| This dissertation presents the results of a series of electroabsorption measurements on the following conjugated polymers: trans-polyacetylene (unoriented and oriented), poly(3-hexylthiophene), poly(p-phenylene vinylene) and poly(2,5-dimethoxy-p-phenylene vinylene). The data are used to determine various nonlinear optical terms for these materials, including the electric field induced changes in the complex index of refraction and the complex dielectric function. The third order nonlinear susceptibility, {dollar}chi sp{lcub}(3){rcub}{dollar}, and the electrooptic Kerr coefficient, K, are also evaluated as an aid in determining the usefulness of these materials in electrooptic device technology. Of the materials studied, the largest electroabsorption response is seen with trans-polyacetylene. The electroabsorption signal occurs near the band edge in each case, with a lineshape which may be approximated by a second derivative (with respect to photon energy) of the unperturbed absorption curve. Anisotropy of the electroabsorption response is obtained by varying the polarization of the incident light with respect to the axis defined by the applied electric field. Temperature, field strength, modulation frequency and light intensity dependences are also reported. The experimental techniques and methods of analysis are described in detail, along with suggestions for future electroabsorption and electroreflectance measurements on organic conducting polymers. |
