Manufacturing a graded index profile for waveguide display applications

Abstract

A manufacturing system for fabricating optical waveguides includes a diffusion channel with a plurality of inlets at a first end and an outlet at a second end opposite to the first end and separated from the inlets by a channel length. Each of the plurality of inlets includes a central inlet flowing a first resin into the diffusion channel such that the first resin flows along the channel length of the diffusion channel toward the outlet, and an outer inlet flowing a second resin along a periphery of the first resin. The second resin may have an index of refraction different than the first resin. The diffusion may occur between portions of the first resin and portions of the second resin over the channel length to form a composite resin having a profile with a plurality of indices of refraction in at least one dimension.

What is claimed is: 
     
         1 . A system comprising:
 a diffusion channel comprising a plurality of inlets at a first end and an outlet at a second end opposite to the first end and separated from the plurality inlets by a channel length, the plurality of inlets comprising:   a central inlet configured to input a first resin into the diffusion channel such that the first resin flows along the channel length of the diffusion channel toward the outlet, and   an outer inlet configured to input a second resin along a periphery of the first resin, the second resin having a refractive index different from a refractive index of the first resin;   wherein diffusion occurs between portions of the first resin and portions of the second resin over the channel length to form a composite resin having a substantially graded refractive index profile with a refractive index spatially varying along a thickness dimension of the composite resin.   
     
     
         2 . The system of  claim 1 , further comprising:
 a diffusion system for applying the composite resin onto a substrate; and   a rotating assembly configured to move the substrate along a length dimension orthogonal to the thickness dimension.   
     
     
         3 . The system of  claim 1 , further comprising an irradiation system configured to cure at least a portion of the composite resin. 
     
     
         4 . The system of  claim 1 , wherein the substantially graded refractive index profile substantially does not vary along width and length dimensions of the composite resin, wherein the width, length, and thickness dimensions are orthogonal to one another. 
     
     
         5 . The system of  claim 1 , wherein the spatially varying value of the refractive index comprises a parabolic index profile. 
     
     
         6 . The system of  claim 1 , wherein the first resin and the second resin comprise at least one of polyacrylate, polyurethane, polysilicone, polyester, polyolefin, polyamide, or polycarbonate. 
     
     
         7 . The system of  claim 1 , wherein the substantially graded refractive index profile is achieved by selecting at least one of: a flow rate of the first resin and the second resin; a time allowed for the occurrence of diffusion; a proportion of the first resin with respect to the second resin; or a gradient of temperature across the diffusion channel. 
     
     
         8 . The system of  claim 1 , wherein the substantially graded refractive index profile is rotationally symmetric. 
     
     
         9 . The system of  claim 1 , further comprising a second outer inlet configured to input the second resin along the periphery of the first resin. 
     
     
         10 . The system of  claim 1 , wherein the diffusion channel is substantially flat, and wherein the center inlet and the outer inlet are disposed to provide the composite resin with the refractive index varying along a thickness dimension of the diffusion channel and not varying along a length and width dimension of the diffusion channel. 
     
     
         11 . A system comprising:
 a substantially flat diffusion channel having mutually perpendicular thickness, length, and width dimensions;   a central inlet configured to input a first resin into the diffusion channel for flowing the first resin in the diffusion channel along the length dimension towards an outlet of the diffusion channel;   a first outer inlet configured to input a second resin into the diffusion channel for co-flowing the second resin with the first resin in the diffusion channel along its length dimension towards the outlet;   wherein diffusion occurs between portions of the first and second resins as the first and second resins co-flow in the diffusion channel, to form a composite resin having a substantially graded refractive index profile with a refractive index varying along the thickness dimension of the diffusion channel.   
     
     
         12 . The system of  claim 11 , further comprising a second outer inlet disposed on an opposite side of the central inlet from the first outer inlet, wherein the second outer inlet is configured to input a third resin into the diffusion channel for co-flowing the third resin with the first and second resins in the diffusion channel along the length dimension towards the outlet. 
     
     
         13 . The system of  claim 12 , wherein the second and third resins comprise a same resin. 
     
     
         14 . The system of  claim 11 , wherein the first resin and the second resin comprise at least one of polyacrylate, polyurethane, polysilicone, polyester, polyolefin, polyamide, or polycarbonate. 
     
     
         15 . The system of  claim 11 , wherein the substantially graded refractive index profile is achieved by selecting at least one of: a flow rate of the first resin and the second resin, a time allowed for the occurrence of diffusion, a proportion of the first resin with respect to the second resin, or a gradient of temperature across the diffusion channel. 
     
     
         16 . The system of  claim 11 , wherein the substantially graded refractive index profile is symmetric. 
     
     
         17 . The system of  claim 11 , further comprising a curing unit for curing the composite resin by at least one of: heating the composite resin; or irradiating the composite resin with an actinic radiation. 
     
     
         18 . A waveguide comprising:
 a solid composite resin waveguide body comprising:
 a first surface; 
 a second surface parallel to the first surface; and 
 a central layer in between the first surface and the second surface; 
 wherein the solid composite resin has a substantially graded refractive index profile with a refractive index varying along a first dimension orthogonal to the first and second surfaces, wherein the refractive index is substantially not varying along second and third dimensions parallel to the first and second surfaces, wherein the first, second, and third dimensions are orthogonal to each other; and 
 wherein the solid composite resin includes a cured inter-diffused mixture of first and second resins, wherein a refractive index of the first resin is different from a refractive index of the second resin. 
   
     
     
         19 . The waveguide of  claim 18 , wherein the solid complex resin is manufactured by a process comprising:
 flowing the first resin into a central flat inlet of a plurality of inlets at a first end of the diffusion channel-including an outlet at a second end opposite to the first end and separated from the plurality of inlets by a channel length; and   flowing the second resin into an outer flat inlet of the plurality of inlets along a periphery of the first resin;   wherein at least a portion of the second resin diffuses into at least a portion of the first resin in the diffusion channel over the channel length to form a mixture of the first resin and the second resin.   
     
     
         20 . The waveguide of  claim 19 , wherein the process further comprises controlling at least one of: a first flow rate of the first resin, a second flow rate of the second resin, a time allowed for the diffusion, a proportion of the first resin to the second resin, or a gradient of temperature across the diffusion channel.