Our 100G-ER1 Single Lambda QSFP28 40km transceiver delivers ultra-extended reach using advanced PAM4 modulation. Supporting 40km over single-mode fiber with FEC at 1304. In Proceedings of the 2019 21st International Conference on Advanded Communication Technology (ICACT), PyeongChang, Korea, 17–20 February 2019. These authors contributed equally to this work. This article explores the technological underpinnings, design benefits. Utilizing advanced PAM4 modulation, QSFP28 100G PAM4 DWDM transceiver supports up to 4Tb/s of bandwidth over a single fiber and the transmission distance allows for up to 80km. What Does. QSFP28 (Quad Small Form-Factor Pluggable 28) is a compact transceiver form factor designed for high-capacity 100G Ethernet. 25Gbps PAM4 Ethernet Applications. It is a high performance module for short-range data communication and interconnect applications which operate at 106.