Accession Number : ADP006440

Title :   Sol-Gel Nano-Porous Silica-Titania Thin Films With Liquid Fill for Optical Interferometric sensors,

Corporate Author : IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (UNITED KINGDOM) DEPT OF ELECT RICAL ENGINEERING

Personal Author(s) : Judeinstein, P. ; Livage, J.

Report Date : MAR 1992

Pagination or Media Count : 12

Abstract : The production of thin films whose refractive index is measure specific, for use in an interferometric fiber optic chemical sensor, is discussed. The problem of making such coatings has been tackled by a system we have termed the guest-host approach, in which an active liquid whose index varies with measure, is contained within a porous glass host of fixed index. Suitable porous silica-titania glass films have been produced via the sol-gel process. ne use of this system enables the index of the glass to be varied, so that the composite index of the liquid filled film can be tailored to that required by the optical system. The sol-gel method developed is based upon the hydrolysis and polymerisation of metal alkoxides, in an acidic aqueous/alcoholic solution. Thin film slab waveguides were deposited in order to measure the light scattering losses, which were found to be typically -ldB/cm. The porosity of films was studied using a new technique developed in which water adsorption isotherms are plotted using ellipsometry. The pore size was found to be very small of pore diameter in the nanometer range, and the total porosity -10%. Both of these factors were increased by the removal of residual organic material, using hydrogen peroxide. Finally the use of pH indicator dyes as a liquid fill is discussed, to produce a pH sensor.

Descriptors :   *FIBER OPTICS, *OPTICS, ADSORPTION, APPROACH, CHEMICALS, COATINGS, DIAMETERS, DYES, FIBERS, FILMS, GELS, GLASS, HYDROGEN, HYDROGEN PEROXIDE, HYDROLYSIS, INDEXES, INDICATORS, ISOTHERMS, LIGHT, LIGHT SCATTERING, LIQUIDS, LOSSES, MATERIALS, METALS, ORGANIC MATERIALS, PEROXIDES, POROSITY, POROUS MATERIALS, PRODUCTION, REFRACTIVE INDEX, REMOVAL, RESIDUALS, SCATTERING, THIN FILMS, WATER, WAVEGUIDES.

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE