# Penn Physicists Build Exciton-Polariton Chip That Switches All-Optical Signals With 4 Femtojoules, Pointing to Far Lower AI Energy Costs

*2026-05-20 02:02 UTC · Science · 1 min read*

> Penn researchers led by Bo Zhen demonstrated an exciton-polariton all-optical switch using just 4 femtojoules, a step toward photonic chips that could slash AI energy demand.

Researchers at the University of Pennsylvania have demonstrated an all-optical switch built on exciton-polaritons, hybrid light-matter quasiparticles formed by coupling photons with electrons in an atomically thin semiconductor. The work, led by Jin K. Lee Presidential Associate Professor Bo Zhen of Penn's Department of Physics and Astronomy, was reported on May 18, 2026.

The team showed light-to-light switching using only about 4 quadrillionths of a joule (4 femtojoules) of energy — far below what it takes to briefly power a small LED. Because the particles inherit photons's speed and electrons's ability to interact strongly, they can route optical signals without round-tripping back to electronics, removing a major bottleneck in today's photonic computing designs.

If the platform scales, photonic chips built on this principle could process data directly from cameras and sensors without repeated optical-electrical conversions, and could meaningfully cut the energy footprint of large AI systems whose power demand is now a binding constraint on data-center buildout.

## Sources

- [sciencedaily.com](https://www.sciencedaily.com/releases/2026/05/260518041341.htm)
- [penntoday.upenn.edu](https://penntoday.upenn.edu/news/making-light-work-computing)
- [photonics.com](https://www.photonics.com/Articles/Hybrid-Particle-Points-Toward-Ultrafast-Optical/p5/a72186)

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TechTools News · https://techtools.cz/tools/news/article/1678-penn-physicists-build-exciton-polariton-chip-that-switches-all-optical-signals
Česká verze: https://techtools.cz/tools/news/clanek/1751-fyzici-z-pennu-sestavili-exciton-polaritonovy-cip-ktery-prepina-ciste-svetelne