Light guide apparatus and fabrication method thereof

Abstract

A light guide apparatus that can redirect light impinging on the apparatus over a wide range of incident angles and can concentrate light without using a tracking system and methods for fabrication. This apparatus uses conditions of total internal reflection and refraction near the critical angle for total internal reflection (near TIR) in order to trap light within the apparatus.

1 . An optical apparatus having two or more layers; the two or more layers configured in a stacked configuration; the optical apparatus having two opposite surfaces labeled an exterior surface and a bounding surface; the two or more layers being disposed between the two opposite surfaces;
 a layer closest to the exterior surface comprising:   a first optically transparent medium;   a second optically transparent medium;   an interface between the first optically transparent medium and the second optically transparent medium; said interface configured such that light incident on the first optically transparent medium in a predetermined range of angles is bent at said interface by at least one of refraction, total internal reflection (TIR) and near TIR;   a third optically transparent medium; and   an interface between the second and third optically transparent media; the interface between the second and third optically transparent media configured such that light incident on the first optically transparent medium in the predetermined range of angles and propagating in the second optically transparent medium propagates substantially parallel to one face of a microstructured cross-section of the interface between the second and third optically transparent media and substantially perpendicular to another face of the microstructured cross-section of the interface between the second and third optically transparent media;   
       each one layer of the other of the two or more layers comprising:
 a first optically transparent medium of said one layer; said first optically transparent medium of said one layer being closest to the exterior surface; 
 a second optically transparent medium of said one layer; and 
 
       an interface between said first and second optically transparent media of said one layer; 
       the interface between said first and second optically transparent media of said one layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles and propagating in the first optically transparent medium of said one layer propagates substantially parallel to one face of a microstructured cross-section of the interface between the first and second optically transparent media of said one layer and substantially perpendicular to another face of the microstructured cross-section of the interface between the first and second optically transparent media of said one layer; 
       said first optically transparent medium of said one layer being disposed between a first planar surface and said interface between said first and second optically transparent media of said one layer; 
       said second optically transparent medium of said one layer being disposed between said interface between said first and second optically transparent media of said one layer and a second planar surface; 
       indices of refraction of optically transparent media of each layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles bends and propagates towards the bounding surface. 
     
     
         2 . The optical apparatus of  claim 1 , wherein, in a layer from the two or more layers and closest to the bounding surface, the second planar surface is coincident with the bounding surface; wherein the indices of refraction of the optically transparent media of said layer are configured such that light incident on the bounding surface is totally internally reflected; and wherein the interface between the first and second optically transparent media of said layer from the two or more layers and closest to the bounding surface is also configured such that light totally internally reflected from the bounding surface is bent at said interface by at least one of refraction, total internal reflection (TIR) and near TIR so that the light is not incident on the first planar surface of said layer. 
     
     
         3 . The optical apparatus of  claim 2  wherein the optical apparatus has a first end and a second end, each one of the first and second ends extending from the exterior surface to the bounding surface; wherein the light incident on the exterior surface in a predetermined range of angles propagates in said layer closest to the bounding surface towards the second end; and wherein the optical apparatus also comprises a solar cell disposed on the second end. 
     
     
         4 . The optical apparatus of  claim 2  wherein the optical apparatus has a first end and a second end, each one of the first and second ends extending from the exterior surface to the bounding surface; wherein the light incident on the exterior surface in a predetermined range of angles propagates in said layer closest to the bounding surface towards the second end; wherein the second end is beveled and configured to redirect the light towards the bounding surface; and wherein the optical apparatus also comprises a solar cell disposed on the bounding surface at a location configured to receive the light redirected by the beveled second end. 
     
     
         5 . A hybrid solar panel comprising:
 the optical apparatus of  claim 2  wherein the optical apparatus has a first end and a second end, each one of the first and second ends extending from the exterior surface to the bounding surface; wherein the light incident on the exterior surface in a predetermined range of angles propagates in said layer closest to the bounding surface towards the second end; wherein the second end is beveled and configured to redirect the light towards the bounding surface;
 a layer of low refractive index material, the low refractive index material having a refractive index configured to ensure that light incident on the bounding surface from the second optically transparent media of said layer from the two or more layers and closest to the bounding surface is totally internally reflected; the optical apparatus of  claim 2  being disposed on one surface of the layer of low refractive index material; 
 a multi-junction solar cell disposed on an opposite surface of the low refractive index material at a location configured to receive the light redirected by the beveled second end; and 
 a single junction solar cell disposed on the opposite surface of the low refractive index material at a location configured to receive diffused light incident on the exterior surface, and transmitted through the optical apparatus of  claim 2 . 
   
