Template-based Fabrication of Three-dimensional, Chiral Plasmonic Nanostructures

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Chirality describes the structural handedness of objects which are distinct from their own mirror images. Chirality is ubiquitous in nature and best known in looking at our own left and right hands. It is also found in many sugar molecules, amino acids and in larger proteins, nucleic acids and viruses, where chirality has a profound effect on function; for example chiral molecules behave differently in chemical reactions and in their interaction with polarized light. Inspired by natural chiral molecules, artificial chiral plasmonic nanostructures are explored to exploit their strong light interaction and realize 'giant' optical responses for applications including biosensing, light emission, and light manipulation. The realization of chiral plasmonic nanostructures requires plasmonic materials to be shaped into complex, subwavelength, three-dimensional architectures. However, it is not trivial to fabricate high densities of these nanostructures over the large areas required. This award will unite top-down fabrication and bottom-up assembly to realize chiral plasmonic nanostructures that have strong, polarization-dependent optical properties. By exploiting the disparate physical properties of bulk and nanocrystalline materials, chiral materials that are responsive to optical and magnetic stimuli will be created. The team will utilize the simplicity of these fabrication technologies to design a new optical device fabrication lab to make the field accessible to K-12 and undergraduate students participating in science festivals, camps, and formal curricula. The team will also share career experiences to encourage women to pursue careers in science and engineering. Optical metamaterials enable unprecedented control of light by engineering the size, shape, and physical properties of matter, artificially structured from plasmonic and non-plasmonic building-blocks with nanometer scale precision. Among them, chiral plasmonic metamaterials combine strong light-matter interactions with the unique polarization selectivity created by their structural handedness. This award aims to advance the nanoscale manufacturing of large-area, multi-functional, three-dimensional, chiral plasmonic nanostructures by exploiting size- and shape-engineered templates defined by nanoimprint lithography and the different deposition processes and properties of bulk and nanocrystal thin films. By combining angle-selective, shadow evaporation of bulk metal thin films with the isotropic deposition of colloidal nanocrystal thin films, hierarchal, chiral nanostructures will be created. Taking advantage of the distinct chemical and structural properties of bulk and nanocrystal thin films, stress will be exploited to drive buckling of bulk metal/nanocrystal nanostructures and thereby turn planar two-dimensional into three-dimensional, chiral nanostructures. By integrating different bulk and nanocrystal materials, strong polarization-dependent and optically and magnetically responsive chiral materials will be realized.