This paper analyzes the mentioned metro + PON convergence scenario with experimental results focusing on a 400 Gbit/s fully coherent transmission (50 GBaud PM-16QAM). We characterize three different transceivers, two of which are pre-commercials. The capacity of passive optical networks (PONs) is continuously increasing, and it has been standardized up to 50 Gbit/s. The two main standardization organizations, IEEE and ITU-T, are actively working on the next-generation PON, which appears to be a 100G-PON still based on intensity modulation. (IP Infusion) (*1), a leading software company in the United States, to realize high-speed, high-capacity, and low-power consumption. Its national all-optical backbone network supports single-fiber 96 Tbit/s (highest in the industry), 6000 km ultra-long-haul transmission without regeneration, and a single-span of 400 km. It also provides the industry's first commercial OXC platform to enable all-optical OXC grooming, flexible. Segments - by Component (Optical Line Terminal, Optical Network Terminal, Optical Splitters, Patch Cords & Connectors, Others), by Application (Residential, Commercial, Industrial, Others), by End-User (Telecommunications, IT & Data Centers, Healthcare, Education, Government, Others) According to. From cloud data centers to metro and long-haul networks, 400G—particularly coherent variants like ZR and ZR+—is helping eliminate bandwidth bottlenecks and support the growing demands of AI, big data, and next-generation digital services. Unit shipments of 400G and 800G modules have grown nearly fourfold over the past 12.