In the designation 62.5/125 fiber, what does "62.5" refer to?

The designation "62.5/125" refers to specific dimensions of the optical fiber being described. The "62.5" indicates the core size of the fiber, measured in microns. This means that the diameter of the light-conducting core of the fiber is 62.5 microns.

In multimode fiber optics, core size is crucial as it affects the amount of light that can be transmitted and the types of light sources that can be used. A core size of 62.5 microns is standard for multimode fibers, allowing for the propagation of multiple light modes, which is essential for certain networking applications.

The second number, "125," represents the diameter of the cladding surrounding the core, which is always larger than the core itself. Cladding serves to reflect light back into the core and maintain the transmission of light through total internal reflection. Thus, understanding the core size is key to knowing the performance characteristics of that specific type of fiber.