NADDOD QDD-400G-FR4 optical transceiver features a duplex LC connector and supports transmission distances of up to 2 km over parallel single-mode fiber. It converts eight 50 Gb/s PAM4 electrical signals into four CWDM optical channels, multiplexed into a single 400 Gb/s optical. The 4x 100G QSFP-DD FR1 optical transceiver that provides 4 parallel 100GE links over 4 single mode fiber (SMF) pairs via its MPO-12 connector. The module is compliant with the QSFP-DD MSA, IEEE 802. 3bs, and. MaxLinear's highly integrated PAM4 DSPs offer superior link-margin performance and low power to enable 100G, 400G, 800G, and 1. 6T optical interconnects inside the data center. While SFP+ (10G) and SFP28 (25G) used NRZ (Non-Return to Zero) modulation, SFP56 utilizes PAM4 (Pulse Amplitude Modulation 4-level). Implication: You cannot plug an SFP56 module into an SFP28 port and expect it to auto-negotiate 50G without specific host support for PAM4 decoding. The 400 Gigabit Ethernet signal is carried over four parallel and independent Single Lambda 100G PAM4 lanes. 400GBASE-XDR4 uses MTP/MPO-12 connector.