Novel liquid sensor based on porous silicon optical waveguides

The introduction of solvents into the pores of optical waveguides formed using porous silicon is shown to dramatically reduce the interfacial scattering loss of the waveguides (by as much as 34-dB cm/sup -1/ in one example), in a reversible manner. The degree of loss reduction is dependent on the type of solvent introduced. These observations, combined with the fact that a substantial portion of the guided-mode field interacts with the solvent introduced into the pores, indicate that an enhanced sensitivity for sensor applications may be achievable across a broad range of operational wavelengths.