Polaroid Corporation

William C Robinson

Norman A Sanford

Donald H McMahon

Amaresh Mahapatra

An external light modulator which relies on efficient changes in electro-optic coupling of light between copolarized guided modes in a single waveguide channel formed in a lithium niobate or lithium tantalate substrate by proton exchange with benzoic acid.

Optical modulation device

A planar waveguide device including metallic electrodes has a buffer layer of reduced ordinary index of refraction formed in a substrate between its waveguide and electrodes. The device is preferably formed by first fabricating the waveguide in an x-or y-cut substrate of crystalline material, subsequently overcoating the substrate, including the waveguide, with a layer of magnesium, oxidizing the magnesium at temperature to form the buffer layer and then laying the electrodes over the buffer layer. Alternatively, the buffer layer may be formed by a proton exchange process.

Planar waveguide mode converter device

Integrated optic resonant structures for use in optical communications and sensing applications requiring control or detection of electromagnetic radiation in the optical region of the spectrum. Preferably of planar form, the structures comprise a substrate made of a ferroelectric crystalline material in which there is formed by selectively exchanging protons for an ionic constituent of the substrate at least one optically continuous waveguiding region having predetermined resonant characteristics. At least one other waveguiding region is similarly formed in the substrate to optically couple with the resonant region and includes at least one port by which radiation can be coupled in and out of the substrate. The substrate material is preferably lithium niobate (LiNbO.sub.3) or lithium tantalate (LiTaO.sub.3) in which lithium ions are selectively exchanged for protons supplied by diffusion from a hydrogen rich acid. Applications for the structures include use as a band pass or reject filter, bus tap, sensor, or modulator.

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Concord, MA, United States of America

William C Robinson