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Fiber Optic Color Coding
Last Updated: 01/31/2017


Fiber optic cable is available with a variety of performance capabilities for a variety of applications. This makes interoperability between these options an issue to consider before installation. As an aid to help installers match up compatible products the industry has standardized on specific colors to indicate a fiber optic component’s performance characteristics. The two components where this is applies are cable and connectivity (connectors, coupler ports, adapters, etc.).


Multi-mode (OM1/2, OM3/4, OM4+) fiber has a core size of 50 microns or 62.5 microns and is used for shorter cable lengths. The large cores allow multiple beams to travel down the core. It is typically used as a backbone for general data and voice applications between floors and close buildings on campus.

Single-mode(OS1/2) is used for long cable lengths. The smaller core uses a single beam that follows the core, thus being faster and brighter and provides higher bandwidth. Typically used for extreme long distances, high speed, telco backbones, CATV networks, etc.

Installation Considerations:

Mixing of OM3, OM4 and/or OM4+ will result in performance that meets only the lowest performing type used. For consistent performance all components should be the same.

Some fiber optic cables will include different types within the same jacket making the jacket color neutral regarding performance. Refer to print legend on jacket to identify fiber classifications.

Do not interconnect PC, UPC and/or APC connectors. Doing so will result in high return loss and damaged connectors.

Common Options:

Blue jacketed cable is sometimes used to designate a specialty polarization-maintaining fiber optic cable. Black jacketed cable is sometimes seen in UV resistant, outdoor rated cable.

Popular Manufacturers(Cable):

Popular Manufacturers(Connectivity):

Related Industry Terms/Acronyms:

  • Meter – fiber optic distances are typically expressed in meters. 1 one meter is equal to 3.28 feet (39.37 inches).

  • OFNP (Optical Fiber Nonconductive Plenum) - designates a fiber optic cable suitable for installation in a plenum.

  • OFNR (Optical Fiber Nonconductive Riser) - designates a fiber optic cable suitable for a riser installation.

  • Wavelength - the distance from one energy wave to another. Fiber optic cable uses longer wavelengths in the infrared to minimize attenuation.

  • Bandwidth - refers to the range of signal frequencies within which a fiber optic channel will operate.

  • Nanometer - equal to 1 billionth of 1 meter. It is used in fiber optics to express the wavelength of transmitted light.

  • OSP - Outside Plant cable is designed for use in an outdoor environment and suitable for direct burial, aerial, or underground conduit applications.

  • Attenuation - loss of signal over the length of a network link.

  • Insertion Loss – signal loss due to the insertion of an additional component or the creation of a splice within a continuous path.

  • Bend Radius – the minimum radius a cable can be bent without kinking it, damaging it or shortening its life. When cabling is bent beyond the specified minimum it can cause transmission failures.

  • PC (Physical Contact) - fiber optic connector with typical return loss of <-25db.

  • UPC (Ultra Physical Contact) - fiber optic connector finely polished with slight curvature in endface and typical return loss of <-50db.

  • APC (Angled Physical Contact) - single-mode fiber optic connector with endface polished to an 8 degree angle; typical return loss of <-60db.

  • Laser-Optimized - a characteristic of multi-mode OM3, OM4 and OM4+ fiber optics which uses laser instead of LED as a light source, thus achieving higher transmission rates than OM1/2.

  • VCSEL (Vertical Cavity Surface Emitting Laser) - high speed laser light source used with laser-optimized multi-mode fiber.

Comparison Chart:

Cable Jacket

Color: Mode: Core Size:
Yellow Single-mode OS2 8.3 micron
Orange Multi-Mode OM1/OM2 62.5 / 50 micron
Aqua Multi-Mode OM3/OM4 50 micron
Violet Multi-Mode OM4+ 50 micron

*Note: yellow may also indicate single-mode OS1, though this is obsolete and fully compatible with OS2.
*Note: these color designations are typical, but exceptions exist.

  • OS1/2


  • Multi-Mode OM1/2


  • Multi-Mode OM3/4


  • OM4+



Color: Mode:
Blue Single-mode OS2
Green(APC) Single-mode OS2
Beige Multi-Mode OM1
Black Multi-Mode OM2
Aqua Multi-Mode OM3/OM4
Violet Multi-Mode OM4+

*Note: these color designations are typical, but exceptions exist.

  • OS2


  • OS2 APC

    OS2 APC

  • OM1


  • OM2


  • OM3/4


  • OM4+


See Also:

Further References:

  • FOA (The Fiber Optic Association)
  • BICSI (Building Industry Consulting Services International)
  • IEEE (Institute of Electrical and Electronics Engineers, Inc.)
  • ISO (International Organization for Standardization)
  • TIA (Telecommunications Industry Association)
  • ANSI (American National Standards Institute)


Why do I see single-mode OS2 described with a 9 micron core size?

OS2 (and the obsolete OS1) has a core size of 8.3 microns, but many sources will simply round up that number to 9 microns in their descriptions. It is the same cable whether described as 8.3 or 9 micron.

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