Multi-core optical fibers can be spliced ​​using cold joints

Multi-core optical fibers can be spliced using cold (mechanical) joints, but achieving low-loss, high-quality connections is more challenging than with fusion splicing.

Cold Splicing Overview

Cold splicing, also known as mechanical splicing, involves aligning fiber endfaces precisely and holding them in place using a mechanical fixture, often with a V-groove and index-matching gel or adhesive to reduce optical loss . This method does not melt the fiber ends, making it faster and simpler than fusion splicing, and it is commonly used for temporary connections or field installations where fusion equipment is unavailable .

Challenges with Multi-Core Fibers

Splicing multi-core fibers introduces additional complexity:

• Precise alignment: Each core must be aligned individually to ensure minimal insertion loss. Misalignment of even one core can significantly degrade performance .
• Uniform contact: Mechanical cold splices rely on physical contact and gel, which may not provide uniform optical coupling across all cores, especially in tightly packed multi-core fibers .
• Limited performance: Cold splices generally have higher insertion loss and lower return loss compared to fusion splices, which can be critical in high-bandwidth or long-distance applications .

Practical Considerations

• Cold splicing is feasible for low-power, short-distance, or temporary multi-core fiber connections, such as FTTH deployments or quick field repairs .
• For high-performance or permanent installations, fusion splicing is preferred because it provides lower loss, higher reliability, and better long-term stability .
• Specialized holders or V-groove arrays can help align multiple cores simultaneously, but achieving the same precision as fusion splicing remains difficult .

Conclusion

While multi-core fibers can be cold-spliced, the method is generally limited to applications where convenience and speed outweigh the need for minimal optical loss. For critical or high-bandwidth systems, fusion splicing remains the recommended approach due to its superior alignment precision and optical performance. Cold splicing is most effective for temporary connections, field repairs, or low-power multi-core fiber applications .