Coupling of surface waves in highly defined one-dimensional porous silicon photonic crystals for gas sensing applications

We describe the use of one-dimensional porous silicon p-Si photonic crystals for guiding TE-polarized surface electromagnetic waves SEWs. Although bulk and interface roughnesses might deteriorate the optical response of photonic structures, we observed reflection spectra presenting narrow 6 nm reflectivity anomalies associated with SEWs. In analogy with surface plasmons, SEWs are strongly sensitive to surface modifications. As a proof of principle for a sensor, we provide a direct real-time monitoring of the reversible interactions of organic vapors with the p-Si multilayer.We highlight the higher sensitivity of the SEW-based detection scheme as compared to a method exploiting perturbations of waveguide modes. © 2007 American Institute of Physics. DOI: 10.1063/1.2824387