Effect of the alkali vs iron ratio on glass transition temperature and vibrational properties of synthetic basalt-like glasses.

Volcanic eruptions generate huge amounts of material with a wide range of compositions and therefore different physicochemical properties. We present a combined Raman and calorimetric study carried out on four synthetic basaltic glasses with different alkali vs iron ratio which spans the typical compositions of basalts on Earth. Differential scanning calorimetry shows that changes of this ratio modify the glass transition interval whereas Raman spectra allow to gain insight about the structure of the glass in the microscopic and macroscopic range.

Porous Si Microparticles Infiltrated with Magnetic Nanospheres.

Porous silicon (pSi) microparticles obtained by porosification of crystalline silicon wafers have unique optical properties that, together with biodegradability, biocompatibility and absence of immunogenicity, are fundamental characteristics to candidate them as tracers in optical imaging techniques and as drug carriers. In this work, we focus on the possibility to track down the pSi microparticles also by MRI (magnetic resonance imaging), thus realizing a comprehensive tool for theranostic applications, i.e.

Optical Study of Diamine Coupling on Carboxyl-Functionalized Mesoporous Silicon.

A functionalization strategy, consisting of a silylation reaction by acrylic acid followed by diamine coupling, preserves and stabilizes the photoluminescence (PL) of porous silicon (pSi) microparticles suspended in ethanol. We found that under the condition of efficient amine coupling, besides the orange emission typical of the native pSi, an emission band in the blue region appears. The investigation of the interaction between pSi and diamine shows that diamine quenches and shifts the orange band meanwhile it induces an increase of the intensity of the blue one.

Ultrafast all-optical switching in a silicon-nanocrystal-based silicon slot waveguide at telecom wavelengths.

We demonstrate experimentally all-optical switching on a silicon chip at telecom wavelengths. The switching device comprises a compact ring resonator formed by horizontal silicon slot waveguides filled with highly nonlinear silicon nanocrystals in silica. When pumping at power levels about 100 mW using 10 ps pulses, more than 50% modulation depth is observed at the switch output.

NanoSi low loss horizontal slot waveguides coupled to high Q ring resonators.

Si-based horizontal slot waveguides coupled to ring resonators have been fabricated and characterised. The central layer of the slot has been filled by Silicon nanocrystals (Si-nc) obtained by deposition of silicon rich silicon oxide and then thermal annealing. A comparison of various deposition and annealing parameters to form the Si-nc is performed.