Refractive Index Gradient Structuration by Thermal Poling in Amorphous Inorganic Materials

Abstract

Researchers at the University of Central Florida, the Institute of Condensed Matter Chemistry of Bordeaux, and the University of Bordeaux have invented a technology that surpasses the capabilities of conventional thermal poling techniques by giving optical manufacturers the flexibility and scale needed to fabricate arrays of micro-lenses. For example, in amorphous inorganic material (such as glass), the technology enables three dimensions of spatial control to create a refractive index gradient and up to a length scale of several hundreds of micrometers.

In standard thermal poling techniques, the electric field configuration strongly limits the cations to move in directions parallel to the surface of the treated material. Thus, the refractive index gradient cannot be fully controlled. This limitation also causes abrupt transitions from regions of low index refraction to high index refraction, prohibiting a smoother periodic variation of the refractive index on a larger length scale.

Technical Details

The invention is a device and method for inducing by thermal poling a spatially controlled refractive index gradient inside at least one amorphous inorganic material to be treated. It includes a structured electrode arranged on the surface or in proximity to the surface of the material to be treated and at least one dielectric material. The structured electrode includes at least one conductive zone and at least one non-conductive zone. It is confined between the amorphous inorganic material to be treated and the dielectric material.

In one example application, the amorphous inorganic material to be treated is a chalcogenide glass or an oxide glass of the soda-lime silicate family. The dielectric material is an oxide glass of the soda-lime silicate family. The structured electrode is a thin layer of Indium tin oxide (ITO) deposited on an electrically insulating substrate. It is partially ablated to induce a structure of alternating electrically conductive and electrically insulating zones or a nickel grid. N2 forms the controlled atmosphere. Chalcogenide glasses and oxide glasses of the soda-lime silicate family include a wide range of materials whose optical properties cover a large portion of the electromagnetic spectrum. Also, chalcogenide glasses are transparent in infrared light, allowing applications for which other materials are not suited.

Benefit

Market Application