     
     
         6 . An optical apparatus having two or more layers; the two or more layers configured in a stacked configuration; the optical apparatus having two opposite surfaces labeled an exterior surface and a focal plane surface; the two or more layers being disposed between the two opposite surfaces;
 a layer closest to the exterior surface comprising:   a first optically transparent medium;   a second optically transparent medium;   an interface between the first optically transparent medium and the second optically transparent medium; said interface configured such that light incident on the first optically transparent medium in a predetermined range of angles is bent at said interface by at least one of refraction, total internal reflection (TIR) and near TIR;   a third optically transparent medium; and   an interface between the second and third optically transparent media; the interface between the second and third optically transparent media configured such that light incident on the first optically transparent medium in the predetermined range of angles and propagating in the second optically transparent medium propagates substantially parallel to one face of a microstructured cross-section of the interface between the second and third optically transparent media and substantially perpendicular to another face of the microstructured cross-section of the interface between the second and third optically transparent media;   
       each one layer of the other of the two or more layers comprising:
 a first optically transparent medium of said one layer; said first optically transparent medium of said one layer being closest to the exterior surface; 
 a second optically transparent medium of said one layer; and 
 
       an interface between said first and second optically transparent media of said one layer; 
       the interface between said first and second optically transparent media of said one layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles and propagating in the first optically transparent medium of said one layer propagates substantially parallel to one face of a microstructured cross-section of the interface between the first and second optically transparent media of said one layer and substantially perpendicular to another face of the microstructured cross-section of the interface between the first and second optically transparent media of said one layer; 
       indices of refraction of optically transparent media of each layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles bends and propagates towards one or more focal points on the focal plane surface; 
       microstructure of each interface between optically transparent media being configured to vary with position along said each interface source that light incident on the layer closest to the exterior surface in the predetermined range of angles converges to the one or more focal points. 
     
     
         7 . The optical apparatus of  claim 6  wherein the one or more focal points are one focal point; and wherein said microstructure of said each interface is meters symmetrical about an optical axis from the one focal point to the exterior surface. 
     
     
         8 . The optical apparatus of  claim 6  wherein a microstructure of the interface between the first optical medium and a second optical medium in the layer closest to the exterior surface is at least one of a right angle prism array, a V-groove prism array and a scalene prism array. 
     
     
         9 . The optical apparatus of  claim 6  wherein the one or more focal points are two or more focal points; and wherein a light source from a plurality of light sources is disposed at each one of the two or more focal points and emits light into the optical apparatus. 
     
     
         10 . An angle selective reflector having one or more layers; the one or more layers configured in a stacked configuration; the angle selective reflector having two opposite surfaces labeled an exterior surface and a bounding surface; the one or more layers being disposed between the two opposite surfaces;
 each one layer of one or more layers comprising:
 a first optically transparent medium of said one layer; said first optically transparent medium of said one layer being closest to the exterior surface; 
 a second optically transparent medium of said one layer; and 
 an interface between said first and second optically transparent media of said one layer; the interface between said first and second optically transparent media of said one layer being configured such that light incident on a layer closest to the exterior surface in a predetermined range of angles and propagating in the first optically transparent medium of said one layer propagates substantially parallel to one face of a microstructured cross-section of the interface between the first and second optically transparent media of said one layer and substantially perpendicular to another face of the microstructured cross-section of the interface between the first and second optically transparent media of said one layer; 
 said first optically transparent medium of said one layer being disposed between a first planar surface and said interface between said first and second optically transparent media of said one layer; 
 said second optically transparent medium of said one layer being disposed between said interface between said first and second optically transparent media of said one layer and a second planar surface; 
 indices of refraction of optically transparent media of each layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles bends and propagates towards the bounding surface, and, in the layer closest to the bounding surface, is totally internally reflected at the second planar surface of a layer closest to the bounding surface. 
   
     
     
         11 . The angle selective reflector of  claim 10  wherein only one layer is included in the one or more layers. 
     
