Fiber Optic Cable Fusion Splicer Coating

Fiber optic cable coatings protect the glass core and cladding, typically measuring 250µm for single-mode fibers, and must be carefully stripped and handled for high-quality fusion splicing.Coating Overview

Fiber optic cables consist of a core, cladding, and a protective coating. The coating shields the fragile glass core and cladding from mechanical stress, moisture, and contamination, ensuring signal integrity during installation and operation . For single-mode fibers, the coating is usually 250 microns thick, surrounding a 125-micron cladding and an 8-micron core . Multimode fibers may have slightly thicker coatings, and some specialty fibers, like polarization-maintaining or multi-core fibers, may require customized coatings .

Stripping and Preparation

Before fusion splicing, the coating must be carefully stripped without damaging the glass core. Recommended practices include:

• Using precision fiber strippers calibrated for the coating diameter (250µm for single-mode, 900µm for coated fibers) to avoid microfractures .
• Applying controlled, uniform pressure to prevent bending or twisting, which can create invisible cracks that degrade splice quality .
• Stripping a length of 10–20 mm, depending on the splicer and fiber type .
• Cleaning the exposed fiber with lint-free wipes and 99%+ isopropyl alcohol, moving from the coating edge to the cleave tip in a single stroke to avoid redepositing contaminants .

Handling During Fusion Splicing

Once stripped, the fiber coating plays a role in alignment and tension control:

• Fibers are placed in the V-grooves of the splicer, aligning the cores while maintaining proper tension to prevent microbends or breakage .
• Some fusion splicers, like Fujikura or Sumitomo models, automatically detect and align fibers, but cleaning the V-grooves is essential to prevent misalignment from dust .
• The coating also helps stabilize the fiber during the fusion arc, ensuring a low-loss, permanent splice .

Specialty Considerations

For specialty fibers (thin-diameter, large-diameter, multi-core, or PANDA fibers), the coating may differ in thickness or material, requiring specific splicing parameters and tools . Using manufacturer-recommended consumables, such as splice sleeves, ensures long-term reliability and minimizes failure rates .

Summary

The fiber coating is critical in fusion splicing, providing mechanical protection, aiding in alignment, and ensuring splice quality. Proper stripping, cleaning, and handling of the coating are essential to achieve low-loss, high-reliability splices in both standard and specialty fiber applications .