Small-Molecule Vapor-Deposited Materials for Integrated Nonlinear Optics

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Non-technical Description: Nonlinear optical materials enable the interaction between multiple photons, allowing light signals to control other light signals. Such capabilities are important for continuous developments in optical computing and in optical telecommunication networks such as those that today transmit everything from TV channels to the Internet. This research project aims at studying and developing a new fundamental paradigm that consists in using small organic molecules to build high-quality "plastic" nonlinear optical materials that can then be used with current and future technologies to provide important new all-optical data-processing capabilities at ultrafast speeds. The interdisciplinary nature of the research and its vertically integrated approach (from molecules to materials to devices) provide a varied training ground for the education of undergraduate and graduate students, who learn to use modern laser systems and to control (in wavelength and in time) short optical pulses, while at the same time being exposed to chemistry on one side and engineering on the other.Technical Description: The project aims at advancing the understanding of fundamental nonlinear optical properties and how they translate from molecules to the solid-state, and at creating flexible organic nonlinear optical materials by vapor deposition of optimized molecules into dense supramolecular assemblies with a high optical quality. The research focuses on small molecules where donor-acceptor substitution leads to lower excited state energies and higher third-order polarizabilities, and it exploits the high molecular densities achieved in single-component assemblies to obtain off-resonant third-order nonlinearities in the final bulk materials that are at least three orders of magnitude larger than silica glass. The properties of the molecules, the resulting evaporated materials, and their relationships are studied with a range of nonlinear optical laser spectroscopy techniques and thin-film characterization methods. Optimized molecular designs lead to evaporated materials with a high, glass-like optical quality that can be combined with existing integrated optics technologies, such as silicon photonics, to add active components for applications such as all-optical switching.