HWBRIEF
Harvard and Max Planck used algorithmic design to shrink photonic components roughly 500x smaller than conventional designs — and the same week, a Seoul team showed the same kind of chip can slow, store, and reshape light on demand.
Two photonic-chip advances landed the same week, and both rest on the same lever: instead of a human hand hand-drawing each waveguide, an optimization algorithm shapes the layout to fit a commercial foundry's process.
Harvard and the Max Planck Institute used inverse-design algorithms (software that proposes a layout and improves it against a target) to produce silicon nitride photonic components roughly 500 times smaller than conventional designs. One chip now integrates three device classes that previously lived apart: wavelength splitters, mode sorters, and on-chip cavity mirrors. The team built manufacturing-variation robustness and minimum-feature-size rules into the optimizer, so the layouts drop into a commercial foundry flow. Toby Bi of Max Planck: "Inverse design lets us define what we want light to do, and the optimization finds a structure that does it, often one no human would have drawn." In follow-on work, the group will combine these parts with nonlinear optical circuits to generate optical frequency combs, which are light sources that split one color into many evenly spaced tones for sensing and clocks.
That same week, a Seoul National University and University of Seoul team reported a programmable photonic integrated circuit that uses two tunable loop couplers to slow, store, and reshape light on demand. Together the demonstrations point past the lab: denser, foundry-compatible photonic circuits are a precondition for cheaper optical interconnects and sensors, and eventually on-chip optical computing.
What remains open: both are research demonstrations, not shipping products, and the inverse-design claims still await independent fabrication-process confirmation at the published scale.