Components of 100g and 400g optical modules

100G and 400G optical modules share core components such as optical transmitters, receivers, DSPs, and electrical interfaces, with 400G modules incorporating more advanced signal processing and higher channel density.

100G Optical Modules

100G optical modules are typically packaged in QSFP28 form factors and consist of four independent 25Gbps optical channels . The main components include:

• Optical Transmitter Unit (OTU): Converts electrical signals into optical signals using laser diodes. Each channel has its own laser .
• Optical Receiver Unit (ORU): Detects incoming optical signals and converts them back into electrical signals using photodetectors .
• Drive Circuits: Control the laser output power and modulation of the optical signals .
• Optical-Electrical Interface: Connects the module to the host system, enabling data transmission and reception .
• Housing and PCB: Provide mechanical support, electrical routing, and thermal management . Each 100G module handles 100Gbps by aggregating four 25Gbps channels, making it suitable for data center interconnects and high-speed network links .

400G Optical Modules

400G optical modules are available in QSFP-DD or OSFP form factors and are designed for ultra-high-speed data transmission . Their components include:

• Digital Signal Processor (DSP): Central to 400G modules, the DSP converts input electrical signals into four 100G PAM4 signals for transmission and performs complex signal processing on received signals, including compensation for chromatic dispersion, polarization mode dispersion, and carrier recovery .
• Optical Transmitter Unit: Converts the DSP-processed electrical signals into optical signals using multiple laser channels .
• Optical Receiver Unit: Converts incoming optical signals back into electrical signals for the DSP to decode .
• Monitoring Unit: Tracks module performance, temperature, and signal integrity .
• PCB and Housing: Integrate all components, provide electrical routing, and manage heat dissipation . 400G modules support higher bandwidth and port density, making them ideal for advanced data centers, cloud computing, and high-capacity backbone networks . They often include coherent optics and advanced modulation schemes to achieve long-distance transmission and high spectral efficiency .

Summary

While both 100G and 400G optical modules share fundamental components such as transmitters, receivers, and electrical interfaces, 400G modules incorporate DSPs, higher channel density, and advanced signal processing to handle the increased data rate. The evolution from 100G to 400G reflects the need for higher throughput, improved bandwidth efficiency, and support for demanding applications like AI, high-definition video, and large-scale cloud services .