| 摘要 |
Optical waveguide paths are formed under the surface of a glass substrate by a method comprising (a) forming by ion-exchange a dopant ion path on a first substrate surface, (b) applying an electrode to the second surface, (c) contacting the first surface with a molten salt bath, and (d) applying an electrical field across the substrate to drive the dopant ions deeper into the substrate. The current resulting from high fields can overheat the substrate, thereby causing substrate warping and burying of paths to uneven depths. One aspect of the invention involves cooling the substrate by flowing the molten salt along the first surface of the substrate at a sufficient rate of flow to adequately decrease its temperature and by rapidly flowing the furnace atmosphere over the surface of the substrate. A further aspect of the invention involves initially applying a voltage Vi across the substrate, allowing the current to increase to a predetermined level Im, and maintaining the flow of current at the predetermined level Im by decreasing the applied voltage at a rate necessarry to maintain the current at level Im. The electrical field remains for a predetermined period of time to bury the ion path a predetermined depth.
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