The QSFP28 100GBASE-LR 2km module is designed for data transmission using two single-mode (SM) fibers. It transmits data at speeds of up to 100 Gbps, over distances of up to 2km. It works with 4 CWDM 25Gb/s DML lasers and has 2xLC/UPC duplex optical connector type. Compliant with. Cisco ® QSFP28 100G ZR extends 100GbE coherent links from QSFP28 ports reaching up to 80km over dark fiber and up to 300km over amplified Dense Wave Division Multiplexing (DWDM) links. Shorter reaches typically utilize Vertical Cavity Surface Emitting Lasers (VCSELs), while longer reaches rely on Electro-absorption modulated lasers (EMLs) or Directly. This guide provides the definitive roadmap for selecting, deploying, and troubleshooting QSFP28 transceivers while bypassing the painful trial-and-error phase. Below, you will find comprehensive module comparisons, realistic market pricing, and precise vendor compatibility protocols to ensure a. 100G QSFP28 form factor transceivers are today heavily deployed and although the original designs of these parts consisted of EML (Electro-absorption Modulated Lasers), the quick shortage of EML availability obliged optical transceiver designers to come with an alternative solution using DML. Two types of DML and EML lasers are used in 100G optical modules.