The Theoretical Study Of Nonlinear Optical Properties Of Organic Molecular Materials

In recent years, as the birth of laser and the rapid development of laser technology, nonlinear optics becomes an important embranchment of the field of modern optics, in which the interaction of intense laser with matter is studied. At the same time, it has become an important project to find new nonlinear optical materials, due to their wide use and attractive application foreground, for example, in laser frequency doubling, laser frequency mixing, parametric amplification and oscillation, integrated optics, optical communication, beam steering, beam distortion removing, image multiplication and transformation, optical limiting and threshold monitoring, complete optical connecting, optical computer and other fields.Much emphasis has been put on organic nonlinear optical materials because they have many advantages, such as large nonlinear optical coefficient, wide response wave band, good flexibility, high optical damage threshold, low cost, and easy combination and modification. The thesis studies the linear and nonlinear optical properties of newly synthesized organic molecules utilizing many theoretical and computational approaches, which are on the base of the ab initio level. The relation of the molecular structures and properties is discussed, and the solvent effect on the molecular optical properties is investigated as well. The main contents and results are represented as follows.The nonlinear optical properties of one-dimension nonsymmetrical D-Ï€-A charge-transfer (CT) molecule VPDB in gas phase and different solvents have been studied on the base of time dependent density functional theory. First, the molecular geometry in gas phase is optimized on the base of density functional theory; the polarized continuum model is used when studying the solvent effect, and the geometry optimization of the molecule in each solvent is redone by using the polarized continuum model (PCM) on the base of density functional theory. Then the nonlinear optical properties of VPDB molecule in gas phase and different solvents are studied using few-state model approach on the base of time dependent...