Calculations of nonlinear waves in multilayer waveguides applied to polyalkylthiophenes, including linear and two-photon absorption

Abstract

The TE waves in a weakly nonlinear multilayer waveguide structure are studied theoretically; linear and two-photon absorption are included in the analysis. The nonlinear material is taken to be a polyalkylthiophene. The Jacobian function model is extended to the complex plane to describe the electric field in an absorbing structure, and the results are compared with those of perturbation theory. Both the Jacobian model and perturbation theory are found to be applicable in this problem; the Jacobian model fails only for strong two-photon absorption. A figure of merit is defined to describe the capability of nonlinear operation in various optical components, and its behavior is studied. The need to reduce linear absorption remarkably and to avoid two-photon absorption is established.