Fiber Optics Terminology

Fiber Optics Terminology

Commonly used fiber optics terms and their definitions

• Analog – Pertaining to a class of devices or circuits in which the inputs and/or outputs can be one of infinitely many values
• Attenuation – Loss of signal intensity as the signal propagates through a medium.
• Bare fiber – A fiber consisting of only the core and cladding. Without a jacket, bare fiber is more vulnerable to damage from handling and other forces.
• Cable – A fiber complete with core, cladding, and protective jacket, and possibly additional protective layers.
• Core – The central region of an optical fiber through which light is transmitted. It has a higher refractive index than the cladding that surrounds it.
• Cladding – The material surrounding the core of an optical fiber. It has a lower refractive index than the core to prevent light from refracting through it, keeping it inside the core.
• Digital – Pertaining to a class of devices or circuits in which the output varies in discrete steps, such as pulses or “on” and “off” states.
• Duplex – Two-way communication, where both sides can transmit and receive information. A duplex fiber optic cable contains two parallel fibers, carrying information in opposite directions.
• Fiber – A thin filament of glass or plastic consisting of a core and cladding.
• Graded Index – Refractive index profile where the fiber’s core’s refractive index varies with radial distance from the core’s center. Light is guided by the fiber’s gradient refractive index rather than reflected at the interface between the core and cladding. This allows a bandwidth up to three time that of step index POF.

  

• Jacket – The outermost layer of a fiber optic cable which protects the fiber from damage. Jackets are typically made of plastic, but other materials may be used.
• Mode – A single ray of light that is transmitted through a medium.
• Numerical Aperture – The sine of the fiber’s critical angle. Fiber with a larger numerical aperture requires less precision to splice and align than fiber with a smaller numerical aperture.
• Prefluorinated Fiber – A type of graded index plastic optical fiber (GI-POF) capable of high-speed data transmission, and is simple to install and terminate.
• Simplex – One-way communication, where one side transmits information, and the other side receives it. Simplex fiber optic cable contains a single fiber, which carries information in one direction.
• Step Index – A refractive index profile where the fiber core’s refractive index is constant across the cross-section of its core.

  

• Termination – Process of cutting, finishing, and securing a connector onto the end of a fiber or cable with minimal attenuation. This is normally accomplished using a razor cutter, polishing paper, or a hot plate to melt the end of the fiber.