Fiber Types

Optical fibers, with the exception of some types of communication fiber, are all composed of two distinct and different types of optically conducting material. For simplicity, the term glass will be used for all types of fiber. The center, or CORE of the fiber is the portion that actually carries light and is the glass with the higher index of refraction. A thin layer of glass with a lower index of refraction, called the CLAD, surrounds the core and is fused to it, creating a totally reflecting barrier at the interface of the glasses.

A typical glass fiber for most light carrying applications will be in the range of .001 to .003 inches (25-75 microns) in diameter. It will have 83% of its area composed of core and 17% of the area will be clad.


Optical fibers are commonly produced from glass, plastic and synthetically fused silica, often called silica or quartz fiber. Each type has its own advantages and drawbacks. For data communication applications, silica fiber is the overwhelming choice. For illumination and sensing applications, glass fiber is the better choice for cost and NA reasons, while plastic excels for ease of assembly in applications that do not require operating temperatures above 175 degrees F. (70°C).

Sometimes it's important to know how many fibers there are in a bundle diameter.

Use our fiber count calculator.

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