One often needs a fast fiber optic termination. It’s not just when you are doing a large number of connectors, as in a computer facility or a telecomm room; sometimes it’s when you only need to do one or two, such as repairing a damaged connector or terminating one or two fibers at a location, as is often encountered with video systems or fiber to the desk.
Since speed has been an issue from the beginning, many different methods of fast termination have been tried, but most have been abandoned due to high cost or poor optical performance (loss and reflection). Factory-made terminations on patchcords are all made by the tried-and-true epoxy/polish method. The connectors are the cheapest (less than $1), the losses the lowest (<0.3 dB) and the yield the highest (better than 99 percent). But many installers shy away from epoxy/polish connectors in the field due to the equipment necessary and additional steps to mix, inject and cure the epoxy.
An alternative is to use a quick-curing adhesive, often called an anaerobic adhesive, that uses the same inexpensive connectors as the epoxy/polish method. You can inject the adhesive and use an accelerator to make the adhesive set in 30 seconds or less or simply wipe the adhesive on the fiber, insert it in the connector and wait 3 to 5 minutes for the adhesive to set. One of the best-kept secrets in fiber optics is the use of a simple, inexpensive adhesive, Loctite 648, for quick terminations. The whole process is detailed in Lennie Lightwave’s Guide To Fiber Optics (www.LennieLightwave.com).
Two other proprietary adhesive methods offer fast terminations. The 3M “Hot Melt” method uses connectors with adhesive already in the connector. You put the connector in a very hot oven to melt the adhesive, remove them and insert the fiber, let it cool and polish. A new development is the “Quick Assembly” from Huber+Suhner of Switzerland. It uses a powdered, heat-cured epoxy in standard connectors, but the big deal is a termination tool that looks like a Star Wars light saber. I’ve tried this one myself and it’s good. Although the termination tool is a bit pricey, it’s very cool looking.
The most widely known fast terminations are what insiders call “cleave-and-leave” connectors, but they may be better known as “prepolished/splice” connectors. They have a short fiber stub epoxied inside them and the ferrule has already been polished. The connection is made with a splice inside the connector. You only need to cleave the fiber and insert it in the connector, then crimp it and you are finished.
These connectors can work fairly well if the installer is well trained and the fiber is properly cleaved. Unfortunately, to keep termination kits reasonably priced, they include an inexpensive cleaver that is not the best. If the user practices with this inexpensive cleaver, he or she may get reasonable results. But substituting a good cleaver—about $1,200—and using a visible laser to monitor the process makes these connectors easier to terminate.
However, the cleave-and-leave connectors are not low-loss connectors. A connection includes not only the loss of the connector, but also the internal splice. While an adhesive connector will typically have less than 0.3 dB loss, these connectors are specified for 0.75 dB loss. A well-known fiber optic trainer—Eric Pearson, one of the real experts on fiber optic connectors—has experimented with these for use in his classes. His initial results were mixed, with connector losses varying from 0.3 dB to 15 dB and yields of less than 50 percent. Perfecting the process and using a very high quality cleaver gave better results, averaging 0.6 dB losses when using one particular manufacturer’s connectors. If an expert has this much trouble with these connectors, it should warn you to get good training before attempting to use them.
The rest of the quick terminations are a mishmash of crimp-and-cleave or crimp-and-polish techniques. Most are quick but high loss, primarily useful for temporary repairs. Many, from my personal experience, require a “feel” that only comes with good training and extensive experience.
The old adage “time is money” has double meaning when it comes to fiber optic terminations. The quicker connectors can save you labor costs, but the connectors themselves are much more expensive. While a simple connector for adhesive termination is about $1, the cleave-and-leave connectors are $10 to 15 and Hot Melts about halfway in between. You may find that what you save in labor cost is lost in connector cost, especially when you factor in yield. The difference between the high yield of adhesive connectors and the potentially poor yield of cleave and leaves can have a big effect on costs.
I’ll conclude with my standard warning—get good training. No matter what fiber optic termination style you choose, your success will depend on your process. Get good training from the manufacturer’s trainers (not just the salesperson!) and practice with your tools before you ever try to do a field termination. EC
HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at www.JimHayes.com.