Gray scale microfabrication for integrated optical devices
AssigneeLockheed Missiles and Space Comapny, Inc.
InventorsGeorge Gal, William W. Anderson, Bruce J. Herman, Marc A. Stiller
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Abstract
A monolithically integrated, micro-fabricated optical device for use in photonic applications has at least one waveguide surface configuration which cannot be fabricated by binary processing. The optical device comprises a plurality of layers of substrate materials. The material in at least one layer has an index of refraction different from the index of retraction of the material in an adjacent layer. A waveguide surface is formed at an interface between the layers and has a configuration fabricated by use of a gray scale mask.
Claims13
A method of fabricating within a volume of a photoresist material a replica of a photonic waveguide surface of any designed curved or inclined planar configuration, using a single exposure mask, and then producing a copy of the replica directly in a substrate material as the waveguide surface for ultimate use in photonic applications, said method comprising,
- constructing a single exposure mask with a plurality of precisely located and sized light transmitting openings formed with sufficiently small specific opening sizes and located at a sufficiently large number of specific locations, correlated to related locations on the configuration of the designed curved or inclined planar photonic waveguide surface, to enable a replica image of the said designed surface to be produced within a volume of a photoresist material,
- exposing a related photoresist material to light of a selected wavelength and transmitted through said openings in said single mask for a selected duration of time,
- processing the exposed photoresist material to produce a replica within the photoresist material of said designed surface, which replica can be used subsequently for producing a copy of the photoresist replica of said desired surface directly within the substrate material as the waveguide surface,
- placing the photoresist material replica on a first substrate material having a first index of refraction.
- processing the replica and the first substrate material to produce a copy of the photoresist replica of said desired surface directly within the substrate material as the waveguide surface and to remove a volume of the first substrate material which is bounded by the waveguide surface produced in the first substrate, and
- filling the removed volume with a second substrate material having a second index of refraction different from the first index of refraction of the first substrate material so that said waveguide surface is contained within the first substrate material at an interface between the first substrate material and the second substrate material.
A method of fabricating within a volume of a photoresist material a replica of a photonic waveguide surface of any designed configuration, using a single exposure mask, and reproducing the replica directly in a substrate material for ultimate use in photonic applications, said method comprising,
- constructing a single exposure mask with a plurality of precisely located and sized light transmitting openings formed with sufficiently small specific opening sizes and located at a sufficiently large number of specific locations, correlated to related locations on the configuration of the designed photonic waveguide surface, to enable a replica image of the said surface to be produced within a volume of a photoresist material
- exposing a related photoresist material to light of a selected wavelength and transmitted through said openings in said single mask for a selected duration of time
- processing the exposed photoresist material to produce a replica within the photoresist material of the said surface, which replica can be used subsequently for producing said surface in a substrate material,
- placing the photoresist material replica on a first substrate material having a first index of refraction,
- processing the replica and the first substrate material to reproduce the replica directly within the substrate material and to remove a volume of the first substrate material which is bounded by the replicated surface produced in the first substrate,
- filling the removed volume with a second substrate material having a second index of refraction different from the first index of refraction of the first substrate material, and
- wherein the first substrate is disposed in a first layer, the second substrate is disposed in a second layer, and
- wherein the second layer includes a portion which, as initially deposited, extends above the upper surface of the first layer by an amount sufficient to enable the reverse image of said configuration of the designed photonic waveguide surface to be formed in the thickness of the second layer which extends above the first layer, and including
- placing a layer of photoresist material on top of the layer of the second substrate,
- placing a second exposure mask constructed to produce said reverse image above the second layer of photoresist,
- exposing the second layer of photoresist,
- processing the exposed photoresist material to produce a replica of said reversed image in the photoresist material,
- processing the replica of said first reverse image and the second layer of substrate material to produce the replica directly within the second layer of substrate material and to remove a volume of the second layer from the substrate material which is bounded by the reversed image produced in the second layer of substrate, and
- cladding the processed reverse image in the second substrate with a third layer of substrate material having the same composition and index of refraction as said first layer of substrate material.
Dependencies are inferred from the claim text.