title: Smart optical sensors for chemical substances based on porous silicon technology.
abstract: A simple geometry optical sensor based on porous silicon technology is theoretically and experimentally studied. We expose some porous silicon optical microcavities with different porous structures to several substances of environmental interest: Very large red shifts in the single transmission peak in the reflectivity spectrum due to changes in the average refractive index are observed. The phenomenon can be ascribed to capillary condensation of vapor phases in the silicon pores. We numerically compute the peak shifts as a function of the liquid volume fraction condensed into the stack by using the Bruggeman theory. The results presented are promising for vapor and liquid detection and identification.
authors.affiliation: National Council of Research, Institute for Microelectronics and Microsystems, Via P. Castellino 111, 80131 Napoli, Italy. luca.destefano@imm.cnr.it
authors.forename: Luca
authors.initials: L
authors.lastname: De Stefano
authors.forename: Ivo
authors.initials: I
authors.lastname: Rendina
authors.forename: Luigi
authors.initials: L
authors.lastname: Moretti
authors.forename: Stefania
authors.initials: S
authors.lastname: Tundo
authors.forename: Andrea Mario
authors.initials: AM
authors.lastname: Rossi