Long range surface polaritons supported by lossy thin films

We demonstrate experimentally that strongly absorbing chalcogenide thin films can support long range surface polaritons. Moreover, the possibility to change the phase of this material allows us to investigate the influence of the permittivity of the thin film on the surface modes. We demonstrate the relative insensitivity of these modes to the permittivity of the thin film. Extending the range of materials that support long range surface polaritons to strongly absorbing layers opens new possibilities for applications that were thought to be limited to weakly absorbing media.