What Is a Mode Conditioning Patch Cord?

A mode conditioning patch cord is a special fiber patch cable that combines multimode fiber cable and single mode fiber cable with calibration. It is a duplex multimode fiber patch cord constructed with a length of single mode to multimode offset fiber connection part at the start of one of the two legs. Mode conditioning patch cables are 62.5/125µm or 50/125µm fiber cables assembled with fiber connectors on both ends, such as LC-LC, LC-SC, SC-ST, etc. Here’s a figure of a OM1 LC-LC mode conditioning patch cable.

The calibrated offset fiber is the key part of the mode conditioning cable. When a highly concentrated single mode fiber optic light is sent into the center of the multimode fiberglass, the transmitting laser pulse disseminates over time causing bit errors in the transmission signal. This effect is called differential mode delay (DMD). Differential mode delay results in reduced bandwidth over distance. By permitting the only mode laser launch to become offset from the center of the multi-mode fiber, the mode conditioning patch cord cuts down on the effect of such differential mode delay.