The structure of 200G optical module mainly includes the following aspects:
Packaging form: 200G optical module adopts QSFP56 packaging, which is a hot-swappable packaging form with 4 independent transmitting and receiving optical signal channels, and the transmission rate of each channel is 50G, thus achieving a total 200G transmission rate.
Modulation technology: 200G optical module adopts PAM4 modulation technology instead of traditional NRZ modulation technology. PAM4 can transmit 2bit of logical information per clock cycle, so under the same baud rate conditions, the throughput of PAM4 is twice that of NRZ. This technology can increase the transmission rate without increasing the fiber bandwidth, effectively improving the bandwidth utilization.
Interface type: According to different transmission distances and application scenarios, there are many types of 200G QSFP56 optical modules, such as SR4, DR4, FR4, LR4, ER4, etc. For example, 200G QSFP56 SR4 is suitable for short-distance transmission, and the transmission distance can reach up to 100 meters with multimode optical fiber; while 200G QSFP56 DR4 is suitable for medium-distance transmission, and the transmission distance can reach up to 500 meters through single-mode optical fiber.
Application scenario: 200G optical modules are particularly suitable for use in ultra-large-scale data center networks, and can transmit more data on existing optical fibers, saving optical fiber costs and reducing link losses. For example, 200G QSFP56 FR4 optical modules are widely used for medium-distance interconnection between devices inside data centers, and the transmission distance can reach up to 2 kilometers through dual-core single-mode optical fibers.