576 GPUs across eight racks can't talk to each other over copper - that distance demands light, and light starts with indium phosphide wafers. Coherent just broke ground on an expanded manufacturing building in Sherman, Texas, to make those wafers at scale. The company runs what it calls the world's first 6-inch indium phosphide fab, and this expansion directly feeds AI's optical backbone.
Why AI Systems Depend on Indium Phosphide
When NVIDIA Vera Rubin Ultra NVL576 links 576 GPUs into a single system, copper can't carry the signal across eight racks. Retimers and signal conditioning burn power that should go to compute. Optics pays a one-time penalty to convert electrical to light - after that, distance is nearly free. Coherent supplies the lasers, transceivers, and pluggable optical modules that plug into NVIDIA's Spectrum-X Photonics and Quantum-X Photonics switches. Each module carries an indium phosphide laser. Without these, AI clusters the size of football fields would choke on interconnect bandwidth.
The 6-Inch Wafer Advantage
Most of the world's InP production runs on 3- or 4-inch wafers - lower yields, fewer components per run. Moving to 6-inch wafers roughly quadruples usable area (area scales with diameter squared), driving down cost and unlocking volume. Coherent's Sherman fab is already the most advanced 6-inch InP line in the world. "It took 50 years to build the first line," NVIDIA CEO Jensen Huang said. "In one year, they've quadrupled it." The same lithography, photoresist, and etching processes used in silicon fabs apply here, but the substrate is exotic compound semiconductors tuned for precise optical properties.
What Gets Built and Where It Goes
The factory ships pluggable optics roughly the size of a USB stick that plug into the front of NVIDIA networking switches. These move data between racks across the data center floor where copper can't reach. Coherent also supplies the external laser module for co-packaged optics in NVIDIA switches. The expansion is backed by a $50 million CHIPS Act grant, a $2 billion NVIDIA investment, and a multibillion-dollar purchase commitment for advanced laser and optical networking products. When fully operational, the site will support more than 550 direct jobs and thousands indirect.
With this expansion, Coherent aims to turn Sherman into a linchpin of U.S. optical manufacturing for the AI era - a decade from now, we may look back and see this as the moment the domestic supply chain for AI's optical backbone was secured.
Source: Coherent Breaks Ground on Expanded Texas Facility, Scaling AI's Optical Backbone
Domain: blogs.nvidia.com
Comments load interactively on the live page.