The combination of sensitivity, transparency and patternability offered by phenyl-bridged polysilsesquioxanes provides numerous possibilities for the fabrication of innovative optical sensors using straightforward processes.

The system, which is reported in the journal Nanotechnology, is composed of a thin metal slab waveguide in which the surface plasmon polaritons (SPPs) at the two metal-dielectric interfaces superpose. This results in two physical coupled modes: the long-range SPPs (LRSPPs) and the short-range SPPs (SRSPPs).

The sensor performance was tested against the detection of 30 ppm xylene by monitoring the influence of the target gas on the SPPs modes. A reversible red-shift of the reflectance dips of both LR and SRSPP resonances was observed and correlated to the interaction with the analyte. An enhancement in sensitivity associated with the rotation of the grating grooves with respect to the scattering plane was verified within experimental errors.

Additional details can be found in the journal Nanotechnology.