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 (≲6nm) 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.