Low-threshold polymeric distributed feedback lasers with metallic contacts

Optical losses in waveguides comprising metallic contacts are thought to be a major hurdle to the realization of organic laser diodes. We demonstrate here that careful tuning of the waveguide mode in flexible distributed feedback lasers can allow lasing action to occur in organic thin films in the presence of contacting electrodes with virtually no difference when compared to metal free devices. A metallic electrode is most suited as the bottom contact between the polymer and the substrate as it reduces mode leakage into the substrate and enhances modal gain. In contrast, a thin transparent electrode such as a metal oxide is preferable for the top electrode, where confinement is not a problem.