BICSI Insider

Volume 6 Issue 4

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Page 23 of 27

1. KNOW WHAT YOU'VE GOT Any singlemode fiber network in the modern era is likely to have at least two categories represented in it. The typical ITU G.652D fiber coming in from the outside plant is usually splicing to a bend- insensitive (ITU G.657A) premise cable or pigtail when it enters a building. And if it is going into a residential space, ultra bend- insensitive (ITU G.657B) fibers might be involved. Beyond that, with wide area networks and long-haul systems terminating directly into data centers, it is not unreasonable to expect that many a hardworking ICT tech will be exposed to some specialized long- haul fibers from the ITU G.654 or ITU G.655 categories. In all cases, it helps to know up-front what you are splicing. 2. CALIBRATE ACCORDINGLY "Calibrate," in this case, refers to both equipment and expec- tations. The odds of success increase dramatically if you are using modern splicing equipment that has seen the inside of a calibration lab and received the latest splice menu updates within the last twelve months. But even with that as a given, splicing dissimilar fibers will frequently create OTDR anomalies such as gainers or exaggerated losses depending on the direction of the trace. And in some cases, additional real splice loss should be expected when fiber types are sufficiently different. Your fiber vendor will have good information about expected splice losses and can provide guidance on what "reasonable" should look like. 3. USE THE RIGHT EQUIPMENT Fiber manufacturers have refined bend-insensitive fibers to the point that even the simplest fixed v-groove alignment fusion splicers can deliver reasonable results when splicing them to a standard (G.652D) fiber. But if you find yourself splicing to something more exotic from a long-haul network, the core-alignment machines can use a nice bag of tricks to mitigate some of the effects which contribute to splice loss. The major fusion splicer manufacturers will almost always have those splice menus preconfigured for even the oddest singlemode splice combination. But you may have to call tech support and arrange for a download of that menu if it is not already on your machine. 4. DO PROPER TESTING An OTDR trace from only one direction is just shy of useless when it comes to determining actual splice loss between two dissimilar singlemode fibers. A bidirectional average from the OTDR is always the recommended procedure. TECH TIP: "When Your Singlemode Fusion Splice Gets a Little Complicated" By Guy Swindell, RCDD, OFS Market Development Manager The ICT industry has a tendency to refer to singlemode optical fiber as if it is a single type of product. In reality, singlemode has evolved over many years into an alphabet soup of categories and subcategories that are suited for specific applications. This is never more apparent than when it comes time to splice. Page 24 EDUCATION

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