Porous silicon microcavities as optical chemical sensors

The optical properties of porous silicon microcavities are strongly depende nt on the environment. For highly luminescent samples, both the luminescenc e intensity and the peak position are affected by organic substances, givin g the possibility to obtain dual-parameter optical sensors. While the peak position depends on the organic compound refractive index, luminescence int ensity depends on its low-frequency dielectric constant. This allows the di scrimination between different organic substances. This sensor is particula rly interesting for solvents with low dielectric constant, where the respon se of electrical sensors is very weak. (C) 2000 American Institute of Physi cs. [S0003-6951(00)00718-X].