Coherent is demonstrating the industry’s first 400G Differential Electro-Absorption Modulated Laser (D-EML) at OFC 2025, signaling a major leap in photonic integration for next-generation data center transceivers. The new 400G D-EML targets key technical challenges in building low-power, high-performance optical engines for 1.6T and future 3.2T interconnects required by rapidly scaling AI infrastructure.
The differential EML architecture doubles the signal amplitude compared to traditional single-ended EMLs, enhancing optical modulation amplitude (OMA) and extinction ratio (ER) while reducing power consumption and minimizing crosstalk. It also integrates an on-chip termination network, improving signal integrity and simplifying electrical design by reducing the need for complex pre-conditioning. The device builds on Coherent’s proven 200G D-EML platform, which is expected to enter general availability in 2026.
Coherent’s vertically integrated manufacturing model allows this 400G laser to be produced using low-cost, non-hermetic packaging, making it suitable for volume deployment in data center environments. The laser will be shown live at OFC 2025, powered by a DSP chip provided by Ciena for the demonstration. Controlled samples are now available to select partners.
• Industry’s first 400G Differential Electro-Absorption Modulated Laser (D-EML) debuts at OFC 2025.
• Differential design doubles signal amplitude, improves OMA/ER, and reduces crosstalk.
• On-chip termination network boosts signal integrity and simplifies electrical integration.
• Optimized for 1.6T and 3.2T interconnects in AI-scale data centers.
• Suitable for low-cost, non-hermetic packaging; available under controlled release.
“This pioneering differential EML design underscores our commitment to innovation and technology leadership,” said Dr. Beck Mason, Executive Vice President, Telecommunications at Coherent. “Leveraging our vertical integration capabilities, we continue to empower the data center market’s evolution.”
