The research objective of this Faculty Early Career Development (CAREER) project is to generate the fundamental manufacturing science necessary to economically create metasurfaces at large scales. Metasurfaces are microscale-to-nanoscale structured surfaces that are engineered to produce electromagnetic properties beyond what is available in nature, and have many potential fundamental applications applications including enhancing heat transfer, increasing the detection limits of gas sensors, and ultrathin optical devices. Using conventional lithography-based approaches, metasurfaces are very expensive, and as a result are generally produced only at the centimeter scale for laboratory demonstrations. This project will create new manufacturing techniques emphasizing Microsphere Photolithography (MPL), which uses self-assembled microspheres to focus photonic jets into a photoresist layer, generating indentations in the surface. The spheres are subsequently removed to reveal the pattern. The project will rigorously determine the process-structure-metasurface performance relationships for MPL and establish pathways to scale-up to mass production, including roll-to-roll printing and electroforming. The integrated education program will engage students by allowing them to design/build/test devices that demonstrate the improved performance associated with sub-micron structures but at scales that they can handle. A particular emphasis is placed on increasing the involvement of first generation, rural, college students and underrepresented minorities in engineering as well as developing a trained workforce for the rapidly emerging advanced optics sector.
This research will create a framework for manufacturing using Microsphere Photolithography (MPL). The project entails four research objectives (1) generation of complex metasurfaces using MPL, (2) improving the yield of the process through improved self-assembly and metrology, (3) scaling the process using reusable masks including a roll-to-roll configuration and (4) integrating the MPL approach with electrodeposition The research will also generate accurate physics based models for the process, including the effects of normal and off-axis illumination. This will facilitate better metasurface performance and address the critical problem of scalable low-cost manufacturing of micro-to-nanostructures in the context of representative test-beds including enhanced radiative cooling of buildings, and planar optics. The research outcomes will be new knowledge about the material/photonic jet interaction, significantly improving the manufacturing platform for the fabrication of metasurfaces and similar structures.