Nonlinear optical (NLO) polymers are promising new materials for use in devices such as optical modulators, wave-guide harmonic generators, and integrated optical switches. Devices such as these will be required in future photonic based communication, computing, and sensor systems. In addition, electro-optic (EO) polymers are finding use as sources for the generation of terahertz (THz) radiation and as sensors for the detection of THz radiation. Applications of THz radiation include imaging in the medical and security fields, package inspection and tablet evaluation in the pharmaceutical industry, chemical sensing for atmospheric monitoring, and sub-picosecond far-IR spectroscopy of dielectric materials, particularly those materials useful in the fabrication of solar cells. We also use NLO techniques such as second harmonic generation (SHG) and electro-optic (EO) modulation to probe the local environment and dynamics in macromolecular materials intended for use in photonic devices. Relaxation of the second order optical susceptibility is studied as a function of temperature and pressure. Activation energies and volumes associated with the relaxations are determined and used to identify the mechanism for the re-orientation of the NLO moiety. These structure-property results are used by chemists to synthesize new more stable materials. We have recently begun to apply molecular modeling techniques to study polymer relaxations, NLO properties of polymers, and to simulate the far-IR spectra of NLO polymers. We have developed fully atomistic models to simulate electric field poling of guest-host and dendrimer NLO composites. We are also involved in the development of atomistic models that will allow us to predict the far-IR spectrum of EO polymers. The other major thrust of the laboratory is involved with photorefractive, photochromic, and photo-polymerizable polymers. These new materials are interesting because of their potential application in optical signal processing, holographic storage, all optical computing, and wavefront correction. We currently measure the photoconductivity, electro-optic coefficient, diffraction efficiency, and photorefractive two beam coupling gain in a variety of these new materials. In addition we are exploring guided wave applications in these materials.