Researchers at the University of Strathclyde have developed a groundbreaking method for assembling ultra-small, light-controlling devices, paving the way for scalable manufacturing of advanced optical systems used in quantum technologies, telecoms and sensing.
The breakthrough, published in Nature Communications, centres on photonic crystal cavities (PhCCs), micron-scale structures that trap and manipulate light with extraordinary precision. These are essential components for high-performance technologies ranging from quantum computing to photonic artificial intelligence.
Until now, the creation of large arrays of PhCCs has been severely limited by the tiny variations introduced during fabrication. Even nanometre-scale imperfections can drastically shift each device’s optical properties, making it impossible to build arrays of identical units directly on-chip.
The Strathclyde-led team designed a method which can physically remove individual PhCCs from their original silicon wafer and place them onto a new chip, while precisely measuring and sorting each one by its optical characteristics in real time.
Bespoke system
Making use of a bespoke semiconductor device integration system, designed and built at Strathclyde, researchers can manipulate and position microscopic photonic devices with unprecedented accuracy and throughput, marking a major step toward scalable manufacturing.
Dr Sean Bommer from Strathclyde and lead author of the paper said: “This is the first system of its kind that allows optical measurement of these devices as they are integrated.
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.
In a single session, the team successfully transferred and ordered 119 PhCCs by resonant wavelength - the specific wavelength of light that a material or object will absorb or transmit most strongly - creating a bespoke array impossible to fabricate by traditional methods. The integration platform also allowed researchers to observe for the first time how the devices dynamically respond to the printing process, revealing elastic and plastic mechanical effects over timescales from seconds to hours.
Crucial step
Professor Michael Strain, Fraunhofer & RAEng Chair in Chipscale Photonics, added: “The ability to rearrange these microscopic devices after they have been fabricated is a crucial step in making use of them as elements in larger scale circuits.
“We’re now working towards assembling a diverse range of semiconductor devices onto a single chip to create complex, high-performance systems for telecoms, quantum applications, sensing and beyond.”
The research was carried out in collaboration with Professor Dirk Englund of the Massachusetts Institute of Technology (MIT) and funded by the Royal Academy of Engineering, EPSRC and Innovate UK, part of UK Research & Innovation.