Determination of the Refractive Index Profile of a Polymer Waveguide by Photobleaching

The shrinkage effect of polymer films, which was demonstrated in our photobleaching experiment, can be fitted approximately by an exponentially decaying function. After taking the shrinkage effect into account, the index profile of the polymer waveguide was determined to be a Fermi function with the help of the m-line method and the exact transfer matrix theory.