The difference between single mode fiber and multimode fiber

single mode fiber

Single-mode fiber has a very small core diameter that allows only one mode of light to pass through (hence single-mode). The number of reflections caused by light propagating along the core is greatly reduced. This in turn reduces attenuation and allows the signal to travel faster and farther. Think of it as a thin hose with a lot of water flowing, for example, it will be compressed more, travel faster and farther through the thin hose than through the larger one.

Single-mode fiber can usually be identified by its standard yellow jacket, usually denoted 9/125, which means a core diameter of 9µm (micrometers) and a cladding diameter of 125µm.

multimode fiber

Multimode fiber has a larger diameter core that allows multiple modes of light to propagate, simple? As you can imagine, more data can be transferred due to the larger core diameter. However, more light refraction and attenuation occurs. This means they typically travel shorter distances than single-mode fiber due to signal attenuation. They are most commonly found in networks for short-range data applications, such as LANs (Local Area Networks).

multimode fiber

Multimode fiber is commonly referred to as 50/125 and 62.5/125. This is the core to cladding ratio for 50µm to 125µm and 62.5µm to 125µm.