At the heart of this evolution are 400G Coherent Optics, which integrate optical and electrical components to enable high-speed, long-reach communication. The Cisco 400G QSFP-DD Ultra Long-Haul Coherent Optics Module enables 400G traffic anywhere over dense wavelength division multiplexing amplified networks, and is available in both C-band and L-band. Cisco has expanded the range of 400G digital coherent QSFP-DD transceivers with the 400G QSFP-DD. As the core component of next-generation high-speed transmission, 400G coherent optical modules are emerging as critical solutions for overcoming Data Center Interconnect (DCI) and Metropolitan Area Network (MAN) bandwidth bottlenecks, reducing latency, and enhancing network security and. Nokia's 400G multi-haul coherent modules (CFP2-DCO) provide the capacity and optical reach of coherent optics in a flexible, small-sized CFP2-DCO module. Supporting 100G to 400G capacities, the Nokia CFP2-DCO is ideal for 400ZR+ optical transport applications over metro, regional and long-haul. The Optical Internetworking Forum (OIF) started a project in 2016 to standardize interoperable coherent interfaces with power budgets that could support the form factors, such as QSFP-DD and OSFP, that were expected to be deployed for 400G client optics. This type of optical module supports complex.