Fibre Optic Cable

An optical fiber cable, also known as fiber optic cable, is an assembly similar to an electrical cable, but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed. Different types of cable are used for different applications, for example long distance telecommunication, or providing a high-speed data connection between different parts of a building.

Fiber optic cabling is based on optical fibers, which are long, flexible, hair-width strands of ultra-pure glass. Optical fibers are formed when preform blanks - portions of specially manufactured glass - are heated to between 3,000o and 4,000o and then drawn out at a rate of up to 66 feet per second. As optical fiber is pulled, it is constantly monitored by a laser micrometer, which ensures that its diameter is perfectly uniform from start to finish.


In order for optical fibers to transmit data over long distances, they need to be highly reflective. On their way to being spooled, newly-pulled glass fibers pass through coating cups and ultraviolet ovens, which respectively apply and then cure the thin plastic buffer coating that creates a mirror effect within the fiber.

The finished optical fiber is then extensively tested in a wide range of categories, including Tensile Strength, Refractive Index Profile, Fiber Geometry, Attenuation, Bandwidth, Chromatic Dispersion, Operating Temperature, Temperature Dependence of Attenuation, and Ability to Conduct Light Underwater. After testing has proven that the newly-manufactured optical fiber meets all standards, it is sold for use in fiber optic cabling.

Depending on what type of application it will be used for and how much data it will need to transmit, fiber optic cable can be built around a single strand of optical fiber, or larger groupings of it. To assemble a complete fiber optic cable, the strand or cluster of optical fiber is placed at the core, to be surrounded by a loose tube of PVC, which leaves the fiber room to bend when being routed around corners and through conduit. The loose PVC is then covered with a layer of shock-absorbing aramid yarn - usually made of Kevlar. To top it all off, the cable receives a final outer-jacket coating of PVC, which helps to seal out moisture.

In order for the finished cable to transmit data signals, it needs to be connected to the two other main components of a fiber-optic system. The first of these is the optical transmitter, a device which converts electrical and analog signals into either On-Off or Linear modulating light signals, then releases that data into the fiber optic cable. The cable then relays the data emitted by the optical transmitter to the optical receiver, which accepts the light signal and reformats the data into its original form.

Fiber optic cabling has advantages over standard copper coaxial cables, in that it can transmit larger quantities of data with far less loss, is able to maintain signals over long distances, carries little risk of corrosion, and is virtually free from interference. To view a wide array of fiber optic cables and accessories that can take your telecommunications network to a whole new level.

How fiber optics works
Fiber optics transmits data in the form of light particles -- or photons -- that pulse through a fiber optic cable. The glass fiber core and the cladding each have a different refractive index that bends incoming light at a certain angle. When light signals are sent through the fiber optic cable, they reflect off the core and cladding in a series of zig-zag bounces, adhering to a process called total internal reflection. The light signals do not travel at the speed of light because of the denser glass layers, instead traveling about 30% slower than the speed of light. To renew, or boost, the signal throughout its journey, fiber optics transmission sometimes requires repeaters at distant intervals to regenerate the optical signal by converting it to an electrical signal, processing that electrical signal and retransmitting the optical signal.

Types of fiber optic cables
Multimode fiber and single-mode fiber are the two primary types of fiber optic cable. Single-mode fiber is used for longer distances due to the smaller diameter of the glass fiber core, which lessens the possibility for attenuation -- the reduction in signal strength. The smaller opening isolates the light into a single beam, which offers a more direct route and allows the signal to travel a longer distance. Single-mode fiber also has a considerably higher bandwidth than multimode fiber. The light source used for single-mode fiber is typically a laser. Single-mode fiber is usually more expensive because it requires precise calculations to produce the laser light in a smaller opening.

Multimode fiber is used for shorter distances because the larger core opening allows light signals to bounce and reflect more along the way. The larger diameter permits multiple light pulses to be sent through the cable at one time, which results in more data transmission. This also means that there is more possibility for signal loss, reduction or interference, however. Multimode fiber optics typically use an LED to create the light pulse.

While copper wire cables were the traditional choice for telecommunication, networking and cable connections for years, fiber optics has become a common alternative. Most telephone company long-distance lines are now made of fiber optic cables. Optical fiber carries more information than conventional copper wire, due to its higher bandwidth and faster speeds. Because glass does not conduct electricity, fiber optics is not subject to electromagnetic interference and signal losses are minimized.

In addition, fiber optic cables can be submerged in water and are used in more at-risk environments like undersea cable. Fiber optic cables are also stronger, thinner and lighter than copper wire cables and do not need to be maintained or replaced as frequently. Copper wire is often cheaper than fiber optics, however, and is already installed in many areas where fiber optic cable hasn't been deployed. Glass fiber also requires more protection within an outer cable than copper, and installing new cabling is labor-intensive, as it typically is with any cable installation.

  • OFC: Optical fiber, conductive
  • OFN: Optical fiber, nonconductive
  • OFCG: Optical fiber, conductive, general use
  • OFNG: Optical fiber, nonconductive, general use
  • OFCP: Optical fiber, conductive, plenum
  • OFNP: Optical fiber, nonconductive, plenum
  • OFCR: Optical fiber, conductive, riser
  • OFNR: Optical fiber, nonconductive, riser
  • OPGW: Optical fiber composite overhead ground wire
  • ADSS: All-Dielectric Self-Supporting
  • OSP: Fiber optic cable, outside plant
  • MDU: Fiber optics cable, multiple dwelling unit

Fiber optics uses
Computer networking is a common fiber optics use case, due to optical fiber's ability to transmit data and provide high bandwidth. Similarly, fiber optics is frequently used in broadcasting and electronics to provide better connections and performance.

Military and space industries also make use of optical fiber as means of communication and signal transfer, in addition to its ability to provide temperature sensing. Fiber optic cables can be beneficial due to their lighter weight and smaller size.

Fiber optics is frequently used in a variety of medical instruments to provide precise illumination. It also increasingly enables biomedical sensors that aid in minimally invasive medical procedures. Because optical fiber is not subject to electromagnetic interference, it is ideal for various tests like MRI scans. Other medical applications for fiber optics include X-ray imaging, endoscopy, light therapy and surgical microscopy.