Method of making fluorine out-diffused optical device
AssigneeCorning Glass Works
InventorsRoger J. Araujo, Nicholas F. Borrelli, John D. Crow, Thomas P. Seward, III
Life of this patent
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Abstract
A fluorine containing silicate glass substrate is heated to a temperature sufficiently high to permit fluorine to out-diffuse from the surface thereof. A surface region is formed having a gradient fluorine concentration in a direction perpendicular to the substrate surface, the region of lowest fluorine concentration having the highest refractive index. The resultant device is capable of functioning as an optical waveguide.
Claims6
A method of forming a planar optical waveguide comprising the steps of
- providing a flat substrate of transparent silicate glass containing an amount of fluorine effective to decrease the refractive index thereof to a value below that of the silicate glass alone,
- polishing a surface of said substrate to form an optical quality surface, and
- heating said substrate to a temperature below the softening point temperature but greater than the annealing point temperature of said silicate glass, said temperature being sufficiently high to effect an out-diffusion of fluorine from said surface to form at said surface a layer of reduced fluorine content, the concentration of fluorine in said layer gradually increasing from a minimum value at said surface to a maximum value within said substrate so that the refractive index of said layer decreases from a maximum value at said surface to a minimum value within said substrate.
A method of forming a glass optical waveguide fiber having a refractive index distribution throughout its length such that in a plane perpendicular to the fiber optical axis the refractive index progressively decreases from a higher value at the optical axis of the fiber to a lower value at some finite fiber radius, said method comprising
- providing a hollow tube of transparent silicate glass containing an amount of fluorine effective to decrease the refractive index thereof to a value below that of the silicate glass alone,
- heating said tube to a temperature below the softening point temperature but greater than the annealing point temperature of said silicate glass, said temperature being sufficiently high to effect an out-diffusion of fluorine from at least the inner surface thereof to create at said inner surface a layer of reduced fluorine content, the concentration of fluorine in said layer gradually increasing from a minimum value at said inner surface to a maximum value within said tube, said fluorine out-diffusion process causing the refractive index of said tube to gradually decrease from a high value at the inner surface of said tube to a lower value within said tube,
- subjecting said tube to a temperature sufficiently high to permit said tube to be drawn into a fiber, and
- drawing said tube to collapse the hole in the center thereof and to reduce the cross-sectional area thereof and thereby form a glass optical fiber having a refractive index distribution throughout its length which progressively decreases from a high value at the optical axis of said fiber to a minimum value at some radius within said fiber.
Dependencies are inferred from the claim text.