     
         12 . The angle selective reflector of  claim 10  wherein the one or more layers are two or more layers. 
     
     
         13 . The angle selective reflector of  claim 12  wherein, in said each one layer, the interface between said first and second optically temporary media of said each one layer comprises sections where said interface is a flat surface and sections where said interface is microstructured; each microstructured section being followed by a flat surface section; a pattern of flat surface sections and microstructured sections being a same pattern in each layer; wherein light incident on the exterior surface is another predetermined range of angles and at a location where each interface has a flat surface section is transmitted through the angle selective reflector. 
     
     
         14 . A window comprising:
 a layer of optically transparent material; and   the angle selective reflector of  claim 13  disposed on the layer of optically transparent material;   the bounding surface being disposed on a surface of the layer of optically transparent material.   
     
     
         15 . An optical device comprising:
 an optical component having two or more layers; the two or more layers configured in a stacked configuration; the optical component having two opposite surfaces labeled an exterior surface and a bounding surface; the two or more layers being disposed between the two opposite surfaces;   
       each one layer of two or more layers comprising:
 a first optically transparent medium of said one layer; said first optically transparent medium of said one layer being closest to the exterior surface; 
 a second optically transparent medium of said one layer; and 
 an interface between said first and second optically transparent media of said one layer; 
 said first optically transparent medium of said one layer being disposed between a first planar surface and said interface between said first and second optically transparent media of said one layer; 
 said second optically transparent medium of said one layer being disposed between said interface between said first and second optically transparent media of said one layer and a second planar surface; 
 
       in the stacked configuration, the second planar surface of one layer is disposed on the first planar surface of another layer; 
       a light source configured to emit light at a wide range of angles; the light source being disposed to emit light onto the exterior surface; and 
       a reflector; the light source being disposed between the reflector and the exterior surface; 
       indices of refraction of optically transparent media of each layer being configured such that an index of refraction of the first optically transparent medium is higher than an index of refraction of the second optically transparent medium; 
       an index of refraction of the second optically transparent medium of one layer, the one layer being closer to the exterior surface, being higher than an index of refraction of the first optically transparent medium of a layer in contact with the one layer and further away from the exterior surface; 
       the interface between the first and second optically transparent media of said one layer being microstructured and configured such that light from the light source incident on an “onward” face of a microstructure is transmitted through the interface and source that light from the light source incident on a “leeward” face of the microstructure undergoes total internal reflection of and subsequent refraction. 
     
     
         16 . The optical device of  claim 15  wherein the reflector is a specular reflector. 
     
     
         17 . The optical device of  claim 15  wherein the reflector is a nonspecular reflector. 
     
     
         18 . A method for trapping light comprising:
 providing light incident on an exterior surface of an optical apparatus and in a predetermined range of angles; the optical apparatus comprising:   two or more layers; the two or more layers configured in a stacked configuration; the optical apparatus having two opposite surfaces labeled the exterior surface and a bounding surface; the two or more layers being disposed between the two opposite surfaces;
 a layer closest to the exterior surface comprising: 
 a first optically transparent medium; 
 a second optically transparent medium; 
 an interface between the first optically transparent medium and the second optically transparent medium; said interface configured such that light incident on the first optically transparent medium in a predetermined range of angles is bent at said interface by at least one of refraction, total internal reflection (TIR) and near TIR; 
 a third optically transparent medium; and 
 an interface between the second and third optically transparent media; the interface between the second and third optically transparent media configured such that light incident on the first optically transparent medium in the predetermined range of angles and propagating in the second optically transparent medium propagates substantially parallel to one face of a microstructured cross-section of the interface between the second and third optically transparent media and substantially perpendicular to another face of the microstructured cross-section of the interface between the second and third optically transparent media; 
   each one layer of the other of the two or more layers comprising:
 a first optically transparent medium of said one layer; said first optically transparent medium of said one layer being closest to the exterior surface; 
 a second optically transparent medium of said one layer; and 
 an interface between said first and second optically transparent media of said one layer; the interface between said first and second optically transparent media of said one layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles and propagating in the first optically transparent medium of said one layer propagates substantially parallel to one face of a microstructured cross-section of the interface between the first and second optically transparent media of said one layer and substantially perpendicular to another face of the microstructured cross-section of the interface between the first and second optically transparent media of said one layer; 
 said first optically transparent medium of said one layer being disposed between a first planar surface and said interface between said first and second optically transparent media of said one layer; 
 said second optically transparent medium of said one layer being disposed between said interface between said first and second optically transparent media of said one layer and a second planar surface; 
   indices of refraction of optically transparent media of each layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles bends and propagates towards the bounding surface;   wherein, in a layer from the two or more layers and closest to the bounding surface, the second planar surface is coincident with the bounding surface; wherein the indices of refraction of the optically transparent media of said layer are configured such that light incident on the bounding surface is totally internally reflected; and wherein the interface between the first and second optically transparent media of said layer from the two or more layers and closest to the bounding surface is also configured such that light totally internally reflected from the bounding surface is bent at said interface by at least one of refraction, total internal reflection (TIR) and near TIR so that the light is not incident on the first planar surface of said layer.   
     
