Core diameter refers to the central part of an optical fiber through which light is transmitted. In optical fiber terminology, the fiber is generally composed of a core, which is surrounded by a cladding, and then often a buffer or protective jacket outside the cladding.
The diameter of the core determines how many different paths (or modes) the light can take through the fiber. Based on this, optical fibers are classified into:
Single-mode Fibers (SMF):
- Core Diameter: Typically around 8 to 10 micrometers (μm).
- Carries a single ray of light, usually directly down the middle.
- Suited for long-distance transmission due to minimal signal attenuation and no modal dispersion.
Multi-mode Fibers (MMF):
- Core Diameter: Typically between 50 and 62.5 micrometers (μm).
- Allows multiple rays or modes of light to travel through the core simultaneously.
- Suited for shorter distances compared to SMF due to modal dispersion, where different modes arrive at the receiver at slightly different times.
The core diameter is a crucial parameter in fiber optic communications as it affects the fiber’s data carrying capacity, modal dispersion, and operational wavelength, among other characteristics. The choice between using SMF or MMF largely depends on the application’s distance and bandwidth requirements.