Traditionally, SFP is a single-mode fiber, meaning that signals can only travel in one direction at a time. Higher-order modes like LP 11, LP 20 etc. It can transmit higher bandwidth than multimode fiber but requires a light source with a limited spectral range. The terms single-mode. Recommendation ITU-T G. 652 fibre was originally optimized for use in the 1310 nm wavelength region, but can also be used in. Mixing single-mode and multi-mode transceivers creates major optical and hardware problems. This leads to unreliable network performance. Here's why: Light source & beam profile: SM lasers are narrow and Coherent; they couple efficiently into a 9 µm core.