Optical fiber splicing sequence

Optical fiber splicing involves preparing, aligning, joining, and protecting fiber ends using either fusion or mechanical splicing techniques.

1. Fiber Preparation

The first step in both fusion and mechanical splicing is to strip the fiber of its protective coatings, jackets, tubes, and strength members, leaving only the bare fiber core visible. After stripping, the fiber must be cleaned thoroughly using 99.9% isopropyl alcohol and lint-free wipes to remove any contaminants that could affect light transmission or alignment .

2. Fiber Cleaving

Next, the fiber ends are cleaved using a precision fiber cleaver. This creates a flat, perpendicular end face on each fiber, which is critical for minimizing splice loss. In fusion splicing, the cleave must be highly accurate, while mechanical splicing allows slightly less precision .

3. Fiber Alignment

• Fusion Splicing: The stripped and cleaved fibers are placed in a fusion splicer, which aligns the fibers using either core alignment (camera-based) or cladding alignment (V-groove-based). Core alignment is preferred for single-mode fibers to achieve minimal insertion loss .
• Mechanical Splicing: The fibers are inserted into a mechanical splice unit, which holds the fibers in precise contact. An index-matching gel or epoxy is used to facilitate light transmission across the joint .

4. Fiber Joining

• Fusion Splicing: The aligned fibers are fused together using an electric arc, creating a permanent, continuous connection with very low insertion loss (typically 0.1 dB or less), .
• Mechanical Splicing: No heat is used; the fibers are held in place mechanically, and the index-matching gel ensures light passes efficiently. Typical insertion loss is around 0.2–0.3 dB .

5. Splice Protection

After joining, the splice must be protected from mechanical stress and environmental factors. This is done using splice trays, closures, shrink tubing, or silicone gel, which prevent bending, tensile stress, and moisture damage . Mechanical splices often include a built-in protective shell, while fusion splices require additional protection.

Summary

• Fusion splicing is ideal for permanent, high-reliability connections with minimal loss, suitable for long-haul and high-bandwidth networks.
• Mechanical splicing is faster, easier, and suitable for temporary or field repairs, though it has slightly higher insertion loss. By following these steps carefully, technicians can ensure low-loss, reliable optical fiber connections that maintain signal integrity across network installations .