How to polish an MPO jumper wire in fiber optic cable polishing

Polishing an MPO jumper wire involves a multi-step process using specialized fixtures, lapping films, and careful inspection to achieve a smooth, defect-free fiber end face for optimal optical performance.

Equipment and Materials Needed

• Polishing Machine: Automated or manual machine capable of controlling pressure and speed for MPO connectors .
• MPO Polishing Fixture (Puck): Holds multiple fibers at the correct angle (typically 0° for UPC or 8° for APC) during polishing .
• Polishing Films: Sequence of lapping films from coarse to fine grit (e.g., Silicon Carbide SC15B → SC3D → SC1A → CE0.5C) or diamond films for high precision .
• Polishing Pads: Hard (glass) and soft (rubber/PU) pads to control fiber height and curvature .
• Cleaning Supplies: Distilled water, 99% isopropyl alcohol (IPA), lint-free wipes, and compressed air .
• Inspection Tools: Fiber inspection microscope and interferometer to check end-face geometry, fiber height, and surface quality .

Step-by-Step Polishing Procedure

1. Preparation and Cleaning
   • Clean the MPO connector, ferrule, and work surface to remove dust and debris.
   • Secure the connector in the MPO polishing fixture.
   • Apply deionized (DI) water to the polishing film and connector for lubrication .
2. Rough Polishing (Epoxy Removal)
   • Use coarse lapping film (e.g., SC15B, 30 µm Silicon Carbide) to remove excess epoxy and shape the ferrule surface.
   • Apply moderate, even pressure in a figure-eight motion to avoid uneven removal .
3. Intermediate Polishing (Surface Refinement)
   • Replace coarse film with finer grit (e.g., SC3D, 3 µm) to smooth the fiber ends.
   • Reduce pressure slightly and continue polishing to remove scratches from the rough stage .
4. Fiber Height Adjustment
   • Use specialized fine film (e.g., SC1A) to adjust fiber protrusion and ensure uniform height across all fibers.
   • Lightly polish to achieve precise physical contact and alignment .
5. Final Polishing (Mirror Finish)
   • Use ultra-fine film (e.g., CE0.5C or silicon dioxide final polishing sheets) to achieve a scratch-free, mirror-like finish.
   • Apply very light pressure and DI water to prevent undercutting or fiber damage .
6. Cleaning Between Steps
   • Thoroughly clean the connector and fixture after each stage using DI water, IPA, and compressed air to prevent cross-contamination .
7. Inspection and Testing
   • Inspect the fiber end-face under a microscope for scratches, chips, or debris.
   • Measure end-face geometry (radius of curvature, apex offset, fiber height) with an interferometer to meet standards like IEC 61300-3-35 and Telecordia GR-326 .
   • Conduct Tier 1 testing (insertion loss and return loss) using an optical loss test set (OLTS) to verify optical performance .

Tips for Optimal Results

• Always follow the sequence from coarse to fine films to prevent surface defects.
• Maintain consistent pressure and motion to avoid uneven polishing.
• Use DI water as a lubricant to reduce heat and prevent scratches.
• Regularly inspect and replace polishing films to maintain quality. By carefully following these steps, you can achieve high-quality, low-loss MPO jumper connections suitable for high-speed fiber optic networks .