The effect of microstructure upon light-emitting polymer waveguides

Summary form only given. Microcavities are currently being employed to enhance the performance of optical sources, such as the light-emitting diode. Owing to the high refractive index of many emissive materials, much of the radiation is trapped in the form of waveguide modes and subsequently lost. If this loss could be overcome, the efficiency of light-emitting devices might be improved. One way of extracting this energy is to introduce periodic microstructure in the plane of the microcavity. Waveguide modes may then Bragg-scatter off the periodic microstructure, to emerge as useful radiation. We present results demonstrating that suitable periodic microstructure may indeed be used to Bragg-scatter waveguided light out of such devices. In order to understand the mechanisms involved, it is extremely valuable to know how the microstructure affects the dispersion of the microcavity modes. To this end, we have undertaken a detailed set of measurements that allow us to look at the changes produced in the dispersion diagram as a consequence of the periodic microstructure.