400G Product Optical Module

A 400G optical module is a high-speed transceiver capable of 400 Gbps data transmission, using advanced modulation and multiple lanes to support modern data center and network applications.

Overview

A 400G optical module is designed to handle data rates of 400 Gbps, forming the backbone of high-throughput networks, AI clusters, and modern data centers. These modules perform photoelectric conversion and use advanced modulation techniques like PAM4 (4-level Pulse Amplitude Modulation), which allows each symbol to carry two bits, effectively doubling the data rate per lane compared to traditional NRZ. Common Form Factors and StandardsQSFP-DD (Quad Small Form Factor – Double Density): Backward-compatible with QSFP/QSFP28, supports 8 lanes for 400G.

OSF

P (Octal Small Formfactor Pluggable): New interface, not backward-compatible, designed for high-density deployments. CFP8, CWDM8, CDFP, COBO: Other 400G standards with varying channel counts, fiber types, and deployment scenarios. Types of 400G ModulesSR4/SR8: Short-range multimode fiber modules, ideal for intra-data center connections.

SR4 typically supports 100 meters on OM4 fiber, while SR4. 2 extends up to 150 meters using wavelength division multiplexing. DR4: Popular for hyperscale data centers, using parallel single-mode fiber for medium-range links.

FR4: Uses CWDM over duplex single-mode fiber, reducing fiber count while maintaining 400G bandwidth. LR4: Long-range single-mode fiber modules for campus or metro networks.

High-

Power Coherent Modules (e.g., Cisco QSFP-DD Bright): Support coherent DP-mQAM signaling in the C-band, with enhanced Tx power for long-distance DCI, metro, and cloud interconnects.

Key Features

Transmission Distance: Varies by type; SR modules are short-range, DR/FR modules are medium-range, LR and coherent modules support long distances. Fiber Type: Multimode for SR, single-mode for DR, FR, LR, and coherent modules. Channels and Lanes: Typically 4–8 lanes, each carrying 50–100 Gbps, combined to achieve 400G.

Breakout Capability: Many 400G modules can be split into multiple lower-speed ports, e.g., 4x100G. Applications: Data center interconnects, cloud computing, high-performance computing, enterprise networks, and metro/long-haul networks.

Choosing the Right Module

When selecting a 400G module, consider: Transmission Distance: Short-range (SR) vs. long-range (LR) requirements. Existing Fiber Infrastructure: Duplex vs. parallel fiber, multimode vs. single-mode. Power and Thermal Constraints: High-density environments may require low-power modules.

Application Needs: Ethernet, OTN, or coherent transport for long-haul links. In summary, 400G optical modules provide flexible, high-bandwidth solutions for modern networks, with multiple form factors, modulation techniques, and fiber compatibility options to meet diverse deployment scenarios.