Currently, 400G QSFP-DD transceivers use 8 pairs of MMF to transmit signal in short distance, while bidirectional (BiDi) technology enables users to save the fibers for new data center deployment or maximize their usage of the existing fiber cabling infrastructure. the following article briefly explains the latest connector for QSFP-DD BIDI transceivers.
1. MPO Optical Cable connections
The optical plug and receptacle for the MPO-12 connector are specified in TIA-604-5. Aligned keys are used to ensure alignment between the modules and the patch cords. The optical connector is orientated such that the keying feature of the MPO receptacle is on the top. Note: Two alignment pins are present in each receptacle.
2. SN Optical Cable connections
The SN optical connector and receptacle for QSFP-DD module is specified in SN-60092019. The top key and offset bottom key are used to ensure alignment between the modules and the patch cords.
3. MDC Optical Cable connection
The MDC optical plug and receptacle for a QSFP-DD module is specified in USC-11383001. The optical connector is orientated such that the keying feature of the MDC receptacle is on the top.
Source from: QSFP-DD HARDWARE SPECIFICATION FOR QSFP DOUBLE DENSITY 8X PLUGGABLE TRANSCEIVER REV 5.0