Cable Designs for Fiber Optic Networks

By: CableOrganizer®

fiber optic

There are different basic cable designs used when designing a fiber optic network. Each depends on the environments where these networks are located. Among them are:


Loose tube cables are made up of numerous fibers inside a small plastic tube that are coiled around a central strength member, then covered with a protective outer jacket. This provides protection against damage and moisture. This cable design is often used in outside and long-distance applications, because they can maintain a more stable transmission, even when under continuous mechanical stress. Loose tube cables can be strung overhead, buried directly into the ground, and used in conduits. That’s because they are designed to endure harsh outdoor temperatures, have high tensile strength, and have a large bend radius and diameter. The fibers must be handled carefully and protected to prevent damage since they have only a thin buffer coating. Without interfering with other protected buffer tubes that are being routed to different locations, the buffer-tube design of the loose tube cable allows easy drop-off of groups of fibers at intermediate points. The loose tube cable design is also helpful in the administration and identification of fibers in the system. Loose-buffered cables are available in all-dielectric construction, armored construction, and riser-rated constructions.


Even though some tight-buffered cable designs are for outdoors, most of them are for indoor applications and shorter distances. These individual fibers are coated with a buffer coating like soft plastic, and then are bundled together with a single outer jacket. The tight-buffered design is very flexible. It has low crush and impact resistance along with a low attenuation change at lower temperatures. The tight-buffered design is well-suited for "jumper cables" that connect outside plant cables to terminal equipment, and for linking various devices in a premises network. The breakout design and distribution design are the two typical constructions of the tight-buffered cables. The breakout design has an individual jacket for each tight-buffered fiber, and the distribution design has a single jacket protecting all the tight-buffered fibers.


When creating an assembly in high-density applications, such as data centers, this is where ribbon cables are used. They are comprised of multiple fibers arranged in a parallel lineup, and bonded together to create a flat, ribbon-style structure. This type of a layout is ideal for places where space may be reduced, with this type of cable useful in high-speed transmission and high bandwidth applications. These assemblies are designed with maximum fiber density, to contain 12 or 24 fibers. There may, however, be variations that have higher fiber counts. The cables often have a supplemental protective layer, like a ribbon matrix or ribbon gel, a substance that blocks moisture from entering the fibers, providing mechanical and environmental protections.


When one cable is comprised of multiple cables covered by one jacket — such as a fiber optic and copper cable — it is known as a composite cable. The cable may include a loose tube cable, tight buffered cable or ribbon cable, paired with a pair of twisted pair copper conductors. Its outer jacket may provide mechanical protection, shielding against environmental factors, plus insulation between the different cable elements. This type of cable is used for power or communications. This is a viable option when one is looking to limit the number of separate cables used in an application, with one composite cable carrying both data and power cables within one jacket, such as a Power over Ethernet (PoE) application. This type of cable design may be found in telecommunications networks, security systems, industrial environments, and smart buildings.


This type of assembly combines a layer of metal or fiber strands with the cable, to provide further protection. The armor makes this variety of fiber optic cable suitable for harsh environments, where cables may be subject to rodents, crushing, and bending. The structure of the assemblies may include loose tubes, tight buffered fibers or ribbon cables, paired with the armor layer. There are different types of armor that could be used, either metal like steel or aluminum, or fiber strand armor. Rather than a metal, this type of armor implements fiber strands, such as aramid fibers like Kevlar®. Though the cables are fortified, they remain flexible, which helps them be easily installed and routed.

Shop at CableOrganizer® for fiber optic supplies, including fiber optic cables, fiber optic connectors, termination kits, enclosures, patch panels, and more.

Related Items