Cracking the Code: Colors and Meanings in Optical Fiber Communication

Optical FiberColor-coding is an integral part of the fiber-optic industry as it helps to differentiate cables, fibers and connectors with different modes and performance levels. Apart from reference and identification, color-coding also has much to do with the environment where the cables will be installed.

Types of Optic Fiber Cables

Unlike the wire-based system of copper wire communication, fiber-optics is a chain of coded light pulses that then processes and translates information from the transmitter. Fiber-optics use light pulses to transmit information down the fiber lines instead of using electronic pulses down copper lines.

A LED or injection-laser diode (ILD) generates the light pulses, which then travels into the fiber-optic medium down a cable.

There are three types of fiber optic cables commonly used – single mode, multimode and plastic optical fiber or POF. A single-mode cable is usually used for longer distances while the multimode is for shorter distances. Plastic optical fiber is for longer-wavelength infrared applications.

Cracking the Color Code

Manufacturers, such as OptDex, use color codes to distinguish cables from each other. Cables may have different hues across manufacturers, but most colors have the same meaning. There may also be color additions in small parts such as the leaver or frame of an adapter.

The color coding helps installers indicate the correct port for a patchcord. Here are standard meanings for indoor cable, jacket and connector boot colors.

Indoor Cable or Jacket Colors

  • Orange – multi-mode optical fiber
  • Aqua – OM3 or OM4 gig laser-optimized 50/125 micrometer multi-mode optical fiber
  • Violet – OM 4 multi-mode optical fiber
  • Grey – outdated color code for multi-mode optical fiber
  • Yellow – single-mode optical fiber
  • Blue – sometimes used to designate polarization-maintaining optical fiber
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Connector Boot Colors

  • Blue – physical contact (PC); mostly used for single mode fibers, some manufacturers use this for polarization-maintaining optical fiber
  • Green – angle polished (APC)
  • Black – physical contact (PC); used for both multimode and singlemode cables designed for outdoor use to protect cable from solar and UV light exposure
  • Grey or Beige – physical contact; multimode fiber conncetors
  • White – physical contact (PC)
  • Red – high optical power; sometimes used to connect external pump lasers or Raman pumps.

Color hues may sometimes vary depending on the material used and the manufacturing process for the cable’s insulation. Manufacturing process may alter the hue of the colors, but nevertheless, these have been the standards since the 1980s. Manufacturers may also deviate from the standards if a client requests it.