What Are the Different Types of Fiber Optic Cables?by Ma Wen Jie
Fiber optic cable and fiber optic data transmission technology revolutionized data transfer in the late 20th century. By encoding data as pulses of light, rather than pulses of electricity, data densities on fiber optic cables far exceeded their copper counterparts. The data is sent, literally, at light-speed over fiber optic cables.
Regardless of the type of fiber, the overall process for making optical fibers is similar. Two layers of glass, or plastic in the case of plastic fiber, are melted together. The two pieces of glass are drawn out into a long fiber with a core and an external sheathing. Differences in the refractive indexes of the core and sheath are what allows light to travel through the core while being contained within that core by the sheath. The thin optical fibers are drawn down, cooled and spooled for bundling and manufacturing of multi-strand fiber optic cables.
Single-mode fibers have a narrower core and allow for one data stream, or mode, to be transmitted over very long distances. Single mode fiber carries far more bandwidth, but in a narrower spectral width, than multi-mode fiber.
Multi-mode fiber strands use a much thicker core than single mode. Multi-mode fiber can carry data encoded using multiple light sources, thus allowing for multiple data streams to travel over a single optical fiber. The downside of multi-mode is transmission distance and available data bandwidth. Multi-mode transmission is good over shorter distances and can not support the high bandwidth of single-mode fibers.
Plastic optical fiber (POF) is usually not used for data transmission. Plastic fiber optic cables do not have the optical purity required for reliable data transmission. POF is usually used for decorative and aesthetic transmission of light. Examples of this are toys where light is transmitted through the fibers creating beautiful, colorful clumps of optical fibers. An added advantage of POF over glass fiber in entertainment or aesthetic situations is durability and cost. POF is much cheaper to manufacture than glass fiber and is not as fragile.
The Future of Fiber Optic Cable
Current research into future fiber optic cable technology will allow tunable cables similar to a radio. Data streams on a single mode fiber will be able to be contained within a particular light spectrum and will be tunable similar to a present-day radio.
- Photo: Crystal Woroniuk, stock.xchng