Optical cables consist of a core, cladding, coating, strengthening fibers, and an outer jacket, each serving a specific role in transmitting and protecting light signals.

Core

The core is the central part of the optical fiber that carries light signals encoded with data. It is typically made of high-purity glass (silicon dioxide) or plastic, allowing light to travel long distances with minimal loss. The core diameter varies depending on the fiber type: single-mode fibers usually have a core of about 9 microns, while multimode fibers range from 50 to 62.5 microns, affecting bandwidth and transmission distance .

Cladding

Surrounding the core is the cladding, which has a lower refractive index than the core. This difference enables total internal reflection, keeping light confined within the core and allowing efficient signal transmission over long distances .

Coating

The coating is a protective layer applied over the cladding. Usually made of plastic, it shields the fiber from physical damage, moisture, and stress during handling and installation. Coating thickness can range from 250 to 900 microns, providing mechanical support without affecting optical properties .

Strengthening Fibers

To enhance durability, optical cables include strengthening fibers made of materials like Kevlar®, fiberglass, or steel strands. These fibers absorb tension and prevent the core from breaking under pulling or bending forces, especially in outdoor or long-distance installations .

Outer Jacket

The outer jacket is the final protective layer, typically made of PVC, polyethylene, or other durable polymers. It protects the cable from environmental hazards such as abrasion, chemicals, and UV exposure. Jackets are often color-coded for identification, with orange being common for multimode fibers .

Summary

In essence, an optical cable is a carefully layered structure designed to transmit light efficiently while protecting the fragile glass or plastic fibers. The core carries the light, the cladding confines it, the coating protects it, the strengthening fibers provide mechanical support, and the outer jacket shields the entire assembly from environmental damage .