     
         19 . A method for photovoltaic energy conversion, the method comprising:
 providing light incident on an exterior surface of the optical apparatus described in  claim 15  and in a predetermined range of angles; wherein the optical apparatus has a first end and a second end, each one of the first and second ends extending from the exterior surface to the bounding surface; wherein the light incident on the exterior surface in a predetermined range of angles propagates in said layer closest to the bounding surface towards the second end; and wherein the optical apparatus also comprises a solar cell disposed on the second end; and   wherein the solar cell converts light into electricity.   
     
     
         20 . A method for photovoltaic energy conversion, the method comprising:
 providing light incident on an exterior surface of the optical apparatus described in  claim 15  and in a predetermined range of angles; wherein the optical apparatus has a first end and a second end, each one of the first and second ends extending from the exterior surface to the bounding surface; wherein the light incident on the exterior surface in a predetermined range of angles propagates in said layer closest to the bounding surface towards the second end; wherein the second end is beveled and configured to redirect the light towards the bounding surface; and wherein the optical apparatus also comprises a solar cell disposed on the bounding surface at a location configured to receive the light redirected by the beveled second end;   wherein the solar cell converts light into electricity.   
     
     
         21 . A method for modifying emission from an array of light sources, the method comprising:
 providing a flat lens comprising: two or more layers; the two or more layers configured in a stacked configuration; the flat lens having two opposite surfaces labeled an exterior surface and a focal plane surface; the two or more layers being disposed between the two opposite surfaces;
 a layer closest to the exterior surface comprising: 
 a first optically transparent medium; 
 a second optically transparent medium; 
 an interface between the first optically transparent medium and the second optically transparent medium; said interface configured such that light incident on the first optically transparent medium in a predetermined range of angles is bent at said interface by at least one of refraction, total internal reflection (TIR) and near TIR; 
 a third optically transparent medium; and 
 an interface between the second and third optically transparent media; the interface between the second and third optically transparent media configured such that light incident on the first optically transparent medium in the predetermined range of angles and propagating in the second optically transparent medium propagates substantially parallel to one face of a microstructured cross-section of the interface between the second and third optically transparent media and substantially perpendicular to another face of the microstructured cross-section of the interface between the second and third optically transparent media; 
 each one layer of the other of the two or more layers comprising: 
 a first optically transparent medium of said one layer; said first optically transparent medium of said one layer being closest to the exterior surface; 
 a second optically transparent medium of said one layer; and 
 an interface between said first and second optically transparent media of said one layer; the interface between said first and second optically transparent media of said one layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles and propagating in the first optically transparent medium of said one layer propagates substantially parallel to one face of a microstructured cross-section of the interface between the first and second optically transparent media of said one layer and substantially perpendicular to another face of the microstructured cross-section of the interface between the first and second optically transparent media of said one layer; 
   indices of refraction of optically transparent media of each layer being configured such that light incident on the layer closest to the exterior surface in the predetermined range of angles bends and propagates towards one or more focal points on the focal plane surface;   microstructure of each interface between the optically transparent media being configured to vary with position along said each interface source that light incident on the layer closest to the exterior surface in the predetermined range of angles converges to the one or more focal points; wherein the one or more focal points are two or more focal points;   placing a light source from a plurality of light sources at each one of the two or more focal points;   wherein, due to time reversal invariance of electromagnetic fields, light is emitted from the flat lens into the predetermined range of angles.