Meeting Infrastructure Demands

The need for robust network infrastructure capable of supporting increasingly complex applications is fueling significant growth in IT spending on software and services. According to Gartner, worldwide spending on software is projected to increase 14 percent to US$1.23 billion in 2025, while IT services spending is expected to grow 9.4 percent to US$1.73 billion. This investment underscores the critical role of high-performance fiber optic cabling systems, a critical component of modern enterprise networks.

As the backbone of the network, these fiber cabling systems carry the bulk of the network traffic and provide connections within a single facility (intrabuilding) from the building entrance to equipment rooms, telecommunications rooms and telecommunication enclosures within enterprise networks. They may also extend between buildings on a campus or portfolio (interbuilding). Because of this central role, strong and precise fiber termination methods directly influence network reliability, signal quality, and overall system performance. Whether FM teams are accustomed to working with fiber networks or are newcomers to the field, understanding the nuances of termination techniques can significantly impact a project’s success. Recognizing the advantages and disadvantages of the typical field termination methods is essential for designing networks that meet the demands of a connected world.

Splicing and termination of fiber in the backbone is often required due to cable plant layout considerations, including cable length, bridge splices, and transition between non-listed and listed cable types at the building entrance point.

Choosing the right fiber termination method requires careful consideration of the unique factors specific to the installation environment. The following factors may influence the type of method and equipment used:

• Time and place: Evaluate how much time is available for installation and the type of installation environment where the work would take place. Also, identify the overall budget for material, labor and other factors.

• Installer expertise: Consider the contractor’s experience level and the required tools and consumables.

• System requirements: Identify current and future application and equipment interface requirements. How many fiber connections are there in the installation? Will there be moves, adds and changes? What is the level of optical performance or channel loss budget? What bulk fiber cable is being used: loose tube, tight buffered, ribbon or armored?

By carefully evaluating these factors, FMs can effectively select the most appropriate fiber termination option for their enterprise network.

Options for fiber termination in enterprise networks

Epoxy/polish connector

With field polishing terminations, contractors attach connectors to fibers using an adhesive and individually polish each connector. These connectors are the least expensive option. However, while once a very common method, epoxy/polish introduces many downsides. It can be time-consuming and requires consistent replenishment of consumables. Because this is craft sensitive, it is more difficult to provide a consistent end face quality.

Polishing an epoxy fiber SC connector

This polishing method can also be difficult to achieve lower insertion loss values, and the 55 dB return loss requirement for single-mode UPC connectivity. When an angled polish connector such as LC/APC or SC/APC is required, there are very few field polish options. If polishing is the selected method, investing in an optical time domain reflectometer (OTDR) to measure optical reflectance is recommended. While Tier 1 Certification (via an optical loss test set) may still be required when submitting for warranties, OTDR is often overlooked, leading to reflectance issues.

Mechanical splice connector

Traditionally, mechanical connectors were considered a temporary quick fix solution. However, the technology in mechanical connectors has advanced, and the advantages have made them a higher quality, long-term solution.

Splicing and terminating a mechanical fiber connector

With mechanical connectors, the connector end-faces are factory-polished and highly controlled, leading to better insertion loss, better return loss and less overall labor. However, this termination option will have higher material costs than field polished connectors and will require a precision cleaver.

Fusion splicing

Fusion splicing is becoming an increasingly popular fiber termination method, according to a recent poll conducted by Leviton Network Solutions. During a recent webinar, the poll found that a clear majority of participating network professionals—77 percent— are now using fusion splice pigtails, with 47 percent also using fusion splice-on connectors. This shift is further underscored by the comparatively low adoption of mechanical connectors (28 percent) and field polish connectors (8 percent). Unlike mechanical splicing that only aligns and does not physically join fibers, fusion splicing provides a permanent fusion connection between fibers. Fusion splicing typically has a loss of 0.1 dB or less, while mechanical splicing typically has higher insertion loss of between 0.2 dB to 0.75 dB.

Using a fusion splicer

While mechanical splices can be valuable for certain applications, fusion splicers can estimate the loss of the fusion splice, reducing the uncertainty of mechanical splicing or field polishing.

This advantage, coupled with the steady decrease of fusion splicer prices, has made splicing pigtails, splice-on connectors (SOCs) and splice modules become popular termination options. Pigtails, for instance, contain factory pre-polished connectors with a fiber stub that can be fusion spliced to the incoming fiber from a trunk cable. The splices are protected within a splice sleeve and stored in splice trays or modules along with any slack fiber. Similarly, SOCs include a factory pre-polished ferrule and a very short fiber stub that is housed within the protective sleeve of the connector.

