Converting multimode to single-mode fiber solves the MMF transmission restrictions, boosting the fiber link up to 140km. Fiber to fiber media converter, WDM transponder, and mode conditioning patch cables are three solutions for mode conversion. 📝 Why Can't You Directly Connect SMF and MMF? At its heart, the incompatibility is physical. Fiber mode conversion is required when the distance is an important parameter to consider in. In this tutorial, three methods will be introduced to support mode conversion from multimode to single-mode fibers. When Is Multimode to Single-Mode Conversion Required? If you must know one thing about fiber optic cable, it's the difference between single-mode and multimode fibers.