What Is Fiber Optic Cable Made Of?

Optical fiber cables are a popular choice for high-speed and long-distance data tranSMission. They are thin, flexible, and capable of high-quality transmissions. Smaller fiber optic patch cables also add flexibility to servers and data centers. If you find yourself wondering what fiber optic cable is made of, you are not alone. Here’s what you need to know.

Basic components of a fiber optic cable include the core, cladding, a buffer, and a jacket. Each one has a unique set of properties that dictate what materials fiber optic cables are made of.

Fiber Optic Cores

The core is the heart of optical fiber cables, no matter their size.  It is the main component that transmits data as light signals. The core, made from hair-thin strands of glass or plastic fiber, has a high refractive value.

Glass cores consist of ultra-pure glass, typically made from silica. It is readily available and provides good optical transmission at various wavelengths. A standard glass core diameter is between 50 and 125 microns, although they can be larger.

Plastic optical fibers can be made from several different plastic polymers, including polymethylmethacrylate, polystyrene, and polycarbonate. PMMA is the most common type of plastic used to create plastic optical fibers. Plastic cores are substantially larger at around 1000 microns, although they can vary from 750 to 2000 microns.

Cladding

The cladding, made from similar materials to the core, reflects light back into the core to confine light to the core. It generally has a lower refractive value to maximize the core’s performance. Because of this, the materials used are sometimes of a lower quality with slightly more impurities than the core. Cladding thickness is usually between 125 and 630 microns.

Buffer

The cladding is surrounded by another layer of material called the buffer. This is substantially thicker than the other two layers and provides physical protection for the inner materials. Acrylate, a type of plastic, is a common buffer material. Silicone and polymers are also popular. Depending on the type of fiber cable and its intended use, additional materials may be added for rigidity. These materials are covered by another outer buffer. Stiffeners such as fiberglass strands can help add shape and some rigidity to fiber optic cables.

Many fiber optic cables use Kevlar to add strength and durability. Cables with Kevlar have higher tensile strength than those without it. It is often combined with resin to create Kevlar® Reinforced Plastic for applications requiring compression, flexibility, and a low cable diameter.

Jacket

An outer jacket covers the fiber optic cable buffer. The jacket provides a final layer of protection. Common jacket materials include polyethylene, polyvinyl chloride, low-smoke zero halogen, Plenum, and Riser. Depending on the exact configuration, there may be hundreds or thousands of fibers in a single cable wrapped together with a durable exterior layer.