A 400G optical module performs photoelectric conversion: With a 400 Gbps transmission rate, these modules support industry evolution from 100M → 1G → 25G → 40G → 100G → 400G → 1T. They form the backbone of high-throughput data center networks and AI clusters. To address these demands, operators are increasingly adopting 400G optical modules—compact, pluggable transceivers capable of delivering up to 400 Gbps per port. This shift is driven by multiple forces: hyperscale data centers require greater east-west bandwidth to support massive internal data. PAM4 (4-Level Pulse Amplitude Modulation): This is the predominant modulation technique used in 400G modules. Multi-Mode Fiber (MMF):. With 400G modules now the baseline, 800G adoption is surging—especially across AI and hyperscaler environments—while 1. 6T modules edge closer to reality. This article unpacks the technologies powering this leap (silicon photonics, advanced modulation, and co-packaged optics), compares deployment. Integrated circuits and reference designs help you create a smaller and faster optical module design used in high-bandwidth data communication applications. Nokia coherent routing utilizes a new generation of digital coherent optics (DCOs) equipped in router interface ports to n the router-pluggable QSFP-DD format. As transmission speeds move from 56G PAM4 to 112G PAM4 and beyond, PCB technology has become one of the most critical.