Producing Effective Terminations

Some years back, fiber optic connector manufacturers started offering connectors that terminated fiber quickly without using adhesives or requiring polishing. The manufacturer glued a short stub fiber into the connector ferrule and polished it perfectly in the factory. The back of the connector was modified with the addition of a mechanical splice, complete with index-matching gel to reduce loss at the fiber interface and a crimp to hold the fiber. Terminating these connectors was super-simple: cleave the fiber, insert it into the connector, crimp it in place and you are finished. No adhesive, no polish.

Unfortunately, between the concept and the product, reality intervened. Economics caused the manufacturers to create termination kits with an inexpensive fiber cleaver, the key tool in terminating these connectors.

The quality of the fiber cleave was the most important factor in getting acceptable loss in the termination.

Then the sales and marketing department oversold the product, claiming an inexperienced installer could terminate a fiber in less than a minute saving lots of labor costs. However, the department did not mention the time needed for setup and cleanup, nor the necessity of training and practice to get a reasonable yield of good connectors.

As a result, a lot of installers got burned, and these connectors, now called “prepolished/splice” connectors, got a bad reputation.

After undergoing continual improvements, these connectors now offer a viable alternative to adhesive/polish connectors for knowledgeable installers who approach their use with care and know a few tricks of the trade.

These connectors will never have loss as low as an adhesive connector because they are actually an adhesive/polish connector with a mechanical splice inside them. The good news is the connector factory polish is first class, so the connector-to-connector interface has low loss, probably averaging better than 0.2 dB loss. The bad news is the splice can add 0.5 dB to the total loss of the termination, making them a 0.7 dB connector.

An instructor I know claims his students now achieve around 0.5 dB loss from these connectors, using an expensive ($1,200) cleaver typically used with fusion splicers. This cleaver produces consistent, high-quality cleaves to mate with the fiber stub in the connector.

The other point he makes is the fiber must be inserted into the connector and be kept under tension during the crimp process to make sure the two fiber ends in the internal splice stay in contact.

Using these techniques, his students have produced an excellent yield of connectors better than the TIA-568 standard requirement of 0.75 dB loss or less.

Some manufacturers of prepolished/splice connectors acknowledge these issues and are offering termination kits with precision cleavers and tools that carefully hold the fiber and connector during the termination process.

Another trick in using these connectors is to visually confirm the quality of the splice. A visual fault locator (VFL) with a bright red laser can be used to optimize the internal splice.

The light lost in the splice is visible through the body of the connector, so one can confirm the splice is good when the red light is minimized. Adding a VFL to your toolkit along with a precision cleaver is another necessity.

Perhaps you already guessed my next recommendation: it is mandatory to get good training on the termination process for these connectors, even if you are already familiar with adhesive/polish connectors.

Most manufacturers’ termination kits include special tools for holding and crimping the connector, as well as an inexpensive cleaver that should be traded in for a better model.

It is absolutely mandatory to get trained on the use of these tools and the exact process recommended for termination. And, of course, you should practice enough with these connectors to become proficient in their use before bidding or using them on a job. The economics of these connectors depends heavily on the yield of good connectors during installation.

When a prepolished connector costs $10 to 15 or more, compared to an adhesive connector at $1 to $2, it is critical to make sure every connector installed is a good one. That is why a $1,200 cleaver, a $500 VFL and a couple of days training is a worthwhile investment. Producing 100 more good connectors will pay for the tools or the training.

Only when an installer can equal the yield of adhesive/polish connectors can a direct comparison of installed costs be made. Then, the advantages of these connectors’ fast termination times can be fully exploited to save labor costs in any project. EC

HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at


About the Author

Jim Hayes

Fiber Optics Columnist and Contributing Editor
Jim Hayes is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at .

Stay Informed Join our Newsletter

Having trouble finding time to sit down with the latest issue of
ELECTRICAL CONTRACTOR? Don't worry, we'll come to you.