At&t Bell Laboratories

Lucent Technologies Inc.

Fitel USA Corporation

Thomas Michael Putvinski

Howard Edan Katz

Marcia Lea Schilling

William Larry Wilson

Suhas Dattatreya Bhandarkar

Christopher E Chidsey

Geoffrey R Scheller

Edwin Arthur Chandross

Frank J McNally

A sol-gel process for fabricating bulk, germanium-doped silica bodies useful for a variety of applications, including core rods, substrate tubes, immediate overcladding, pumped fiber lasers, and planar waveguides, is provided. The process involves the steps of providing a dispersion of silica particles in an aqueous quaternary ammonium germanate solution&mdash;typically tetramethylammonium germanate, gelling the dispersion to provide a gel body, and drying, heat treating, and sintering the body to provide the germanium-doped silica glass.

Sol-gel process for fabricating germanium-doped silica article

A silica body useful for forming an optical fiber preform exhibits an ultimate strength of at least 20 MPa at 10 wt. % water loss. The body attains this strength, it is believed, by precipitation of silica at the contact sites of adjacent silica particles, thereby forming neck regions. The resultant network provides the strength to the gel body, such that the body is capable of being dried under more severe conditions than a gel body formed by previous sol-gel methods and is also more robust toward handling. The controlled precipitation is attained by inducing gelation and initiating drying at a pH of about 10.5 or higher, at which silica remains highly soluble. By gelling and drying at this pH level, the solubilized silica appears to precipitate in a controlled manner at the point of contact of adjacent silica particles, since such sites are the minimum free energy sites for precipitation.

Method for forming article using sol-gel processing

This invention embodies an optical medium which consists of polar, multi-monomolecular layers of organic dye molecules with a net polar orientation, considerable second order optical nonlinearity, and excellent thermal stability. The medium is prepared by repeated sequential depositions on a surface of multivalent metal ions, e.g. Zr.sup.4+, and organic dyes terminated with an acidic functionality, e.g. a phosphonic acid, followed by activation of the surface for the next deposition sequence. The monolayers are deposited in the form of a multilayer film containing up to 1000 or more monolayers. The monolayers are deposited from liquid solutions; therefore they may be deposited on substrates having diverse topography and configurations. Second harmonic generation (SHG) analysis establishes that the multilayers have uniform polar order which does not decrease with increasing numbers of monolayers in the film. As determined by SHG, the inorganic interlayers impart orientational stability to the dye molecules up to 150.degree. C. and higher. The optical medium is useful in electrooptical or optical parametric devices comprising an optically nonlinear element and means for providing an optical input to and output from said element wherein said element comprises the nonlinear optical medium supported on a suitable base. When said device is employed in an electrooptic mode, it includes means for applying an electric field and/or optical input to said element for altering an optical property thereof.

Stable polar optically nonlinear multilayer films and devices using the

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Scotch Plains, NJ, United States of America

Thomas Michael Putvinski