HWBRIEF
UC Berkeley's tiny micro mirror chip routes light between fibers using post processing added after standard silicon photonics (light on a chip) manufacturing, skipping the bespoke steps that gate today's deployed optical switches.
UC Berkeley researchers built a chip-scale optical switch that routes data-carrying light between fibers using a process compatible with standard silicon photonics production lines. The result, posted on arXiv on August 4 and picked up by Semiconductor Engineering a day later, sidesteps the bespoke process steps that have limited today's deployed optical circuit switches (OCSes).
An optical circuit switch is the device that re-routes optical fibers at data-center scale, deciding which rack of GPUs talks to which other rack. Most shipping OCS hardware uses free-space micro-mechanical mirrors. Berkeley's team instead added MEMS functionality through Back-End-of-Line post-processing on a standard silicon photonics stack, with Arkadev Roy as submitting author under Ming Wu.
The reported envelope: more than 30 dB extinction ratio in the C-band, less than 1.5 dB insertion loss, and roughly 20 nW of static power. None of those numbers is a category record for a single switch element. The point is the process: the foundry layer stack stays unchanged, so the device can be built on the same lines that already produce silicon photonics chips for datacom and sensing.
The paper positions the work against Google's deployed 3D-MEMS free-space OCSes, arguing the silicon-photonics path offers co-integration and mass-manufacturability advantages. That's a paper-stage claim, not a shipped product: reliability, scale, and integration with real switch fabrics remain unproven. The broader foundry landscape is moving toward mass production of silicon photonics, which is why a "zero-change" process is the live commercial question this week.