Fiber mode conversion is the process of changing a multimode fiber (MMF) into a single mode or vice versa. This guide will break down the professional methods to achieve seamless single-mode to multi-mode conversion, ensuring your network integrity and performance. 📝 Why Can't You Directly Connect SMF and MMF? At its heart, the incompatibility is physical. Fusion splicing is the most widely used method of splicing as it provides for the lowest loss and least reflectance, as well as providing the strongest and most reliable joint between two fibers. Fiber to fiber media converter, WDM transponder, and mode conditioning patch cables are three solutions for mode conversion. A lightwave with a certain frequency, polarization.