Color of the ring on the optical module

The color of the ring on an optical module indicates its operating wavelength, with common colors including black (850nm), blue (1310nm), purple (1490nm), and yellow/green (1550nm).Standard Pull Ring Colors by Wavelength850nm (Multimode Fiber, Short Distance) – Black ring, typically used for short-range transmissions up to 550 meters .1310nm (Single-Mode Fiber, Medium Distance) – Blue ring, suitable for distances up to 10 km .1490nm (BiDi or GPON/FTTx Applications) – Purple ring, often used in bidirectional modules .1550nm (Long-Distance Single-Mode Fiber) – Yellow or green ring, used for distances up to 80 km or more .CWDM and BiDi ModulesCWDM Modules: Use 18 different wavelengths ranging from 1270nm to 1610nm, each with a unique, colorful pull ring for easy identification .10G Dual-Fiber Modules: Common wavelengths are 850nm (black), 1310nm (blue), and 1550nm (red for 40 km, red or white for 80 km) to indicate transmission distance .10G Single-Fiber Modules: Wavelengths include 1270nm (black), 1330nm (blue), 1490nm (purple), and 1550nm (yellow) for directional transmission on a single fiber .Importance of Ring Color CodingThe ring color allows quick identification of module type, wavelength, and transmission distance, which is essential for proper fiber pairing, network troubleshooting, and avoiding compatibility issues. Standardized color coding, as used by manufacturers like LINK-PP, ensures consistency across SFP, SFP+, CWDM, and BiDi modules . Always verify the module's wavelength and color before installation to ensure optimal network performance and reduce downtime.