Colors of Multimode and Singlemode Fibers

Singlemode fiber typically has a yellow jacket, while multimode fiber jackets are orange, aqua, or lime green depending on the type.

Singlemode Fiber Color

Singlemode fiber (SMF) is designed for long-distance transmission and carries a single light mode. It is commonly identified by a yellow outer jacket. Singlemode fibers are often labeled as OS1 or OS2, and the core diameter is very small, around 8–10 µm, which allows minimal light reflection and low attenuation over long distances.

Multimode Fiber Color

Multimode fiber (MMF) supports multiple light modes and is used for shorter distances, such as within buildings or data centers. The jacket color varies by type: OM1 and OM2: Orange jacket, core diameters of 62. 5 µm (OM1) or 50 µm (OM2), suitable for 100 Mbps to 10 Gbps applications.

OM3 and OM4: Aqua jacket, 50 µm core, laser-optimized for higher bandwidths and speeds up to 100 Gb/s. OM5: Lime green jacket, wideband multimode fiber supporting multiple wavelengths for very high-speed data transfer.

Quick Identification Tips

Jacket color is the fastest visual cue: yellow for singlemode, orange/aqua/lime green for multimode. Printed labels on the cable, such as “OS2 9/125” for singlemode or “OM3 50/125” for multimode, provide confirmation. Core size can also help: singlemode cores are ~9 µm, while multimode cores are 50–62.

5 µm. By checking both the jacket color and labeling, installers can quickly distinguish between singlemode and multimode fibers, ensuring proper network performance and compatibility.