Splice modules offer a highly efficient approach to installing and maintaining fusion splice connections. These modules integrate adapter bulkheads, pigtail assemblies, and splice holders, eliminating the need for individual splice trays while protecting spliced fibers and cable slack in an enclosure or panel.

Most high-quality fusion splicers are now computerized with a multitude of features that optimize the accuracy and speed of terminations. Mass fusion splicers are no exception, with many quality models boasting a splice time of 11 seconds and typical insertion loss of only 0.05 dB. Mass fusion splicing significantly increases productivity, especially for high-speed, high-density applications using MPO pigtails, as it allows splicing up to 12 fibers simultaneously, rather than individually.

Key considerations for choosing a termination method:

Loss performance

Excluding the epoxy connectors, all options use factory polished connectors for low insertion loss. Fusion splicing offers the added benefit of loss estimate, reducing the uncertainty associated with mechanical splicing or field polishing.

Planning and installation time

When factoring in the time available to complete a project, installers should account for preparation time alongside the total number of fibers to terminate. Mechanical splicing takes the shortest amount of time to terminate each fiber, but using splice modules can simplify projects by eliminating individual connector preparation and streamlining material handling.

Required fiber skill set

The installer’s overall experience with fiber termination and splicing can affect installation time and performance. Fusion splicing offers the added benefit of a faster learning curve.

Scrap & waste

Minimizing on-site waste is a growing priority on projects. With the ability for multiple re-terminations, splice modules cut waste compared to one-termination connectors. Consider splice modules with additional sustainability features. They help minimize waste with sustainable packaging and integrated shutters that eliminate dust plugs, which can add significant waste on large projects.

Equipment cost

Fusion splicing adds an initial investment in fusion splicing equipment. However, when working with loose tube or ribbon fiber cable, consider the additional cost of fan-out kits or other furcation methods required for routing fibers into buffer tubes for protection and preparing loose tube cables for direct termination.

Day 1 Cost (Material & labor)

While fusion splicers, SOCs, and splice modules involve higher initial material costs, the price of fusion splice equipment has been dropping in recent years as adoption has risen, creating a much stronger return on investment.

Day 2 (Moves, adds & changes)

When performing ongoing maintenance and updates, it is important to avoid disrupting adjacent fibers in the network. The modular design of splice modules allows for easy maintenance of individual spliced fiber and scaling up without impacting nearby fibers.

Proper cleaning practices

One of the most profound issues affecting fiber performance is cleanliness. Even a single particle of debris interfering with the fiber core of a connector can cause increased insertion loss or back reflection and even damage the connector or high-cost equipment.

Clean fiber is especially critical with single-mode fiber. While more dirt can collect on the multimode core, light can still pass through multimode’s larger 50 µm core size. With single-mode, one speck of dust can block all light. The size of a speck of dust in an office is 2.5 to 10 µm. A multimode fiber core is 50 µm or 62.5 µm, whereas a single-mode core is 8.2-8.6 µm. To put these into perspective, a single human hair ranges from 40 µm to 100 µm. This means that, in single mode fiber, data is transmitted through an area that is as little as one-tenth the thickness of a human hair. 

Dust in multimode & single-mode fiber

For technicians who are new to working with fiber, a video microscope is a great way to become familiar with what a clean or dirty fiber looks like. Be sure to inspect all connectors before installing and clean them if necessary. Then be sure to inspect them one more time after cleaning.

Pre-terminated options

Factory terminated cable assemblies are another option for higher-speed networks. Solutions with flexible MPO and LC connectors allow for gender and polarity changes in the field. If a project involves hundreds of fibers for either duplex or parallel applications, the reduced amount of time associated with pre-terminated cabling from project start to project completion can be an important benefit, as is the peace of mind that the assembly is delivered fully factory tested.

However, pre-terminated solutions are not always practical for enterprise networks, especially in installations where there are not set lengths for the cable run or there is the potential for numerous moves, adds and changes. One option that combines speed of deployment and performance assurance with greater flexibility is to use pre-terminated trunks on one end and an open blunt end on the other, allowing for field terminations at the edge.

Conclusion

With decreasing splicer prices and improved termination quality, fusion splicing has become the predominant method for terminating fiber cable. When choosing a termination method— whether fusion splicing, SOCs, pre-terminated assemblies or pigtails—carefully consider its impact on loss budget, installation time, and the project’s total installed cost. And as data rates continue to increase and consumers require more data and bandwidth in enterprise facilities, it is important to understand the health of existing fiber network infrastructure when deciding whether to reuse the infrastructure or upgrade to new infrastructure. Network contractors, consultants and cabling system providers are valuable assets in providing the right transceiver and cabling infrastructure based on the needs of the facility.