Fiber Optic SC Connector and Propagation Modes

What is an optical fiber connector?

An optical fiber connector is a mechanical device that is attached to the end of an optical fiber cable, and allows for quicker connection and disconnection than splicing. These devices mechanically couple and align the fibers to allow light to pass through effectively. In addition, a connector physically marks the area where signal power can be lost in the premises.

What is an SC connector?

The SC in its name stands for “subscriber connector”, which is a multi-purpose push/pull style connector with a locking tab developed by NTT. These connectors are often used for newer network applications that utilize single-mode and multimode fiber optic cables. It provides for accurate alignment through its ceramic ferrules. Common matched SC connectors are rated with 1000 mating cycles with an insertion loss of 0.25 dB.

What is mode of propagation?

There are generally two propagation modes for fiber optic cables, namely single-mode and multimode. Each mode functions differently in terms of attenuation and time dispersion. These can be further subdivided into multimode step index, single-mode step index, single-mode dual-step index, and multimode graded index. The type of mode exhibited by a fiber optic cable depends on the cable dimension and the indices of refraction.

  1. Multimode Step Index
  2. A fiber optic cable that demonstrates multimode propagation with step index profile is distinguished by greater time dispersion and higher attenuation. It is the least expensive amongst the propagation modes and predominantly used in premises environment. This type of cable is most ideal for linked lengths of over 5 kilometers, and can be made out of glass, plastic, or PCS. A typical cable’s MMF core diameter is set at 50 or 62.5m.

  3. Single-Mode Step Index
  4. A fiber optic cable that exhibits single-mode propagation with a step index profile is distinguished by minimum time dispersion and attenuation. As it is the most expensive type of cable that is used in premises environment, it is most often used with metropolitan- and wide-area networks. Local area networks have also been using single mode fiber optic cables with a step index profile since it has been continuously extending over greater distances.

    Its typical core diameter is set at an exceedingly small range of 8 microns to 10 microns, whilst its standard cladding diameter is set at 125 microns. This type of cable is often made out of silica glass.

  5. Single-Mode Dual-Step Index
  6. Fiber optic cables that exhibit single-mode propagation with a refractive index called dual-step index is characterized by extremely low macrobending losses, two zero-dispersion points, and a lower dispersion over a wider wavelength range. It is set with dual clad fiber, which is also known as depressed-clad fiber.

  7. Multimode Graded Index
  8. Fiber optic cables demonstrating a multimode propagation with a refractive index profile known as graded index is distinguished by levels of attenuation and minimum time dispersion. Fibers in this cable have a higher refractive index in the core that gradually decreases as it extends outward from the cylindrical axis. The core and the cladding are treated as a single graded unit.

    The cost of multimode cables with a graded index is between that of the other cables that exhibit the other propagation modes. They usually have core diameter set at 50, 62.5, and 85 microns, whilst its cladding diameter is often at 125 microns. This type of fiber optic cable is often used in premise data communication.

For more information on SC Connector read:

  • SC Connector
  • SC Connector