembly house can be customized to any special requirements that are necessary for your application. This makes them ideal for customers who need particular performance standards, or specialty fibers, or custom color jackets on their patch cords. These solutions usually reduce the time it takes to install them because when they arrive, they are ready to plug in and get right to work. The technician does not have to do anything to the patch cable except remove the ferrule protection cap and clean the connector end face. There is very little technical knowledge necessary; the tech only has to plug the assembly into the correct ports on the equipment and into the patch panel.

A possible down side of factory polished terminations is that they do require time to manufacture and lead times can be long, depending on the manufacturer. Also, the cost of the patch cables is typically higher because of the custom labor required to build an individual assembly to order. You should also consider network down time when making your decision. If you are in a situation that requires a quick response, such as in the case of a bad connector that needs immediate attention to get the network back online, you may not have time to wait for a custom manufactured assembly.

Fiber Optic Pigtails

A pigtail that will be spliced to existing fiber is also a factory polished connector but it is only terminated on one side of the fiber leaving the other side exposed for fusion splicing. Pigtails are a good, affordable option for technicians who have experience splicing fiber and also own a fusion splicer. Pigtails usually come in stock lengths and are available “off the shelf” in the most widely used connector styles. This does add a bit of additional time to a job, because of the splicing and labor involved in the process, but not as much time as it would take to install an epoxy and polish connector.

Splice on Connectors

Splice on Connectors are also a factory polished option. They can be applied in the field with the use of a fusion splicer and some consumables. They come in a variety of styles and in both single mode and multimode fiber types. SOC’s are quick and easy to install in the field, and they are available at an affordable price point per connector. They do require a fusion splicer and some additional tools to terminate, as well as some knowledge of the process of terminating a SOC (Splice on Connector). They are a single use connector. Once they are terminated they cannot be reused.

The options for field terminations:

• Fiber Optic Pigtails
• Splice On Connectors
• Mechanical Connectors
We have already talked about Pigtails and Splice on Connectors above. These factory polished options are most commonly attached to the fiber in the field so they also belong in the field termination category.

Field Terminations

Field terminations can also be done by using a mechanical connector. In this instance, the fibers are cleaved to a specific length and the field fiber is mated to the fiber stub inside of the factory polished mechanical connector with index matching gel. These connectors are fast and reliable for field terminations. They come in a variety of configurations for both multimode and singlemode applications.

Depending on the connector manufacturer, special tools are sometimes required to terminate mechanical connectors, and these tools can be somewhat costly. But once they are purchased, they have a long life and only the consumables need to be replaced.

Mechanical connectors are fairly easy to terminate and the process can be learned quickly by technicians in the field, but they do have a downside. These connectors have higher reflectance and loss than their SOC or pigtail counterparts. So if optimal performance is a necessity for your job, these connectors may not be the best solution.

Currently there are no MTP/MPO mechanical connectors on the market. The most likely reason for this is that MTP/MPO connectors have three accepted industry standard polarities. They are called Type A, Type B and Type C. Type A is also referred to as Straight Through. In this polarity Fiber 1 is in Position 1 in both MTP/MPO connectors in the cable assembly. The second polarity, Type B, is referred to as Reversed. This means that Fiber 1 is in the first position of one connector and in the twelfth position in the second connector. The last commonly accepted polarity, Type C, is called Flipped Pairs. In this configuration, Fiber 1 is in the first position in one connector of the assembly and in the second position in the other connector. Fiber 3 is in the third position in the first connector and the fourth position in the second connector, and so on.

Whether you choose a field or a factory terminated solution, each option has advantages and disadvantages as explained in the above passages. Hopefully, some of the information here can help you choose which of these solutions best fits your application.