Issue link: https://www.e-digitaleditions.com/i/1386104
July/August/September 2021 I 13 The pre-terminated cable assembly remains a very good option for higher-speed data centers. DATA CENTER FIBER TERMINATION TRENDS The health of existing connections can either help or hinder efforts for building the right data center fiber network. One issue that frequently arises is existing connections that are scratched or chipped. In these cases, three common options are available: • Field Polishing With field polishing, contractors individually polish the connectors. This is not a very popular practice because there are many downsides. It can be very time-consuming; it is viable only if a few connectors are chipped; and it is craft sensitive. This polishing method can also be difficult to achieve the 35 dB return loss requirement for singlemode connectivity. If polishing is an option, it is recommended to invest in an optical time domain reflectometer (OTDR) to measure optical reflectance. Some technicians often do not use an OTDR. Therefore, poor reflectance is usually found when a problem arises. • Fusion Splicing Terminations Unlike mechanical splicing that only aligns and does not physically join fibers, fusion splicing provides a permanent fusion connection between fibers. It offers typically a loss of 0.1 dB or less versus mechanical splicing's typically higher insertion loss of between 0.2 dB to 0.75 dB. Although mechanical splices can be valuable for certain applications, the fusion splicer can estimate the loss of the fusion splice, and it reduces uncertainty compared to mechanical splicing or field polishing. For these reasons, coupled with the steady decrease of fusion splicer prices, splicing pigtails and splice-on connectors (SOCs) have quickly become popular termi- nation options. Pigtails contain factory pre-polished connectors with a short fiber stub that can be fusion spliced to the incoming fiber from a trunk cable, for example. The splices are then protected within a splice sleeve and are stored in splice trays or cassettes along with any slack fiber. The SOC includes a factory pre-polished ferrule and a shorter fiber stub that is housed within the protective sleeve of the connector and eliminates the need for splice trays. A November 2019 in-house survey of industry professionals found that 59 percent of respondents were terminating singlemode fiber using fusion splicing solutions, higher than other termination options. 2 Most quality fusion splicers have become comput- erized with a multitude of features that optimize accuracy, speed, and more. Mass fusion splicers are no exception, with many quality models boasting a splice time of 11 seconds and typical loss of only 0.05 db. The primary benefit of mass fusion splicing is that it is much quicker and more productive to splice up to 12 fibers than performing all single fusion splices on an MPO pigtail for today's high-speed, high-density applications. • Factory Terminated Assemblies Of course, the pre-terminated cable assembly still remains a very good option for higher-speed data center networks, especially for large data center deployments. If a project involves hundreds of fibers, the reduced amount of time associated with pre-terminated cabling to project completion becomes very appealing. Some manufacturers have introduced newly designed flexible MPO connectors for their assemblies that allow gender and polarity change in the field. If the project is operating to tight loss budgets, pre-terminated fiber cable is also far more predictable, as the entire assembly has been tested in the factory. Managers do need to be confident in the length required for a cable and assured in the overall design, so factoring in slack may be necessary. Whether adopting pre-terminated cable assemblies, fusion splicing methods, or using another termination option, it is vitally important to consider how they may affect the loss budget and the project's total installed cost (TIC).