Mode conditioning patch cords are utilized when 1000BASE-LX/LH, 10GBASE-LX4 and 10GBASE-LRM transceivers are used over legacy multimode fiber cables. Because these transceivers have to operate for both single mode and multimode fiber. They are equipped with single mode laser source of 1300/1310 nm, which is different from the LED source that legacy multimode fiber cable can tolerate.
In Gigabit Ethernet networks, when we deploy 1000BASE-LX/LH switches, routers, or optical transceivers in existing multimode system, we need to use mode conditioning patch cable. In the 10 Gigabit Ethernet networks, even though there’s choice to shift to 850 nm laser-optimized 50/125µm OM3 or OM4 multimode fiber cables, some users still want to remain the legacy fiber distributed data interface (FDDI)-grade, OM1, or OM2 multimode fiber cabling instead of rebuilding the network with OM3/OM4. Then 10GBASE-LX4 and 10GBASE-LRM modules can be the right path to 10G multimode on the premise that mode conditioning patch cord is used.