Appendix: Optical Connector and Patch Cable
The optical port in the MMA1L10-CR 100GBASE-LR4 optical transceiver is a duplex LC receptacle.
The cable to use between transceivers of this type is a two-fiber single-mode cable, terminated in duplex LC connectors.
Two fiber single mode cable with duplex LC connectors
One fiber for transmitting, the other for receiving.