Processing and Characterization of Nonlinear Optical Materials

Abstract

Abstract : New second order (x2) materials, third order (x3) materials and photorefractive materials were developed. A new design criterion was used to prepare a new class of x2 materials which would have both dipolar and octupolar contributions because of their multibranched 3 armed structures. We have developed new two-photon absorbing dyes (x3 materials) and their chemical conjugates for application in 3D microfabrication, 3D imaging, and optical power limiting. A major focus of our effort was careful characterization of the two-photon excited states and dynamics. For this we used femtosecond Z-scan and time-resolved pump probe experiments on the new and highly efficient multibranched fluorophore in which we discovered a new phenomenon of co-operative enhancement. We developed a two-photon fluorophores:chemotherapeutic drug conjugate and used it with two-photon laser-scanning microscopy to show the receptor-mediated entry of AN-152 into the cell cytoplasm and subsequently into the nucleus. These observations allowed a better understanding of the drug's therapeutic mechanism, which is a subject of ongoing research aimed at improving present methods for cancer therapy. Using a new approach of photosensitization with nanocrystallites of inorganic semiconductors, we have prepared photorefractive composites with good diffraction efficiency. Under this contract we have focused on developing an understanding of the basic process of photoconductivity, space charge field formation and temperature effects on kinetics in these nanocomposites.