Fiber optic networks –must be fast-acting –must integrate into fiber systems –must operate at infrared wavelengths Eye protection –scope sights –binoculars –must operate at both visible and infrared wavelengths Applications Optical Limiters Acquisition of spectroscopic and computational instruments for undergraduate education and research in nonlinear optical materials James Butler, Pacific University, DMR The optical limiters in this investigation use nonlinear absorbers. The percentage of light that these materials absorb increases with the intensity of the incident light. Dim Light In Dim Light Out Bright Light In Dim Light Out Optical limiters are devices that can be used to control the brightness of the light that reaches a sensitive optical component

Optical Limiting in Capillary Waveguides at Infrared Wavelengths Simulations and inset images are consistent with the energy being confined to a small region within the core leading to an enhanced optical limiting response Simulations indicate that two-photon absorption plays a significant role in optical limiting for OsPZnOs in infrared Silica capillaries with 10 μm internal diameter filled with 0.2mM solution of OsPZnOs dissolved in DMSO Inset shows energy distribution (false color) within the capillary core (white circle) * Experiments are continuing at Pacific University with equipment purchased from this grant The data shown here was taken by the PI and collaborators at the Naval Research Laboratory (NRL) in the summer of 2006.* The modeling of the data was done by undergraduates at Pacific University in the summer of nm Nonlinear Transmission Data1050nm Nonlinear Transmission Data = data = simulation James Butler, Pacific University, DMR

Molecular Modeling Results Undergraduate student, Joshua D. King, completed his senior thesis in chemistry titled, “Investigation of the electronic Spectroscopic Properties of Phthalocyanines and Related Dye Molecules Using Time-Dependent Density Functional Theory”. SCIENTIFIC PROGRESS Results to Date A computational study of the effect of macrocycle size and symmetry was undertaken for a series of Magnesium Phthalo- and Naphthalo- cyanines Simulated electronic absorption spectra for ground singlet, S0, first excited singlet, S1, and first excited Triplet states were calculated and are shown to the right. Ground state MO density is observed to be a  orbital with electron density distributed equally on the thalocyanine plane. Excited singlet states are observed to concentrate MO density on a single axis of the molecule. When the two molecular axes are of the same length, the LUMO orbitals are degenerate. However, counter to expectations, for molecules with unequal length in the axes of the macrocycle plane, the lower energy virtual orbital concentrates MO density on the short axis. This is the origin of splitting in the ground state spectra. SOFTWARE IMPLEMENTATION Developed modeling protocol using the TD-DFT implementation in the ADF software package The ADF implementation of TD-DFT with Slater type orbitals was found to be superior in predicting electronic spectra of both ground and excited states. The software also runs Parallel on our Power Macintosh, greatly improving computation times. Software License supported by internal Faculty Development Grant from Pacific University to co-Pi Johnson James Butler, Pacific University, DMR