Second Harmonic Generation

Abstract approved: Dr. Allen Wasserman This study investigates nonlinear optical properties of matter. Nonlinear optical effects have found a wide field of applications such as the extension of the operation range of lasers to higher frequencies, material probes and optical image processing. A brief introduction to the most common nonlinear optical phenomena is given and the currently used methods for the calculation of nonlinear optical susceptibilities are reviewed and their advantages and shortcomings are discussed. A new diagrammatical approach is proposed and shown to yield the same results as the current methods at zero temperature. The method is then applied to Polyacetylene, which is modeled as a linear chain whose two degenerate ground states are divided by a domain wall called a soliton. The Green's Functions for this system are used to obtain expressions which are evaluted numerically to yield the second order nonlinear susceptibility over a wide range of input frequencies