White Paper Selecting the Correct Fusion Splicer for Your Application By: Keith Foord, Product Manager, Greenlee Communications

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1 White Paper Selecting the Correct Fusion Splicer for Your Application By: Keith Foord, Product Manager, Greenlee Communications Introduction There are many variables to consider when selecting the correct fusion splicer for a fiber optic installation project. The wrong decision can cause delays in getting the job done on time and within budget. Therefore, it is important to select the splicing technology which addresses the appropriate variables for optimum results. There are currently three fusion splicing technologies to consider; Core Alignment, Active Clad and V-groove, each have advantages and disadvantages which will be discussed in this White Paper. First, we will begin by reviewing best practices for successful splicing that apply to all technologies. Typical Causes of High Fusion Splice Losses Splicer Contamination Keeping the fusion splicer clean is of paramount importance for successful fusion splicing. If the V- Grooves are dirty or the cladding of the fiber isn t fully cleaned, the fiber will not rest in the proper position for alignment to the fiber in the adjacent V-groove. If the fiber or the splicer is contaminated with dust or dirt, the resulting splice will be subject to higher losses or even splicing failure. It is impossible to eliminate all dirt and dust where splicing is performed but the technician has a responsibility to clean and care for the splicer as recommended by the manufacturer. Following recommended cleaning will yield lower splice losses and increase the lifetime of the splicer. Non-Concentric core Dirt in V-Groove V-Groove Misalignment Should the V-Grooves become damaged (chipped or scored) over the course of time due to use, improper cleaning or neglect, the relative alignment of the V-Grooves may become compromised and higher splice losses will occur. Fiber Concentricity & Ovality

2 Fibers installed more than 15 years ago had poor geometries and are especially problematic when splicing to similar fiber and when splicing to the new G.652 single mode fiber (SMF). Single mode fiber has a core diameter nominally of nine microns. However, if the fiber core is not in the geometric center of the cladding, the mechanical alignment of the cladding (in V-Grooves) will not optimally align the cores in the X and Y dimensions which will result in high splice losses. Similarly, the ovality of fiber can also cause losses. There is no provision to match oval profiles of two fibers being spliced. If one fiber is oval and the other fiber is round the result will be measurable loss and possible reflection. These problems are further compounded when fibers from different manufacturers are spliced together since the geometries may be slightly different. Cladding Diameter Tolerance When splicing dissimilar fibers, or fibers from two different manufacturers, the actual diameter of the fiber claddings may also be dissimilar. The smaller diameter fiber will sit slightly lower in the V- Groove than the opposite fiber resulting in further misalignment and therefore higher splice losses. Courtesy: Corning Inc Fusion Spicing Technologies Core Alignment Core alignment fusion splicers offer the most capable and tolerant splicing technology that is commonly available. The major advantages of core alignment are the low splice loss when splicing dissimilar fibers and the ability to precisely align two fibers when splicing under adverse conditions. The universal splice loss measurement is defined by cutting a near symmetrical fiber in half and splicing the two halves back together. This standard measurement provides a baseline; however, it does not emulate the real-world conditions of a technician. Core Alignment fusion splicers employ a Core Detection System (CDS). With CDS, light is shone into the fiber allowing embedded cameras to identify the fiber core. This is achieved by detecting the difference in the refraction of light at the core/cladding interface. Core alignment splicer s use six motors and two cameras to align the fibers in the X, Y and Z dimensions. When the fibers are dissimilar the core alignment splicer will precisely align the two fibers by identifying the center of each fiber core prior to fusing. Any misalignment of the fibers within the two V-Grooves due to fiber tolerances, fiber geometries, contamination or damage to the V-Grooves is compensated for resulting in repeatable, low loss splicing. The 910FS Core Alignment Splicer from Greenlee Communications routinely successfully splices under adverse conditions and will yield a typical 0.02dB insertion loss for standard G.652 single mode fiber. Although the 910FS can overcome imperfect splicing conditions, technicians must still be diligent in performing recommended cleaning and handling best practices.

