A Nanoporous Silicon 1-D Photonic Band Gap Microcavity as a Selective Optical Sensor

摘要

A nanoporous silicon (pSi) one dimensional photonic band gap (1-D PBG) with a microcavity was prepared for selective sensing in the optical regime. The cavity resonance of the localized mode was tuned by the thickness of the defect layer, and this localization led to a selective reflectance. The band gap was demonstrated in the optical regime (450-600 nm) and the microcavity was centered at 588 nm when illuminated with incident light to the normal. Crystal Violet dye (absorption at 593 nm) was adsorbed into the structure due to its absorption match with the microcavity (593 nm). Uv-vis spectroscopy was used to characterize the sensitivity of the dye. Since there was a decrease in the reflectance intensity at the microcavity center, the intensity could be used to detect the analyte type and its concentration. In addition, there is a high selectivity for the wavelength of interest. The new feature of this sensor is that an absorbing dye was adsorbed into the structure to match the cavity in the PBG structure in the optical regime.