Abstract: The preparation of objects, in particular optical components and/or devices, is described using, as precursors of optical materials, amorphous monolithic aerogels for high-precision mechanical machining.

Abstract: A method for preparing inorganic oxide-based materials of spherical form with substantially monomodal distribution, consisting of forming a sol of at least one of the inorganic oxides of interest, adding to said sol a solvent immiscible with the sol, finely dispersing the obtained two-phase mixture into a dispersion of particles of equal diameter, growing said particles by limited coalescence to the desired diameter, gelling said mixture by adding a second solvent containing a gelling agent, and removing the solvent.

Abstract: The present invention provides a bistable optical device in which the active medium is a polymer material of thermo-optical effect inserted into a cavity resonator, preferably a FABRY-PEROT resonance cavity, in said cavity the polymer material transmitting and reflecting an incident light wave with bistable values and values variable according to its thermal state. This latter is varied by the absorption of a fraction of the incident light wave, which transfers heat to the polymer material to generate therein an increase in the transmission of the incident light and a variable refractive index in response to the increase in its temperature, to thus provide a positive response effect which enables the device of the present invention to vary between two bistable states.

Abstract: A method for preparing inorganic oxide-based materials of spherical form with substantially monomodal distribution, consisting of forming a sol of at least one of the inorganic oxides of interest, adding to said sol a solvent immiscible with the sol, finely dispersing the obtained two-phase mixture into a dispersion of particles of equal diameter, growing said particles by limited coalescence to the desired diameter, gelling said mixture by adding a second solvent containing a gelling agent, and removing the solvent.

Abstract: A nonlinear all-optical switching device including a waveguide of an organic conjugated material which forms a nonlinear optical medium. The nonlinear material has an index of refraction which is a function of the local intensity of light. Light beams passing through the waveguide intersect and interact causing diffraction into secondary beams. The intensity of the diffracted beams is a function of the intensity and frequency of the intersecting light beams. The nonlinear material can respond extremely fast and provide a bandwidth exceeding 500 GHz.

Abstract: A supported catalyst for the polymerization and copolymerization of olefinically unsaturated compounds is described, comprising an organometallic compound of aluminium and a second component obtained by bringing a titanium, vanadium or chromium compound, at least one compound of a second metal chosen from V, Al, Zr, Hf, Mo and Nd and optionally a magnesium compound into contact with a porous support consisting of microbeads of aerogels of one or more inorganic oxides distinguished by low density, high porosity and the fact that at least 90% of the pores have a diameter lying within a very narrow range of values. The process for the polymerization or copolymerization of olefinically unsaturated compounds based on the use of said catalyst is also described.