Biopolymeric, Non-Linear-Optical Materials Produced in Microgrvity Using Electric Field Alignment

Defect-free crystals which exhibit optical non-linearities are of great interest. Recent development of polymers with large second and third order nonlinear effects has generated interest in the potential of polymeric non-linear optical materials (NLOM). The ideal NLOM would have a very large nonlinear response, extremely low switching thresholds and rapid switching times, as well as amenability to defect-free fabrication. Crystals grown in space have been shown to be of higher quality than "earth-grown" crystals because more defect-free specimens are obtained in the absence of gravity-fueled convection. Defect-free organic crystals are of particular interest because they can exhibit high optical non-linearities. However, as these are molecular crystals, they tend to be brittle and cannot be as easily fabricated into thin films or fibers as can polymer analogs. Little attention, however, has been paid to the growth of high-quality macromolecular polymeric films in space. Polymers having a controlled supermolecular structure and morphology could be even more promising candidates as NLOM. A previous NASA project projected the feasibility of processing biopolymers, materials with known supramolecular structure, in an electric field under microgravity conditions in order to optimize optical non-linearity. The proposed work will identify the particular importance of understanding polymer processing conditions, particularly with respect to electrode and cell design.