Researchers from Washington University in St. Louis, the Swiss Federal Institute of Technology in Lausanne, and the Massachusetts Institute of Technology have developed a new technique for combining different types of optical materials on a single chip. This method uses ultra-thin, single-crystal materials known as nanomembranes. These membranes are first grown on specialized surfaces, then carefully removed and placed onto other optical structures. This process uses van der Waals forces—weak attractions between molecules—to stick the membranes together without requiring precise atomic alignment, which is a common challenge in traditional methods. Published in the journal Nature, the research demonstrates how these nanomembranes can be combined in various ways, much like stacking building blocks, to add new optical properties to existing photonic systems. For instance, a material called barium titanate (BTO) was transferred onto a silicon chip. This material is known for its ability to change light properties when an electric field is applied. The team achieved an impressive performance, with a measure of efficiency that was over 30 times better than commonly used materials like lithium niobate. They also created a device with a high-speed response, operating above 23 GHz, which is crucial for high-performance optical communication systems. The researchers also used similar techniques to place thin films of gallium arsenide and gallium nitride onto silicon nitride structures. These materials are known for their ability to detect light across a wide range of wavelengths, from ultraviolet to near-infrared. Additionally, they integrated a magnetic material called cobalt ferrite onto silicon microring resonators, achieving an extraordinary magnetic effect that allows light to be controlled in one direction only, a property useful for optical switches and isolators. This magnetic effect remained even after removing the external magnet, making it practical for real-world applications. By stacking different nanomembranes vertically, the team showed how they can create complex, multifunctional devices. In one experiment, they placed both the electrically responsive BTO and the magnetically responsive cobalt ferrite on top of a silicon microring. This combination allowed the device to control light using both electric and magnetic fields, something that is difficult to achieve with traditional methods. The technique allows for high-quality integration of materials at both small and large scales, opening up new possibilities for advanced photonic devices. This breakthrough provides a versatile platform for combining different optical materials in ways that were previously difficult. It could lead to improvements in optical communication systems, sensors, and even quantum technologies. The method also offers a new way to study how different types of materials interact at the atomic level, potentially leading to new discoveries in material science and photonics.