Photobleaching for optical waveguide formation in a guest–host polyimide

We present a methodology for determining the bleaching characteristics of dye-doped polymers. Our general phenomenological model predicts the absorption spectrum as well as the change in index of refraction as a function of wavelength for a bleached film. Determination of the parameters of the model requires only measurements of physical film characteristics (e.g., thickness, dye concentration), absorption features, and one index of refraction point. Our technique requires no detailed knowledge of the chemistry or physics of the polymer dye system. We have demonstrated the efficacy of our methodology by characterizing a guest-host system of 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4-H-pyran in Amoco 4212 polyimide. Based on our results, we speculate that it should be straightforward to generate model parameter values to characterize the bleaching of other dye-doped polymer systems.