Glass-based Photonic Crystals: from Fabrication to applications

We report on the fabrication and on the assessment of the properties of two glass-based photonic crystals (PhCs) obtained using alternative approaches such as rf-sputtering and sol-gel techniques. (i) By means of rf-sputtering a one-dimensional dielectric photonic crystal constituted by an Er3+-doped SiO2 active layer inserted between two Bragg reflectors consisting of 10 pairs of SiO2/TiO2 layers has been realized. Near infrared transmittance spectra evidenced the presence of a stop band from 1500 to 2000 nm with a cavity resonance centered at 1749 nm. Intensity enhancement and narrowing of the emission band of Er3+ ions, due to the cavity effect have been observed and a cavity quality factor of 890 has been achieved. (ii) Through chemical route a 3D colloidal crystal based on polystyrene (PS) nanoparticles (NPs) embedded in elastomeric matrix has been realized. In the specific has been shown that the structure can produce a variation of its color applying different organic solvents that can be also easily observed by the naked eye. Optical measurements have evidenced a red shift of the diffraction peak as a function of the solvents applied. This feature has been exploited in order to create a sensitive material showing high sensitivity and reversibility of the signal change.