200GBASEFR4

200GBASE-FR4 is a standard for high-speed optical networking that defines a physical layer interface for transmitting data at 200 gigabits per second. The "FR4" designation indicates a specific type of optical transceiver and its intended application. The "200G" signifies the data rate, "BASE" denotes baseband signaling, and "R4" specifies that it uses four optical lanes, each operating at 50 gigabits per second.

This standard is designed for use over single-mode fiber optic cables. Each of the four lanes utilizes a different wavelength of light within the 1310 nm band, allowing for multiplexing and demultiplexing of the signals on a single pair of fibers. This Wavelength Division Multiplexing (WDM) approach is crucial for achieving high bandwidth over optical fiber.

200GBASE-FR4 transceivers are commonly used in data centers and high-performance computing environments where substantial bandwidth is required for interconnecting switches, routers, and servers. The "FR" part of the designation typically implies a "long reach" capability, although the exact distance is dependent on factors like fiber quality and insertion loss. Compared to shorter reach variants, FR4 offers extended transmission distances, making it suitable for connecting equipment across different rows or even different parts of a large data center. The standard is part of the IEEE 802.3bs specification.