[OFC 2026] Part 4 of 5: 400G/Lane and 1.6T Coherent: Two Fronts, One Power Wall
Broadcom, Coherent, Cisco, Nokia, and Ciena
Two Fronts
Datacenter optical interconnects are pushing density on two fronts simultaneously. One is scaling IM-DD (Intensity Modulation / Direct Detection) lane rates from 200 Gb/s to 400 Gb/s. The other is scaling coherent pluggables from 800 Gb/s to 1.6 Tb/s. The two fronts look independent, but they are deeply entangled. Once 400G/lane IM-DD becomes prevalent, routing systems will shorten the electrical traces between the switch ASIC and the optics, accelerating CPO/NPO adoption. At that point, coherent line optics get pushed out of the router chassis and back into standalone transport platforms.
Six papers from OFC 2026 map the current technical coordinates of these two fronts. The thesis: 400G/lane IM-DD and 1.6T coherent pluggables are each approaching their physical limits, and the tradeoff structures for pushing past those limits are fundamentally different. Not a single one of the six papers showed a measured link demonstration.
Six Papers at a Glance
IM-DD vs Coherent: Technology Positioning
From here I break down each paper’s technical substance, cross-compare across papers, and extract structural insights for the value chain.
