An alternative to plasmonics ?

Surface plasmon-polaritons propagating on metal thin films have found numerous applications in biosensing. While the spatial localization of the mode along one direction provides definite advantages, the high losses caused by absorption in the metal limit the utilization of such modes for signal processing.

In a collaboration with the Polytecnico de Torino and colleagues in the Institut de Microtechnique at EPFL, we present here a direct evidence of Bloch surface waves (BSWs) waveguiding on ultrathin polymeric ridges, supported by near-field measurements. We demonstrate that near-infrared BSWs sustained by a silicon-based multilayer can be locally coupled and guided through dielectric ridges of nanometric thickness with low propagation losses. Using a conventional prism-based configuration, we demonstrate a wavelength-selective BSW coupling inside and outside the ridge. Such a result can open interesting opportunities in surface wave-mediated sensing applications, where light could be selectively coupled in specific regions defined by nanometric reliefs. A slightly focused linearly polarized beam illuminates the multilayer and the waeguide ridge according to the Kretschmann configuration. Once the TE-polarization is set, a selective coupling of BSW inside or outside the ridge can be obtained depending on the radiation wavelength and the angle of incidence. The fibered SNOM tip raster scans the guide and the multilayer top surface.

Check the corresponding publication: PDF External link: doi: 10.1021/nl100481q