Two areas of research activity will be pursued: (1) The design and synthesis of new polymeric electroactive materials relevant to electro-optic modulation, optical amplification, and sensor protection; and (2) the development and utilization of new forms of spectroscopy that permit improved characterization of material electroactivity. The first area of research includes the development of improved theory capable of predicting the supramolecular assembly and organization of electroactive polymers, the use of such theoretical guidance to synthesize chromophore-containing polymer materials that can, with appropriate processing (e.g., electric field poling near the polymer glass transition temperature), produce materials exhibiting large electro-optic activity, the development of new lattice hardening chemical reactions to lock-in processing-induced electro-optic activity, and the use of such polymeric materials for the fabrication of integrated "opto-chips", i.e., integrating VLSI semiconductor electronics with polymeric electro-optic modulator circuitry. Control of supramolecular (nanoscale) architecture will also be extended to the development of other technologically important polymeric systems including stable polymer materials incorporating electroactive dendrimer materials. Again, new theoretical design concepts will be applied to develop materials with controlled nanoscale molecular organization and controlled intermolecular electronic interactions. Polymer processing will be used to achieve final material properties necessary for practical (ultimately commercial) implementation of materials produced. In the second area of research focus, particular attention will be given to the development of new techniques of femtosecond spectroscopy that are particularly relevant for the characterization of electroactive polymeric materials. These include techniques for improved measurement of "instantaneous" optical nonlinearities necessary for understanding both the magnitude of various macroscopic optical nonlinearities and necessary for understanding materials response times. Particularly, focus will be given to development of the new technique of frequency-agile, near-degenerate, multiple-wave-mixing spectroscopy and exploitation of the "signal-lattice" detection scheme that permits simultaneous measurement of the real and imaginary components of various optical nonlinearities. Information from these techniques will be used to evaluate the appropriateness of new materials for various practical photonic applications. Studies will also define photochemical stability of molecules and will provide fundamental insight into subtleties of excited energy transfer relevant to processes such as light harvesting. %%% Previous NSF supported research has resulted in new state-of-the-art telecommunication and signal processing polymeric electro-optic modulator (PEOM) devices characterized by bandwidths of greater than 100 GHz, drive voltage requirements of less than 5 volts (digital voltage levels), and total insertion losses on the order of 4dB. Such modulators are likely to be critical components of future information superhighways as well as being used for signal detection, flat panel displays, CATV, radar applications, guidance systems, information processing, and signal routing in a variety of optical networks. Polymeric modulators are currently being evaluated as components of next generation high bandwidth internet communication. In like manner, improved fiber optical amplification and white light harvesting materials have been developed that promise important improvement in fiber optic communication. Very fundamental theoretical understanding resulting from this work will likely have far ranging impact on the scientific understanding of solid and liquid state materials and will likely provide important guidance for the synthesis of materials with architectural control at the nanometer level and special properties derivative from such organization. ***
