News: Optoelectronics
28 March 2025
Coherent demos first 400G differential electro-absorption modulated laser
In booth #1519 at the Optical Fiber Communications Conference & Exposition (OFC 2025) in San Francisco (1–3 April), materials, networking and laser technology firm Coherent Corp of Saxonburg, PA, USA is demonstrating what it claims is the industry’s first 400Gb/s differential electro-absorption modulated laser (D-EML), representing a significant advance in high-speed optical networking technology for data centers.
Built on the success of its 200G D-EML, which was recognized in the 2025 Lightwave+BTR Innovation Reviews, the D-EML addresses critical challenges in optical transceiver designs for 1.6T and future 3.2T connectivity driven by explosive AI infrastructure growth. Unlike traditional single-ended EMLs, its differential design effectively doubles the signal amplitude, significantly lowering overall power consumption while minimizing crosstalk. This enables the differential EML to deliver superior optical modulation amplitude (OMA) and extinction ratio (ER) performance. An integrated on-chip termination network further optimizes electrical performance, reducing the need for extensive signal pre-conditioning and enhancing signal integrity. The D-EML builds upon proven EML technology from Coherent and is designed for use in low-cost, non-hermetic packaging solutions.
“Leveraging our vertical integration capabilities, we continue to empower the data-center market’s evolution,” says Dr Beck Mason, executive VP, telecommunications. “We also take this opportunity to thank Ciena for their support in providing a DSP chip to drive this laser for the demonstration.”
The 400G D-EML is being supplied under controlled availability upon request, while the 200G D-EML general availability is expected in 2026.
