Caltech prints optical-fiber glass circuits on silicon wafers at near-fiber loss
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Caltech researchers have printed optical circuits from the same glass used in optical fiber directly onto 8- and 12-inch silicon wafers, achieving visible-wavelength signal loss approaching that of optical fiber. The team reports the technique in Nature and says it could enable highly coherent, energy-efficient photonic integrated circuits for optical clocks, gyroscopes, AI data-center communications, and quantum computing.
Key Facts
- The team printed optical circuits from germano-silicate — the same glass used in optical fiber — directly onto 8- and 12-inch silicon wafers.
- The waveguides are laid out in spirals, allowing light to follow a much longer optical path while staying inside a very small on-chip area.
- The researchers report the technique in Nature, with Caltech postdoctoral scholar Hao-Jing Chen and graduate student Kellan Colburn as lead authors.
- Kerry Vahala says the advance delivers near-fiber performance in visible bands and will enable technologies with negligibly low circuit energy loss.
- Henry Blauvelt, a visiting associate at Caltech and CTO of Emcore, says the waveguides also transfer light efficiently between optical fibers and semiconductor lasers.
Waveguide Fabrication
Caltech researchers fabricate waveguides from germano-silicate, the same glass used in optical fiber, adapting it to a lithography-based process compatible with computer-chip wafers. Vahala says the team spent years translating spool-based optical-fiber fabrication to silicon wafers while trying to preserve ultralow loss. The waveguides are printed directly onto 8- and 12-inch wafers, the standard sizes used for computer chips. Instead of straight paths, the waveguides are arranged in spirals, similar to winding fiber around a spool but in a far smaller footprint.
Visible-Band Performance
On 8- and 12-inch wafers, the team measured visible-wavelength propagation with loss approaching that of optical fiber. Optical fiber achieves ultralow loss because its glass is extremely pure and its surface is exceptionally smooth. Lead authors Hao-Jing Chen and Kellan Colburn carried out the work in Vahala's Caltech lab. The team reported the technique in a paper published in Nature.
Applications and Energy Use
Vahala says the fiber-like performance, especially in visible bands, will enable technologies that benefit from negligibly low circuit energy loss. Potential uses include optical clocks, gyroscopes, AI data-center communications, and quantum computing. Henry Blauvelt, a visiting associate at Caltech and CTO of Emcore, says the waveguides also transfer light efficiently between optical fibers and semiconductor lasers. Blauvelt says that efficient transfer is important for reducing the overall energy cost of server infrastructure.
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Caltech prints optical-fiber glass circuits on silicon wafers at near-fiber loss