3 Core alignment splicers are ideal for splicing G.651 multimode fibers because they compensate for variations in core diameters that would otherwise lead to splice losses. Even though the cores are nominally 50 microns they may be slightly different. Compounding the issue of splicing multimode fiber is that the composition (dopants) of two fibers may be slightly different which may require the technician to adjust the electrode power applied to each fiber. This is conventionally done by adjusting the fiber position with respect to the electrodes thus controlling the ARC power to each fiber. Core Alignment Motor Control (Six Motors) Clad Alignment (V-Groove) Clad Alignment, or V-Groove splicers, are typically the most cost effective; however, there are many compromises that may reduce the effectiveness of this technology in the real world. Cladding Alignment splicers uses only two motors and rely on the perfect alignment of the two V-Grooves. The concentricity of the outside of the fiber cladding must be aligned perfectly with the core of the fiber to accurately align in the X and Y axes before the motors bring the fibers together in the Z axis for splicing. Typical splice loss for a V-Groove fusion splicer is specified to be typically 0.05dB for G.652, standard single mode fiber, rather than the 0.02dB loss for the 910FS Core Alignment fusion splicer. Although not a large difference this specification is met under ideal and new, out of the box conditions and is degraded with contamination and regular wear and tear on the V-Grooves. Not cleaning or improper cleaning techniques will cause excessive splice losses when compared to more capable splicing technologies such as the Core and Active Alignment splicers.

4 V-Groove Motor Control (Two Motors) Typical causes of high splice losses that are accentuated in V-Groove splicers include issues with fiber geometry such as diameter mismatch, concentricity of core to clad, and V-Groove contamination and/or damage due to improper cleaning. Because legacy fiber often suffers from geometric inconsistencies, V-groove splicers should not be used when splicing to legacy fiber. Active Clad Alignment Active Clad fusion splicers provide near Core Alignment splicing performance at a more costeffective price point when splicing the single mode fibers available today. The geometries of the fibers produced in the last decade have improved consistency, and allow for this less complicated splicing technology even amongst various manufacturers. The 915FS Active Clad splicer from Greenlee Communications utilizes four motors to align the fiber without the two focus motors which are found on the objective lenses of Core Alignment splicers. This is possible because the center of the fiber core is precisely located with respect to the clad of the fiber, thus we can rely on the X and Y stages to accurately align the fibers, minimizing the splice loss. Again, the splicing technician must be diligent and properly clean the splicer V-Grooves to maintain the integrity of the alignment to maintain this performance. Active Clad Motor Control (Four Motors)

5 Measuring the Completed Fusion Splice All makes and models of fusion splicers display an estimated splice loss which needs to be verified with an OTDR. The estimated loss measurement is a combination of the cleave quality, axial alignment of the two fibers and the shape of the completed splice. The 930XC OTDR by Greenlee Communications measures insertion loss and return loss and should be used to verify the splice quality. The SOR file can then be download so a full report can be saved for proof of compliance and historical documentation. The splice shown has an insertion loss of 0.048dB and no reflectivity. Recommendations The following table gives the basic recommendation for selecting the appropriate fusion splicer/technology for various applications. Application Splicing Technology Greenlee Communications Splicer FTT(x) (New Fiber) Active Clad 915FS

6 Old Fiber to New Fiber Core Alignment 910FS Dissimilar Fiber Core Alignment 910FS New Fiber to New Fiber Active Clad 915FS Network Backbone Core Alignment 910FS Summary The Greenlee Communications 910FS Core Alignment fusion splicer provides the splicing technician the most robust, lowest loss splicing technology that is commercially available. With six motors, the 910FS can precisely locate and align the two cores of the two fibers under the most adverse conditions. The 915FS Active Clad fusion splicer will provide Core Alignment performance when splicing fibers of like geometries. Because fibers produced in the past decade have similar geometries, the 915FS does not need to find the center of the core of the fiber when splicing. This eliminates the need for the objective lens focus motors which helps reduce the cost of the splicer. Clad splicers are prone to high splice loss due to their inability to compensate for fiber geometry issues and are extremely sensitive to V-Groove and fiber contamination. Although they are the most cost effective splicing technology, the technician should consider the more capable 915FS Active Clad splicer for best performance.