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Industry Insights

Connecting the DOTS - Connecting with Fiber Optic Splicing Systems

Thursday, January 10, 2019 | by Rudy Montgelas

CTD with Rudy Monteglas - Banner


Why splice two hair-thin pieces of glass?

Optical fiber splicing has traditionally been the best way to permanently connect two optical fiber cables.  Due to a fiber’s extremely tiny core it is important to have a low-loss, precise and reliable splicing system to maintain the splice’s mechanical and optical integrity.

Fiber optic outside plant applications, such as long-haul telephony and cable TV, have traditionally employed two preferred methods of splicing two optical fibers together in the field: mechanical and arc-fusion splicing. In addition, an encapsulant-filled splice enclosure, or splice case, where the fiber slack and splices are often stored protects the splices from moisture and mechanical damage.  You may have seen some of these splice cases up on telephone wires or poles around your neighborhood.

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Mechanical splices are available in many shapes and sizes, but they all have the same things in common:
  • There’s a mechanical element of the splice, such as a V-groove, that provides precise alignment of the two fibersCTD Image 2
  • There’s an index-matching adhesive, or gel, that eliminates the light path air-gap reflections
  • The fibers must be captivated by the splice and mechanically stable over a wide temperature range
  • The splice must be able to protect the fibers from damage due to compression and bending or separation due to tensile forces.

Arc-fusion splicing uses a controlled high voltage arc to precisely melt the two glass fibers together.  Why is interest in arc-fusion splicing growing?  It’s because it’s the best way to assure a permanent, low loss and stable fiber connection.
Arc fusion splicers used to be costly, bulky units that had microscopes for fiber alignment by eye, and required accurate manual micrometer screw adjustments before “striking the arc” to fuse the two fibers together. An initial, short duration, pre-fuse arc also helped to clean off debris and contamination.
CTD - Image 3

The technology of arc-fusion splicing has come a long way in taking the guesswork out of the process.  Arc-fusion splicers are much more compact and do not require alignment by eye. Microprocessor-based arc control and imaging techniques, combined with motorized stages, automatically and precisely align the two fibers, as well as performing final tensile proof-tests and splice loss estimations.

The importance of fiber cleanliness and good cleaves

Fiber cleanliness, good cleaves and accurate control of the arc parameters such as power, arc duration and fiber feed is required to obtain a low-loss splice with little or no mechanical defects or bubbles in the glass. 

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 For both mechanical and fusion, fibers must be cleaned and cleaved properly before splicing. Dirt and debris, as well as poor fiber cleaves, yields poor splices.  A fiber’s coating must be stripped avoiding nicks and cleaned properly with a fiber splice cleaner that leaves no residue. Typical cleave angles from a precision cleave tool should be less than 0.5 degrees, especially for single mode fibers.  Shooting the fiber splice with a visible light source (VFL), at the end, is a good way to check its optical integrity.

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What’s Legrand’s Infinium splice cassette all about?

Legrand has many flexible solutions for splicing optical fibers and for storing fiber slack when needed. Pigtail splicing with splice trays has been a popular way to splice optical fibers at the rear of fiber enclosure. Fiber bend-limiters and storage spools provide storage for buffered-fiber slack.
Still, the fragility of 250-micron acrylate-coated fiber fusion splices can make splicing a challenge.  Legrand’s new Infinium splice cassettes combine individual or 12-fiber ribbon splices with fiber slack storage all within the same M4 and M2 footprint as a standard LC to MPO fan-out cassette.
Introducing the Infinium splice cassettes with: CTD Image 6
  • Front/rear fiber enclosure loading capability
  • A compact modular design
  • Clear removable protective cover
  • Removable splice organizer with buffer storage
  • Factory cleaves
  • Single fiber and 12-fiber ribbon splices
  • 30% Labor Savings
So, how do I find out more about Legrand’s Infinium Splice Solutions?

Contact your nearest Legrand distributor or visit our website

From the CTD team: We hope you have enjoyed all our CTDs in 2018.  We’re looking forward to more of them for you this year.

References and further reading
1 Mechanical Splices, The Fiber Optic Association, Inc (FOA):
2 Optical Fiber Fusion Splicing, Photo of defects in the glass fiber after fusion splicing: Toolboom:
3 Photo of MiniMod miniature automatic handheld fusion splicer: Aurora Optics, Optical