Optical waveguide having two or more refractive indices and method of manufacturing same
AssigneeAlliedSignal Inc.
InventorsKarl W. Beeson, Scott M. Zimmerman, Paul M. Ferm
Life of this patent
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Abstract
An optical tapered waveguide for use as a single device or in optical arrays is described. The optical waveguide contains at least one inclusive structure. The inclusion may possess an abrupt refractive index interface within the body of the tapered optical waveguide or it may consist of a graded refractive index region within the tapered optical waveguide. Light travels through the entire waveguide structure via total internal reflection. The inclusion provides for a more uniform light distribution output and increases the definition of the image plane by altering the direction of the light rays passing through the waveguide.
Claims44
An optical waveguide for transmitting light comprising a material having an index of refraction n.sub.l and surrounded by a medium having an index of refraction n.sub.0 where n.sub.0 <n.sub.1, and said optical waveguide further comprising:
- a) an input surface for accepting a light distribution;
- b) an output surface distal from said input surface and having a surface area less than the surface area of said input surface;
- and
- c) an inclusion comprising a material having an index of refraction n.sub.2 and substantially surrounded by said material of index n.sub.1 and where n.sub.1 does not equal n.sub.2, and further comprising a surface area in a common plane as said input surface;
- whereby said inclusion acts to redirect light transmitting through said optical waveguide.
An optical waveguide for transmitting light comprising a material having an index of refraction n.sub.1, and further comprising:
- a) an input surface for accepting a light distribution;
- b) an output surface distal from said input surface;
- and
- c) inclusion for redirecting light transmitting through said optical waveguide comprising a material having a non-uniform index of refraction and substantially surrounded by said material of index n.sub.1 ;
- wherein said optical waveguide is surrounded by a medium having an index of refraction n.sub.0 where n.sub.0 <n.sub.1 and the area of said input surface is greater than the area of said output surface so that the angular distribution of light emerging from said output surface is larger than the angular distribution of light entering said input surface.
A process for manufacturing an optical waveguide having at least one inclusion comprising the steps of:
- (a) placing a photomask in substantial contact with a substrate wherein said photomask comprising opaque regions defining a transparent region and said transparent region comprises at least one opaque region;
- (b) placing a substantially uniform thickness of photopolymerizable mixture on said substrate so that said substrate is positioned between said photopolymerizable mixture and said photomask wherein;
- (i) said photopolymerizable mixture comprises at least one reactive monomer and photoinitiator, and
- (ii) said photoinitiator is present in an amount sufficient to form a gradient of substantially collimated actinic radiation across the thickness of said photopolymerizable mixture during subsequent step (c);
- (c) while maintaining said photopolymerizable mixture and substrate in a substantially fixed plane relative to said substantially collimated actinic radiation, exposing through said transparent regions of said photomask said photopolymerizable mixture to said substantially collimated actinic radiation for a time sufficient to form a tapered photopolymerized waveguide comprising at least one inclusion wherein:
- (i) the tapered end of said waveguide extends outward from said substrate, and
- (ii) said waveguide has a light input surface adjacent said substrate and a light output surface distal from said light input surface, wherein the area of the light input surface of each of said waveguides is greater than the area of its light output surface
- (d) removing said photomask and photopolymerizable mixture which was not substantially polymerized by said substantially collimated actinic radiation during step (c) from said substrate.
A process for manufacturing a tapered waveguide comprising the steps of;
- (a) placing a substantially uniform thickness of photopolymerizable mixture on a photomask wherein:
- (i) said photomask comprising opaque regions defining a transparent region and said transparent region comprises at least one opaque region,
- (ii) said photopolymerizable mixture comprises at least one reactive monomer and photoinitiator, and
- (iii) said photoinitiator is present in an amount sufficient to form a gradient of substantially collimated actinic radiation across the thickness of said photopolymerizable mixture during subsequent step (b);
- (b) while maintaining said photopolymerizable mixture and photomask in a substantially fixed plane relative to said substantially collimated actinic radiation, exposing through said transparent regions of said photomask said photopolymerizable mixture to said substantially collimated actinic radiation for a time sufficient to form a tapered photopolymerized waveguides comprising at least one inclusion wherein:
- (i) the tapered end of said waveguide extends outward from said photomask,
- (ii) said waveguides has a light input surface adjacent said photomask and a light output surface distal from said light input surface, and
- (iii) the area of the light input surface of said waveguides is greater than the area of its light output surface;
- and
- (c) removing photopolymerizable mixture which was not substantially polymerized by said substantially collimated actinic radiation during step (b) from said photomask.
Dependencies are inferred from the claim text.