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. A TPU in Google’s 3D torus has 1.5 OCS ports. Google’s inference pods had none until TPU 8i, which links 36 groups of chips through OCS at about 1.25 ports per chip. The 6D torus reported for the next training chip would take the count to six ports per chip from 2027, or three if two transceivers share a port. Nvidia has no OCS in production. Direct fiber links tie up to eight racks together. Beyond eight racks, our model gives each GPU four ports, $800–1,200 of content at $200–300 a port. Some of this is already in reported numbers. Lumentum targets $400m of OCS for the second half of 2026 on a backlog from three customers. Coherent doubled its addressable market estimate to $4b by 2030 between February and March. Nvidia took part in iPronics’ $125m round on September 2. We attended ECOC in Málaga in late September and met with teams from Oriole Networks, Salience Labs, iPronics, LightDance and others. OCS was one of the topics discussed during the week. This note updates the OCS market outlook and presents both the bull case and the pushback we heard from the industry. The companies discussed in this report include: 1. Lumentum 2. Coherent 3. Huber+Suhner 4. Google 5. Nvidia 6. Broadcom 7. Marvell 8. Astera Labs 9. Arista Networks 10. Ligent 11. nEye (private) 12. iPronics (private) 13. Salience Labs (private) 14. LightDance (private) 15. Oriole Networks (private) Detailed Report