What Are Fiber Optic Cables Made Of

The composition of a fiber optic cable primarily consists of a fiber core, cladding, buffer layer, strength members, and an outer jacket; each component utilizes specific materials and serves a distinct function.

Fiber Core: Composed of ultra-high-purity silicon dioxide (SiO₂)-with a purity level reaching 99.9999%-to ensure the efficient transmission of optical signals. The diameter of the fiber core typically ranges from 9 to 125 micrometers, and its surface roughness is controlled at the atomic level to minimize signal loss.

Cladding: Encasing the optical fiber core, it is typically composed of glass doped with germanium or fluorine; its refractive index is slightly lower than that of the core, thereby facilitating total internal reflection and confining the optical signal within the core for transmission.

Buffer Layer: Typically made of acrylic resin or other elastic materials, with a thickness of approximately 250 micrometers, it serves to absorb mechanical stress and protect the optical fiber from physical damage.

Reinforcement Elements: Utilize aramid fibers (Kevlar) or steel strands to provide additional mechanical strength, enabling the optical cable to withstand tensile forces of up to 80 kilograms.

Outer Jacket: Depending on the specific application scenario, the material of the outer jacket varies:

Polyethylene (PE): Used in outdoor environments; offers excellent UV resistance and weatherability, with a service life exceeding 25 years.
Low Smoke Zero Halogen (LSZH): Used in enclosed spaces such as subways and tunnels; generates minimal smoke and toxic gases when burned.
Polyvinyl Chloride (PVC): Used in indoor environments; offers good flexibility, making it easy to bend and install.