Deep|Optics: OCS Content per Accelerator Grows with Each Generation as Demand Widens Beyond Google

A year ago, optical circuit switches were mostly a Google program with one outside supplier shipping under $10m a quarter. Lumentum now expects its September-quarter OCS revenue to exceed $100m, and we believe its OCS revenue will pass $2.5b next year. TPU 8i put OCS ports into inference pods for the first time and the 6D torus would give the next training chip four times as many OCS ports as today.

Demand for OCS is widening beyond Google. We expect Nvidia to adopt OCS once their scale-up domains pass eight racks, from late 2028. We see more than $20b a year of OCS demand by 2030. Lumentum leads merchant OCS shipments today, and Coherent is the other US-listed supplier. Google remains the only hyperscaler confirmed to buy OCS and nothing at Nvidia is in production yet.

An OCS connects one fiber to another with a mirror, a liquid crystal cell or a chip and leaves the light untouched. With no transceiver and no DSP inside it, the same switch works at 800G, 1.6T or 3.2T and uses about 80% less power than a packet switch on Lumentum's figures. Google has run OCS in their datacenter network for a decade and in their TPU pods since TPU v4. Until last year they built almost all of their switches themselves. Below is an illustration from Lumentum of how an OCS can fit within a datacenter.

Image 1: Four uses of OCS in AI datacenters, DCN spine replacement, DCI, scale-out topology reconfiguration and scale-up. Source: Lumentum.