Cisco has expanded the range of 400G digital coherent QSFP-DD transceivers with the Cisco® 400G QSFP-DD ER1 optical module. Leveraging coherent technology innovations, the QSFP-DD ER1 optical module can transmit a single wavelength of 400G traffic directly from a router port up to a 45 km distance. The 400G QSFP-DD ER1 optical module’s small size and low power consumption make it an optimal choice for unamplified point-to-point dark fiber applications including data center interconnect, campus interconnect, wireless backhaul, and metro access/aggregation.