The main materials of optical fiber cables

Optical fiber cables are primarily made of glass or plastic cores, surrounded by cladding, protective coatings, and outer jackets to ensure signal integrity and durability.

Core

The core is the central part of the fiber through which light travels. It is typically made from ultra-pure silica glass (SiO₂) for high-performance telecommunications, or sometimes from plastic for shorter-distance applications. The core may be doped with materials like germanium or phosphorus to slightly increase the refractive index, which helps control light propagation and minimize signal loss .

Cladding

Surrounding the core is the cladding, usually made from fluoride-doped silica or other doped glass. The cladding has a lower refractive index than the core, which ensures total internal reflection, keeping the light confined within the core . In plastic fibers, the cladding may also be made from a different type of polymer.

Coatings and Buffers

To protect the delicate core and cladding, optical fibers are coated with dual-layer UV-cured acrylate or polyimide. The primary coating is soft to absorb mechanical stress, while the secondary coating is harder for additional protection. Around the coated fiber, a buffer layer made of acrylate or other plastics provides further mechanical protection and facilitates handling during installation .

Strength Members

Fiber optic cables often include strength members such as aramid yarn (e.g., Kevlar), fiberglass rods, or steel wires to prevent stretching and provide tensile strength, especially in outdoor or aerial installations .

Outer Jacket

The outer jacket protects the cable from environmental hazards like moisture, UV exposure, and physical damage. Common materials include HDPE (high-density polyethylene), LSZH (low-smoke zero-halogen) compounds, or other specialized polymers depending on the application .

Additional Materials

Some cables may include water-blocking gels or powders, metallic components for grounding, or ribbon matrices for multi-fiber arrangements. Color inks are often applied for fiber identification . In summary, the main materials of optical fiber cables are glass or plastic for the core, doped glass or polymer for the cladding, acrylate or polyimide coatings, strength members like aramid yarn, and protective outer jackets, with additional materials added for specific environmental or functional requirements .