Physics – 3.2.2 Refraction of light | e-Consult

An optical fibre cable consists of several key components:

• Core: The core is the central part of the fibre, made of glass or plastic, through which the light signal travels. It has a higher refractive index than the cladding.
• Cladding: The cladding is a layer of glass or plastic surrounding the core. It has a lower refractive index than the core. The cladding ensures that light is confined to the core through TIR.
• Buffer Coating: A plastic coating that protects the core and cladding from damage.
• Strength Members: These provide mechanical strength to the cable, protecting the fibre from stress and strain.
• Outer Jacket: The outermost layer, providing further protection against environmental factors like moisture and abrasion.

Types of Optical Fibre:

• Single-mode fibre: Has a small core diameter (around 8-10 micrometers). It allows only one mode of light to travel through it. This results in less modal dispersion (spreading of the light pulse) and allows for longer distances and higher bandwidth. Typically used for long-distance telecommunications.
• Multi-mode fibre: Has a larger core diameter (typically 50 or 62.5 micrometers). It allows multiple modes of light to travel through it. This results in more modal dispersion, limiting the distance and bandwidth compared to single-mode fibre. Typically used for shorter distances, such as within a building or campus network.

Table summarizing the differences: