Different types of fiber have various limitations and features. The features depend on the speed and the maximum distance that the fiber can operate optimally. The characteristics of a fiber determine the application in which the fiber cable is most appropriate.

Multimode Fibers

The multimode fiber also called the multimode step-index fiber to contain a big diameter than the single mode fibers. The diameters of the core are from 100um to 970um.

Characteristics of a Multimode Fiber

  • Have a large core diameter
  • Available in glass, plastic-clad silica or plastic fibers cladding.
  • The most popular
  • Carry signals for moderate distances, but optical amplifiers boost the signals and make it possible to use the cable over long distances.
  • They experience high attenuation than single mode fibers. The rate of attenuation is directly proportional to the distance covered by the cables.
  • The color of the outer jacket maybe orange or aqua.
  • Use LEDs the light emitting diodes
  • The multimode fiber cable has a high light gathering capacity due to the large numerical aperture and the large core.

Their Bandwidth Often Classifies the Multimode Fibers Into:

  1. OM1- 300meters with a core diameter of 850nm
  2. OM2- 600 meters with a core diameter of 1310nm
  3. OM3- 1000 meters with a core diameter of 850nm
  4. OM4- 1040 meters with a core diameter of 850nm


The different classes have different transmission rate, transceiver type, and different link length. The 850nm Ethernet cable supports link lengths of up to 200 meters. The 850nm operating is the most popular due to the low-cost lasers such as vertical cavity surface emitting lasers (VCSELs). VCSELS allows the users to increase the data rates at a lower cost than other lasers.

The large core diameter of the multimode fibers simplifies connections and makes it possible for the cable to connect to LED and VCSEL lasers. The multimode fiber cable has a high light gathering capacity due to the large numerical aperture and the large core.

 Single-Mode Fibers

Single mode step-index fibers have a tiny core, and its construction and operation are straightforward. The cables come in different colors due to the jacket made of polymer to protect the core. The color of the jacket is essential for color-coding purposes.

The Characteristics Include:

  • More costly than multimode fibers due to the expensive electronics required in the network.
  • Used in the most application, not due to its affordability but rather its quality and reliability.
  • Very small core diameters, 5 to 9.5um and an outside jacket of 125um surround the core.
  • Ability to carry a signal over very long distances, unlike the multimode fibers.
  • They have low attenuation thus widely used in the communication industry.
  • The propagating modes depend on the wavelength of the light being carried. As the wavelength increases, the modes decreases progressively to single mode.
  • The color is often yellow.
  • Has a large bandwidth
  • Recommended for high precision research due to its ability to be reduced into a single mode.

The OS1 and OS2 Fibers

The single mode fibers are divided into two standards: OS1 AND OS2 fibers. OS stands for Optical Single-mode fiber. The OS1 is the oldest standard with a maximum link of 10km. The standard was developed at a time the demand for internet connectivity was low. Currently, 10km can no longer satisfy the needs of the customer. OS2 was thus designed to cover much greater distances than 10km and is widely deployed in the telecommunication industry. The OS1 fiber is an indoor fiber while the OS2 is an outdoor fiber.

As an end-user, it is crucial to identify the right type of fiber based on your application.


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