Rise of the Splice Machines | Pigtailed Cassette-based Termination | Corning

By Ray Barnes
Appearing in Cabling Installation & Maintenance | Summer 2020

In the early days of optical fiber termination, direct termination using a factory-polished mechanical splice connector or field polished connector was not possible. Field termination required the use of a factory-polished connector with an optical fiber “tail” that was stripped, cleaned and cleaved, inserted into a fusion splicer and fused onto the field fiber, creating a “pigtailed” termination. This was a tedious process that required great precision and, until recently, hasn’t changed very much in 50 years. During that time, factory-polished mechanical and fusion splice connectors became available. While there are still optical fiber termination methods that rely on field polish of the optical fiber at the point of installation, the dominant technology today is the polish of optical fiber connectors in the controlled manufacturing environment. Even connectors that are field installable often have their fiber endface prepared in the controlled and repeatable environment of the factory. From the no-epoxy/no-polish connectors like the Corning UniCam, Panduit OptiCam or CommScope Qwik Connectors to the newer splice-on connectors such as the Corning Fuselite, AFL FUSEConnect or Belden FiberExpress Fusion, all these connectors share the distinction that their endfaces are factory prepared. Furthermore, all these methods share this distinction with one of the newest and most reliable termination methods—the cassette-based pigtail splice. This is a technology less than a decade old that combines the splice tray, adapter panel, pre-stripped and routed pigtails and splicing consumables required for optical fiber termination in a single compact cassette. In this article, we will examine the factors that have put this exciting new termination method at the forefront of optical termination methods.

In contrast, multimode fiber has progressed through OM1, OM2, OM3, OM4, and now OM5 with the latest generations promising increased reach and bandwidth. However, these fibers have not surpassed the performance of singlemode fiber in these respects. Many in-building and campus network owners and end-users have chosen to get off this multimode fiber generation treadmill by simply adopting singlemode fiber throughout the optical network. There has historically been an emphasis on using fusion splicing for singlemode fiber to minimize insertion loss and reflectance. So, as more and more networks use singlemode fiber, demand for fusion spliced termination options increases in kind.

Another key factor driving fusion splicing is the innovation and cost reductions that have resulted from competition between fusion splicer manufacturers. In the early days of fusion splicers, they resembled a suitcase rather than the compact, smart, technology-enabled products of today. The fusion splicer of yesteryear could often cost the same as a new car. Even as the capabilities and ease of use of the fusion splicer has increased, prices have decreased.

When certified optical fiber contractors were surveyed, the majority confirmed their utilization of cassette-based termination over other fusion spliced termination methods. The question becomes, what drives the preference for this winning technology?

Complexity Reduction

The pigtailed splice cassettes greatly reduce product complexity. The pigtailed splice cassette combines all the products required to terminate the optical fiber cable in a single part number. This one-part number includes an adapter panel, factory-polished preterminated pigtails (prestripped and routed within the splice tray). The splice tray itself is integrated into the cassette.

Even the consumables required to splice such items as transport tubing, tie-wraps for strain relief, and heat-shrink splice protectors are included. This reduces the complexity of specifying, ordering, and installation, allowing an optical fiber link to be built with three part numbers: the enclosure, pigtailed cassette, and cable.

In addition to complexity reduction, pigtailed splice cassettes require less labor to install. This is due in part to the “kitting” described earlier. However, another aspect of this labor reduction comes in the simplified routing enabled by the cassettes. In noncassette-based splicing, the fibers being terminated and the optical fiber pigtails are routed to splice trays that reside in a separate splice accessory in the same optical fiber enclosure or to a separate optical fiber splice enclosure mounted adjacent to the optical fiber patch panel. This requires the prerouting of both pigtails and field fibers to these separate splice areas before splicing can begin. With splice cassettes, the optical fibers being terminated are simply routed to the cassette and then splicing can begin. This can reduce installation time by up to 40%. Simplified routing and preparation not only save time but also avoid the possibility of damaged cable components due to improper routing or handling.

Despite the advances in field-installable connector technologies such as splice-on connectors and no-epoxy/no-polish connectors, each of these installation methods will have a small number of connectors that will not pass final certification testing with the first installation attempt. This is simply due to the conditions surrounding field installation such as installer proficiency, installation tools, or splice machine maintenance as well as cleanliness of the installation environment. Most connector types allow only one chance to install the connector properly; otherwise it is scrap. While low, this scrap rate is a well-known aspect of utilizing field installable connectors that contractors have accepted and build into their bidding and other business practices.

A key benefit of the splice cassette is that the termination process is the same regardless of connector type or fiber type and is nearly identical to the process to butt-splice optical fibers. Therefore, one training program can provide the capability to terminate or splice any fiber or connector type. Combined with the simplicity and ease of use built into modern optical fiber splice machines, this is complementary to establishing competency and capability of the fiber technician. Additionally, the use of pigtailed splice cassettes creates low-risk reaccess since the cassette is modular in groups of 12 or 24 fibers and protects the fiber and connectors inside of the cassette itself.

Another aspect that affects ease of installation is an appropriate enclosure in which to terminate. In the early days of cassette-based splicing, the focus was on rack-mounted enclosures since these enclosures represented most installations. As optical fiber drives deeper into the network approaching the network edge, Corning has met the demand by introducing wall-mounted enclosures, a single cassette enclosure and most recently NEMA-rated enclosures, all of which are fully compatible with the splice cassettes. Additionally, Corning has completed qualification of the CCH pigtailed cassettes to GR-3125, which allows the cassettes to be used in the appropriate NEMA-rated enclosures in the non-temperature-controlled outside plant environment.