Low-density materials commonly used in optical fiber cables include fiberglass-reinforced plastics (G-FRP), aramid yarn, polybutyleneterephthalate (PBT), polypropylene (PP), and high-density polyethylene (HDPE), which provide strength while minimizing weight.

Core and Cladding

The optical fibers themselves are made from ultra-pure silica (SiO₂), often doped with germanium to control the refractive index. While silica is dense, the surrounding coatings and protective layers are designed to reduce overall cable weight .

Strength Members

To maintain mechanical integrity without adding excessive weight, optical cables use dielectric strength members such as:

• Fiberglass-reinforced plastic (G-FRP): Provides high tensile strength with low density .
• Aramid yarn (PPTA, e.g., Kevlar): Offers excellent tensile modulus (≥120 GPa) and low weight, making it ideal for central or stranded strength members .

Tube and Filler Materials

• Polybutyleneterephthalate (PBT): Used for loose tubes, it is lightweight, durable, and resistant to environmental stress .
• Polypropylene (PP): Often used as fillers to maintain cable geometry while keeping density low .

Outer Jackets

• High-density polyethylene (HDPE): Commonly used for outer jackets, HDPE is lightweight, UV-resistant, and mechanically robust, providing protection without significantly increasing cable weight .
• Low-smoke zero-halogen (LSZH) compounds: Used in environments requiring fire safety, these materials are also relatively low in density.

Additional Considerations

• Water-blocking elements: Polyester filaments or super-absorbent polymers are used to prevent moisture ingress while adding minimal weight .
• Blowable microcables: For microduct installations, low-density sheaths improve blowability and reduce friction during installation .

Summary

For optical fiber cables, low-density materials are selected to balance mechanical strength, environmental resistance, and ease of installation. Key materials include G-FRP, aramid yarn, PBT, PP, and HDPE, which together ensure the cable is lightweight yet durable, suitable for aerial, duct, or microcable applications .