Method for the production of light conductor structures with interlaying electrodes

Claim 1

A method of forming a light conductor structure having a pair of light conductors embedded in one surface of a substrate of an electro-optical material having its c-axis extending parallel to the one surface and at right angles to the light conductors and having electrodes extending between the light conductors, said structure being particularly adapted for use as an electrically controllable coupler, said method comprising the steps of providing a substrate of the electro-optical material having said one surface; applying a layer of polycrystalline silicon on said one surface of the substrate; removing a portion of the silicon layer from said one surface by etching to provide silicon-free portions of said one surface having a configuration of the light conductors, which are to be formed, with the remaining portions of the silicon layer forming a mask; applying a layer of diffusion material on the silicon layer and said silicon-free portions of said one surface of the substrate; diffusing the diffusion material into the surface of the substrate at said silicon-free portions to form light conductors having an index of refraction greater than the index of refraction of the substrate by heating to an elevated temperature; cooling the substrate; applying a layer of negative acting photo-lacquer to the light conductors and the layer of diffusion material; exposing said layer of negative acting photo-lacquer by projecting light through the substrate with the remaining portions of the silicon layer acting as a mask; developing the layer of photo-lacquer so that the unexposed portions are removed and the remaining portions of the lacquer cover the light conductors; removing the remaining portions of the silicon layer with the diffusion layer thereon from said one surface; applying a metal layer on said one surface to form the electrodes and then removing the photo-lacquer strips with the metal deposited thereon from the light conductors.

Claim 2

A method of forming a light conductor structure having a pair of light conductors embedded in one surface of a substrate of an electro-optical material having its c-axis extending parallel to the one surface and at right angles to the light conductors and having electrodes extending between the light conductors, said structure being particularly adapted for use as an electrically controllable coupler, said method comprising the steps of providing a substrate of the electro-optical material having said one surface; applying a layer of polycrystalline silicon on said one surface of the substrate; removing a portion of the silicon layer from said one surface by etching to provide silicon-free portions of said one surface having a configuration of the light conductors, which are to be formed, with the remaining portions of the silicon layer forming a mask; applying a layer of diffusion material on the silicon layer and said silicon-free portions of said one surface of the substrate; diffusing the diffusion material into the surface of the substrate at said silicon-free portions to form light conductors having an index of refraction greater than the index of refraction of the substrate by heating to an elevated temperature; cooling the substrate; applying a layer of negative acting photo-lacquer to the light conductors and the layer of diffusion material; exposing said layer of negative acting photo-lacquer by projecting light through the substrate with the remaining portions of the silicon layer acting as a mask; developing the layer of photo-lacquer so that the unexposed portions are removed and the remaining portions of the lacquer cover the light conductors; removing the remaining portions of the silicon layer with the diffusion layer thereon from said one surface; applying a metal layer on said one surface to form the electrodes and then removing the photo-lacquer strips with the metal deposited thereon from the light conductors.