All-optical logic circuits based on photochromic building blocks using waveguide structures

• Applicants: Professor Dr. Jürgen Köhler; Professor Dr. Mukundan Thelakkat
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 448846348

The challenge to develop a device for signal transduction that runs on photons rather than on electrons requires materials that feature a high photochemical/photophysical stability, high fatigue resistance, a rapid response, and a thermally irreversible bistability as well as concatenation of optical input/output signals. All these properties need to be combined in one single system, which constitutes the main bottleneck towards all-optical logic circuits to date. Therefore, the main aim of the current project is to design, synthesize/assemble and spectroscopically characterize/quantify all-optical logic gates (AND, OR, NOR, NAND etc.) based on highly photostable photoswitchable dyads, triads, blends, and pendant polymers carrying differently substituted rylene dyes and photoswitchable molecules based on dithienylperfluorocyclopentenes (DCP) in thin films. These novel systems provide a platform for realising functions that are well known in the electronic world, yet where photons take over the role of the electrons. This requires adaptation of mutual excitation/emission energies of a collection of dyes and photoswitchable molecules and combinations thereof, which asks for an interdisciplinary research approach between chemistry and physics. Based on the experiences of our intensive joint work on photoswitchable systems, here we want to focus on fundamental studies towards all-optical logical gates. The realisation of this project is based on a chemistry part aimed at the synthesis of diverse photoswitchable systems involving both DCP and its emitting counterpart DCP-O4, their basic characterization using 1H-NMR, MALDI-ToF MS, UV-VIS absorption, TGA and DSC as well as cyclic voltammetry and the incorporation of the synthesized systems into films suitable for optical spectroscopy. The physics part, aims at assembling and spectroscopically characterizing all building blocks and the all-optical gates. This includes linear UV-VIS, and time-resolved spectroscopies for elucidating the energy transfer dynamics in films that accommodate combinations of dyes and photoswitches. Based on these results, optimized dye-switch combinations will be selected for realising all-optical logic gates using waveguide structures. Both parts of this interdisciplinary project are interwoven and bring in complementary skills required for the success of this project.

• DFG Programme: Research Grants