At&t Bell Laboratories

Jeffrey B Bindell

James Thomas Cargo

Ronald J Holmes

Michael C Hughes

Oxides of tantalum and niobium are selectively etched using patterned silicon oxide deposited by a low-temperature chemical vapor deposition as a mask and a sulfate flux to selectively remove exposed portions of the tantalum or niobium oxide substrate.

Lithium niobate etchant

A proton-exchange method of forming optical waveguides within a lithium-based optical substrate is disclosed which utilizes sulfuric acid as the proton source. The substrate is masked to expose the areas desired to be transformed into waveguiding regions and immersed in a heated sulfuric acid bath for a period of time sufficient to provide the exchange between the protons in the acid and the lithium in the substrate. The presence of the protons in the substrate results in increasing the extraordinary refractive index .DELTA.n.sub.e in the unmasked area so that optical guiding may be accomplished. Upon removal of the substrate from the sulfuric acid bath, the substrate must be annealed so as to drive the protons to a depth sufficient to provide effective guiding.

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South Whitehall, PA, United States of America

Jeffrey B Bindell