Mosaic: Breaking the Optics versus Copper Trade-off with a Wide-and-Slow Architecture and MicroLEDs

Link technologies in today's data center networks impose a fundamental trade-off between reach, power, and reliability. Copper links are power-efficient and reliable but have very limited reach (< 2 m). Optical links offer longer reach but at the expense of high power consumption and lower reliability. As network speeds increase, this trade-off becomes more pronounced, constraining future scalability.

We introduce MOSAIC, a novel optical link technology that breaks this trade-off. Unlike existing copper and optical links, which rely on a narrow-and-fast architecture with a few high-speed channels, MOSAIC adopts a wide-and-slow design, employing hundreds of parallel low-speed channels. To make this approach practical, MOSAIC uses directly modulated microLEDs instead of lasers, combined with multicore imaging fibers, and replaces complex, power-hungry electronics with a low-power analog backend. MOSAIC achieves 10× the reach of copper, reduces power consumption by up to 68%, and offers 100× higher reliability than today's optical links. We demonstrate an end-to-end MOSAIC prototype with 100 optical channels, each transmitting at 2 Gbps, and show how it scales to 800 Gbps and beyond with a reach of up to 50 m. MOSAIC is protocol-agnostic and seamlessly integrates with existing network infrastructure, providing a practical and scalable solution for future networks.