How to use filler material for 12-core optical cables

Filler materials in 12-core optical cables are applied to fill voids, block water, and provide mechanical buffering to protect the fibers and ensure stable signal transmission.

Types of Filler Materials

Fiber Gel: A high-purity, semi-transparent gel that comes into direct contact with the optical fibers inside loose tubes. It provides mechanical cushioning, reduces microbending stress, and prevents hydrogen-induced signal attenuation. Fiber gel must be extremely clean, low-stress, and chemically stable to avoid long-term damage to the fiber coating.

Cable Jelly: Used to fill core gaps, stranded structure voids, or outer layers of the cable. It does not contact the fibers directly but provides overall water-blocking and structural support. Cable jelly is less stringent in optical-grade requirements but must maintain long-term stability and water resistance.

Water-

Blocking Materials: Active water-blocking compounds, such as water-swellable yarns, tapes, or gels, expand upon contact with water to prevent longitudinal water migration along the cable core.

Application Steps

Preparation: Ensure the cable tubes and cores are clean and free of debris. Select the appropriate filler material based on whether it will contact the fiber (fiber gel) or fill structural voids (cable jelly). Filling Loose Tubes: Inject fiber gel into each loose tube containing the optical fibers.

The gel should fully coat the fibers, forming a flexible support layer that disperses mechanical stress during bending, tension, or vibration. Filling Core Gaps and Stranded Voids: Apply cable jelly to the interstitial spaces between loose tubes, around strength members, and in the outer layers of the cable. This ensures complete water-blocking and structural integrity.

Water-

Blocking Integration: If using active water-blocking materials, place water-swellable yarns or tapes along the cable core or around the tubes. These materials will expand if water penetrates, providing an additional barrier. Inspection and Sealing: After filling, inspect the cable to ensure all voids are filled and no air pockets remain.

Seal the cable ends to prevent contamination and maintain the integrity of the filler material.

Best Practices

Use high-purity, low-stress gels for direct fiber contact to prevent microbending and signal loss. Avoid overfilling, which can cause excessive pressure on fibers and deformation of the cable structure. Ensure compatibility of filler materials with the cable sheath and tube materials (PVC, nylon, polyethylene, etc.),.

Maintain proper temperature control during filling to prevent degradation of the gel or jelly. By following these steps, the 12-core optical cable will have enhanced water resistance, mechanical protection, and long-term transmission stability, ensuring reliable performance in various environmental conditions.