The outer sheath color of an optical fiber cable indicates its type: single-mode cables are typically yellow, multimode cables are orange or aqua, and outdoor or hybrid cables are often black.

Standard Outer Jacket Colors

The TIA-598-C standard defines the outer jacket colors to help technicians quickly identify fiber types:

• Single-mode fibers (OS1/OS2): Yellow jacket, used for long-distance or high-speed networks .
• Multimode fibers:
  • OM1 and OM2: Orange jacket, designed for LED light sources and legacy networks .
  • OM3 and OM4: Aqua jacket, optimized for laser-based high-speed networks (10G, 40G, 100G) over short distances . OM4 may also appear in violet (Erika Violet) depending on the manufacturer .
• OM5 fibers: Lime green jacket, supporting wideband multimode applications .

Special Cases

• Outdoor cables: Typically black to resist UV exposure, regardless of fiber type .
• Hybrid or composite cables: May use black jackets or custom colors, often with printed legends to indicate fiber types inside .
• Custom or in-building cables: Manufacturers can produce jackets in any RAL color if clearly labeled with fiber classification .

Summary

The outer sheath color is the fastest visual cue for identifying fiber type and application. While yellow, orange, and aqua are standard for single-mode and multimode fibers, black or custom colors are used for outdoor, hybrid, or specialized installations. For multi-fiber cables containing different fiber types, printed legends on the jacket provide precise identification .