3-D Additive Multiscale Manufacturing Using Near-Field Ultrafast Laser Processing

The proposed work addresses the development and characterization of an innovative 3-D additive manufacturing process capable of producing uniform, multiscale metal and polymer features on non-traditional surfaces using a combination of near-field and ultrafast laser processing. The ability to modify surfaces by directly adding 2 and 3-D objects with high throughput, resolution, and uniformity has become increasingly important as new technologies continue to push the limits of feature size, density, and engineered functionality. Through a synergistic transatlantic collaboration that leverages the strength and expertise of the applicant and the research group of Prof. M. Schmidt at the Friedrich-Alexander Universität Erlangen- Nürnberg (FAU), we propose a comprehensive and multidisciplinary project that combines the patterning resolution and scaling benefits of optical trap assisted nanopatterning (OTAN) with the 3-D additive capabilities of multiphoton processing (MP). In doing so, we leverage the strengths of each technique to overcome their individual limitations in order to leapfrog current technology in additive manufacturing. Through the development of this new rapidprototyping approach, we seek to understand the relationship among processing conditions, materials structures and properties by addressing fundamental scientific and technological questions through process design, experimentation, and numerical modeling. OTAN is a new all-optical direct-write patterning method that uses opticallytrapped microbeads as near-field objectives, which enable sub-wavelength focusing of a second laser. Through the use of advanced optical manipulation technology, this technique allows for the fabrication of surface features over rough or textured surfaces with high resolution, uniformity and reproducibility. Whereas OTAN excels in 2-D surface modifications, MP has emerged as the leader for the production of small-scale user-defined 3-D structures within a volume. However, for fabricating integrated 3-D functional materials, it is critical to optimize the size and shape of the printed voxel and the possibilities to do so with traditional far-field optical elements residing outside the reaction chamber are limited. The merging of OTAN, developed in our group at PU, with femtosecond laser manufacturing and MP, as exemplified and perfected by our colleagues at FAU, introduces an entirely new dimension in the field of 3-D additive surface engineering by applying near-field beam shaping and concentrating capabilities to the MP fabrication process through an easily implemented, robust, and scalable approach. Furthermore, this team is uniquely qualified to undertake this important research effort, opening the door to the manufacture of novel devices based on multiscale architectures with nanometer resolution for diverse fields ranging from metamaterials and optoelectronics, to biological and microfluidic systems. In this study we would take a multipronged approach relying on common objectives and close exchange and interactions. The first phase will begin with initial process modeling of the system and demonstrating proof-of-principle for the OTAN-MP process using standard polymer and metal chemistries. In the second phase, we introduce detailed experimental characterization and correlation of structures, properties and processing, through standard optical, electrical, and physical measurements. In addition, the second phase will focus on developing fundamental understanding of the underlying optical and physical interactions through analytic and numerical modeling. Finally, we build upon the knowledge gained in the initial stages to begin modeling and developing a parallel version of the OTAN-MP enabling high throughput with an eye toward future commercial and industrial uses.