Complete Guide to Optical Cable Numbering and Classification

Optical cables are classified by mode, core size, performance, and color-coded standards, including OM1–OM5 for multimode and OS1–OS2 for single-mode fibers.

Multimode Fiber Classifications (OM Series)

• OM1: 62.5/125 µm core/cladding, suitable for short-distance applications, typically up to 300 meters at 1 Gbps .
• OM2: 50/125 µm core/cladding, supports higher bandwidth than OM1, commonly used for 1–10 Gbps over moderate distances .
• OM3: 50/125 µm laser-optimized multimode fiber, designed for 10 Gbps up to 300 meters and 40/100 Gbps up to 100 meters .
• OM4: Enhanced 50/125 µm multimode fiber, supports 10 Gbps up to 550 meters and 40/100 Gbps up to 150 meters .
• OM5: Wideband multimode fiber, optimized for multiple wavelengths (850–950 nm), enabling shortwave wavelength division multiplexing (SWDM) for high-speed data centers .

Single-Mode Fiber Classifications (OS Series)

• OS1: Indoor single-mode fiber, typically tight-buffered, optimized for up to 2 km in optical loss-limited applications .
• OS2: Outdoor single-mode fiber, optimized for long-distance transmission, low attenuation, suitable for distances exceeding 10 km .

Core Sizes

• Single-mode fiber: 8–9 µm core diameter, carries a single light mode, minimizing dispersion for long-distance transmission .
• Multimode fiber: 50 µm or 62.5 µm core diameter, supports multiple light modes, ideal for shorter distances .

Fiber Jacket Types

• PVC: Standard indoor jacket, cost-effective, flexible .
• Plenum (CMP): Fire-resistant, low smoke, suitable for air-handling spaces .
• Tactical/Ruggedized: Heavy-duty, often with Kevlar reinforcement, for outdoor or portable applications .

EIA/TIA-598-D Color Coding

• Outer Jacket Color: Indicates fiber type (e.g., OM1–OM5, OS2) for quick identification .
• Inner Fiber Sequence: Each fiber in multi-fiber cables follows a 12-color repeating pattern (Blue, Orange, Green, Brown, Slate, White, Red, Black, Yellow, Violet, Rose, Aqua) for identification .
• Connector/Boot Color: Identifies polish type and fiber mode (UPC/APC, single-mode/multimode) to ensure proper mating and performance .

Summary

Optical cable numbering classifications combine fiber mode (single vs. multimode), core size, performance rating (OM/OS series), and standardized color codes to ensure proper selection, installation, and maintenance. Following these standards allows technicians to reliably identify fibers, manage high-density cabling, and maintain network performance across diverse applications .