A team of researchers, headed by Professor Andreas Tittl at Ludwig Maximilian University (LMU), have accomplished a breakthrough in optical technology. Together, they created a new way to produce planar or ultrathin optical components that are sensitive or react strongly to very faint light. This radically new approach merges metasurface physics with stacked two-dimensional (2D) material structures. These materials are structures composed of single layers of one to two atomic planes thick. Results of this study appear in the journal Nature Photonics. They promise groundbreaking novel devices such as ultra-high sensitivity sensors, low-power computing, and advanced optical communication.
It was these cavities that the research team, led by key contributor Luca Sortino, worked tirelessly to stack. Their work centered on the development of van der Waals heterostructure metasurfaces. The researchers have engineered these structures to be responsive to light intensities that are more than 1,000 times dimmer than anything previously reported. This accomplishment establishes the new benchmark in effective light control. These resonators are photonic, meaning they control light, and they operate at the nanometer scale. They can dynamically control the amplitude, phase, and polarization of all incoming electromagnetic waves, including visible light.
Innovative Manufacturing Process
The team’s approach uses a type of material known as van der Waals materials, an important frontier of modern materials research. Tittl elaborated on the process by stating, “You can buy these materials in crystal form, remove individual layers under the microscope, and stack them kind of like paper.” The invention of this method gave scientists an unprecedented control over the positioning of each layer, which resulted in a better interaction with light.
Perhaps, in all of this, no one contributed more to the study of atomic-layer assembly than Luca Sortino. He noted that instead of using external optical resonators or placing 2D materials on pre-existing nanostructures, “we worked the resonance structure directly into the vdW stack.” This integration leads to much stronger light-matter interactions that are crucial for improving the performance of optical devices.
The researchers sandwiched one single semiconducting layer of tungsten disulfide (WS2) between protective layers of hexagonal boron nitride. This design serves a dual purpose, shielding the delicate layers while intensifying their engagement with incoming light.
Ultrathin Resonators and Their Properties
The ultrathin resonators that Tittl and his team created share characteristics of matter and light. They can condense like a Bose-Einstein condensate, marking a revolutionary success in material science and optics. With such unprecedented efficiency at being able to harness and manipulate all types of light, this provides a platform for so much technology.
What we didn’t have was a toolkit for bringing the two materials science concepts together,” Sortino said. This includes opening up the model to a whole new class of 2D materials. This level of design flexibility and application versatility puts the researchers on the leading edge of future advances in optical technology.
Achim Hartschuh’s group at the Technical University of Munich was an essential contributing partner in this collaborative effort. Next, they zeroed in on improving the applications of these ultrathin resonators. The collaboration speaks to the value of interdisciplinary teamwork in moving forward scientific research.
Future Implications
The possible uses for such ultrathin components and the technologies they could enable are enormous. Tittl anticipates that they could lead to “tiny, more sensitive sensors, more energy-efficient computer components, and faster optical communication.” Such progress, if accompanied by other breakthrough technologies, has the potential to transform many sectors from telecommunications to medical diagnostics to environmental monitoring.
As more research develops, Tittl and his collaborators hope to investigate other potential avenues in this space. “Essentially, we’ve developed ultrathin resonators that capture light very efficiently so that we can use it,” emphasized Sortino. However, the continuing research is oriented towards enhancing their properties and functionalities as such components. They work incredibly hard to serve the needs of our dynamic and constantly changing tech landscape.