Method for Termination and Splicing of 72-Core Optical Cable

A 72-core optical cable is typically terminated using MTP/MPO connectors for high-density connections and fusion splicing for permanent joints, ensuring low insertion loss and high reliability.

Overview

Terminating and splicing a 72-core optical cable requires careful handling due to the high fiber count. The cable is usually ribbon fiber, where multiple fibers are aligned in flat ribbons, making it suitable for MTP/MPO multi-fiber connectors or fusion splicing to pigtails or patch panels . Proper termination ensures minimal insertion loss (≤0.3 dB per connector) and low reflectance, critical for high-speed networks like 40/100G Ethernet or DWDM systems .

Termination Methods

1. MTP/MPO Connectors
   • Designed for 12, 24, or 72 fibers in a single connector array.
   • Pre-terminated cables or field-installable MTP/MPO connectors are used for high-density applications.
   • Fibers are cleaved and aligned in the connector ferrule; index-matching gel may be used in some pre-polished connectors .
   • Ideal for data centers and high-density patch panels.
2. Field Polishing / Pre-Polished Connectors
   • Field polishing involves epoxy-and-polish techniques for each fiber, but for 72-core cables, this is labor-intensive.
   • Pre-polished connectors allow the fiber to butt against a pre-polished stub, reducing field polishing time and maintaining low insertion loss .

Splicing Methods

1. Fusion Splicing
   • Preferred for permanent joints in singlemode or multimode fibers.
   • Uses an electric arc to melt and fuse fiber ends, producing a continuous glass joint with insertion loss typically 0.01–0.1 dB .
   • Ribbon fibers can be mass fusion spliced, aligning multiple fibers simultaneously, which is efficient for 72-core cables.
   • Steps:
     1. Strip the outer jacket and buffer coatings carefully.
     2. Clean fibers with lint-free wipes and high-purity alcohol.
     3. Cleave fibers precisely using a high-quality cleaver.
     4. Align fibers in the fusion splicer and perform the arc fusion.
     5. Protect the splice with heat-shrink sleeves or splice trays.
2. Mechanical Splicing
   • Fibers are held in alignment using a mechanical fixture with index-matching gel.
   • Suitable for temporary repairs or multimode fibers where slightly higher insertion loss is acceptable.
   • Less common for 72-core cables due to complexity and higher loss compared to fusion splicing .

Best Practices

• Cleanliness: Over 70% of fiber network issues are caused by contamination. Inspect and clean all fibers before termination or splicing .
• Inspection: Use a fiber inspection microscope or video scope to check end-face quality and alignment.
• Splice Trays: Organize and protect splices in trays to prevent micro-bends and mechanical stress.
• Testing: Measure insertion loss and return loss after termination or splicing to ensure compliance with standards (IEC 61300, ITU-T G.652.D), .

Summary

For a 72-core optical cable:

• Use MTP/MPO connectors for high-density terminations.
• Fusion splicing is the preferred method for permanent joints, especially with ribbon fibers.
• Mechanical splicing is reserved for temporary or emergency connections.
• Maintain cleanliness, precise cleaving, and proper protection to ensure low-loss, high-reliability optical performance .