Workshop: IM-DD vs Coherent Lite for Intra- and Inter-Building Data Center Interconnects

Inside the data center, encompassing both intra- and inter-building campus links, optical interconnect technologies must deliver ever-increasing data rates under stringent constraints on cost, power, latency, and operational simplicity.

Intensity modulation direct detection (IM-DD) has been the dominant solution for this application due to its low complexity and high energy efficiency. However, as data rates scale toward 200 Gb/s per lane and beyond, IM-DD systems increasingly face fundamental RF bandwidth limitations of electrical and electro-optic components, leading to increased DSP complexity and reduced reach.

In contrast, emerging Coherent Lite architectures, targeting reaches of 2–20 km, leverage coherent detection to better tolerate chromatic dispersion and bandwidth limitations, with reduced DSP/FEC complexity, making them an increasingly viable alternative for this application. Despite these advances, Coherent Lite solutions continue to face challenges in cost, power, and integration, leaving their suitability for high-volume, short-reach data center links an open question.

This workshop will bring together experts from academia, device/equipment manufacturers, and data center operators to discuss whether, when, and how Coherent Lite can meaningfully encroach on IM-DD’s traditional territory within data centers.

The discussion will also explore the technical, economic, and architectural breakthroughs required for both IM-DD and Coherent Lite to become viable at reaches below 2 km at data rates of 200 Gb/s per lane and beyond.