Design, Ultrastructure and Dynamics of Nonlinear Optical Interactions in Polymeric Thin Films
Abstract
This program covered microscopic theory of optical nonlinearity, design and synthesis of novel structures, materials processing for guided waves, measurements of optical nonlinearities and study of device processes. Both classical anharmonic oscillator approach as well as ab-initio calculations to understand the microscopic nature of optical nonlinearities in organic structures had been described. The ultimate goal is to understand the structure- property relationship so that one may be able to predict structures with enhanced optical nonlinearities. The focus of our work has been on third-order optical nonlinearity. We developed a simple model of coupled locally an harmonic oscillators which can be used to describe the optical nonlinearities in conjugated organic monomeric, oligomeric and polymeric structures. We showed that the method can very readily be used to explain the dependence of the band gap, the polarizability, alpha, and the second hyperpolarizability, gamma, as a function of the number of repeat units for the oligomers of thiopene and benzen. The results predicted by the coupled anharmonic oscillator model are in good agreement with those of the experimental studies of thiophene and benzene oligomers recently reported by our group. In addition, the predicted power dependences of orientationally averaged (alpha) and (gamma) on the number of repeat units were compared with those predicted by a free electron model, PPP methods, sum-over-states method and ab initio calculations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 04, 1990
- Accession Number
- ADA228876
Entities
People
- Paras Nath Prasad
Organizations
- University at Buffalo