A team of researchers at the University of Strathclyde has developed a groundbreaking new method for assembling photonic crystal cavities (PhCCs) — minute, light-controlling structures essential for next-generation optical chips. Published in Nature Communications, the breakthrough addresses one of the most persistent challenges in the field: manufacturing large-scale arrays of PhCCs without performance-killing variations.
PhCCs are critical components in optical systems used for quantum computing, telecommunications, sensing, and photonic AI. These structures trap and manipulate light at micron and sub-micron scales, but their optical performance is incredibly sensitive to nanometer-level imperfections that inevitably occur during fabrication. As a result, producing large arrays of identical PhCCs directly on a chip has remained nearly impossible—until now.
The Strathclyde-led team’s innovation lies in their ability to physically remove and reassemble individual PhCCs from their original silicon wafer onto a new chip, while simultaneously measuring their optical performance in real time. This approach allows researchers to sort and arrange the devices by their resonant wavelength—a crucial optical property that defines how each device interacts with light.
The custom-built semiconductor integration platform, developed in-house at Strathclyde, enables high-precision manipulation of individual PhCCs with a level of throughput and accuracy previously unseen. In one session, the team successfully transferred and sorted 119 PhCCs, building a tailored array that would be impossible to fabricate through conventional lithography alone.
Lead author Dr. Sean Bommer described the advance as a shift in the design process: “Using previous methods, assembling these devices felt like building a Lego set, but where you didn’t know the colour of any particular brick. Now that we can measure their performance during assembly, it unlocks the potential to make more effective and complex designs.”
The platform also offered unique insights into how the devices respond mechanically to the transfer process. Researchers observed real-time elastic and plastic changes that evolved over seconds to hours—data that could inform better device stability and durability in future designs.
Professor Michael Strain, Fraunhofer and RAEng Chair in Chipscale Photonics at Strathclyde, called the development a “crucial step” in enabling larger and more complex integrated photonic systems. Future work is already underway to integrate a wider range of semiconductor components onto single chips, opening new possibilities in quantum technologies, advanced telecoms, and high-precision sensing.
The project was conducted in partnership with MIT and received support from the Royal Academy of Engineering, EPSRC, and Innovate UK.
Image & article source: University of Strathclyde
