Holographic Waveguide Backlight and Related Methods of Manufacturing

Abstract

Systems and methods for holographic waveguide backlights in accordance with various embodiments of the invention are illustrated. One embodiment includes an optical illumination device including at least one waveguide, a source of light optically coupled to the at least one waveguide configured to emit light having a first polarization state, a first plurality of grating elements for diffracting the light having the first polarization state out of the at least one waveguide into a first set of output paths, a second plurality of grating elements for diffracting the light having the first polarization state light out of the at least one waveguide into a second set of output paths, and at least one input coupler configured to couple at least a portion of the light having the first polarization state towards the first and second pluralities of grating elements.

What is claimed is: 
     
         1 . An optical illumination device comprising:
 a light guiding structure with an upper surface for extracting illumination and a lower surface;   a light source optically coupled to said light guiding structure and configured to provide polarized light, said light undergoing total internal reflection within said light guiding structure; and   at least one plurality of grating elements disposed in at least one grating layer for extracting light from said light guiding structure.   
     
     
         2 . The optical illumination device of  claim 1 , wherein said light source is configured to emit at least first and second wavelength collimated light color sequentially, wherein said at least one plurality of grating elements comprises a first plurality of grating elements for diffracting said first wavelength light out of said light guiding structure into a first set of output paths, and a second plurality grating elements for diffracting said second wavelength light out of said light guiding structure into a second set of output paths substantially overlapping said first set of output paths. 
     
     
         3 . The optical illumination device of  claim 2 , further comprising a substrate having half-wave retarding regions interspersed with clear regions overlaying said upper surface, wherein each said half wave retarding region overlaps at least one grating element in each of said first and second pluralities of grating elements; and wherein each said clear region overlaps at least one grating element in each of said first and second pluralities of grating elements. 
     
     
         4 . The optical illumination device of  claim 2 , further comprising a quarter-wave retarding layer disposed, said quarter-wave retarding layer having a first surface disposed in proximity to said lower surface and a reflective surface. 
     
     
         5 . The optical illumination device of  claim 2 , wherein said first plurality of grating elements is disposed in a separate grating layer to said second plurality of grating elements, wherein grating elements for diffracting said first wavelength light overlap grating elements for diffracting said second wavelength light. 
     
     
         6 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first and second wavelength light are disposed as uniformly interspersed first and second multiplicities of grating elements in one layer. 
     
     
         7 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first and second wavelength light are disposed as uniformly interspersed first and second multiplicities of grating elements in two layers, wherein grating element for diffracting a first wavelength light overlap grating elements for diffracting second wavelength light. 
     
     
         8 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first wavelength light have a first grating vector and grating elements for diffracting second wavelength light have a second grating vector in an opposing direction to said first grating vector. 
     
     
         9 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first wavelength light and grating elements for diffracting second wavelength light have grating vectors aligned in substantially parallel directions. 
     
     
         10 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first wavelength light and grating elements for diffracting second wavelength light are off-Bragg with respect to each other. 
     
     
         11 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first wavelength light are disposed in a first layer in which grating elements having a first grating vector and grating elements having a second grating vector in an opposing direction to said first grating vector are uniformly interspersed, wherein grating elements for diffracting second wavelength light are disposed in a second layer in which grating elements having a first grating vector and grating elements having a second grating vector in an opposing direction to said first grating vector are interspersed. 
     
     
         12 . The optical illumination device of  claim 2 , wherein said first wavelength light has a first polarization and said second wavelength light has a second polarization orthogonal to said first polarization. 
     
     
         13 . The optical illumination device of  claim 2 , wherein said first wavelength light and said second wavelength light have the same polarization. 
     
     
         14 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first and second wavelength light are disposed as first and second multiplicities of grating elements multiplexed in a single layer, wherein grating elements for diffracting said first wavelength are multiplexed with grating elements for diffracting said second wavelength light. 
     
     
         15 . The optical illumination device of  claim 2 , wherein grating elements for diffracting first and second wavelength light are disposed as first and second multiplicities of grating elements in a stack of two contacting layers with grating elements for diffracting said first wavelength light overlapping grating elements for diffracting said second wavelength light. 
     
     
         16 . The optical illumination device of  claim 2 , wherein grating elements of said first plurality are switched into a diffracting state when said light source emits said first wavelength light and grating elements of said second plurality are switched into a diffracting state when said light source emits said second wavelength light. 
     
     
         17 . The optical illumination device of  claim 2 , wherein said output paths are angularly separated. 
     
     
         18 . The optical illumination device of  claim 2 , wherein said output paths are substantially normal to said upper surface. 
     
     
         19 . The optical illumination device of  claim 1 , wherein said at least one plurality of grating elements is disposed in at least one grating layer, wherein said light guiding structure comprises at least one waveguide, wherein each said waveguide supports at least one of said grating layers. 
     
     
         20 . The optical illumination device of  claim 1 , wherein said layer is formed between transparent substrates with transparent conductive coatings applied to each said substrate, at least one of said coatings being patterned into independently addressable elements overlapping said grating elements, wherein an electrical control circuit operative to apply voltages across each said grating elements is provided. 
     
     
         21 . The optical illumination device of  claim 1 , wherein each said grating element comprises at least one property selected from the group consisting of: a planar Bragg surfaces, optical power, optical retardation, diffusing properties, spatially varying diffraction efficiency, diffraction efficiency proportional to a voltage applied across said grating element, and phase retardation proportional to a voltages applied across said grating element. 
     
     
         22 . The optical illumination device of  claim 1 , wherein said at least one plurality of grating elements comprises a two-dimensional array. 
     
     
         23 . The optical illumination device of  claim 1 , wherein said at least one plurality of grating elements comprises a one-dimensional array of elongate elements. 
     
     
         24 . The optical illumination device of  claim 1 , wherein each said grating element is recorded in a Holographic Polymer Dispersed Liquid Crystal. 
     
     
         25 . The optical illumination device of  claim 1 , wherein said light is coupled into said light guide structure by a grating or a prism. 
     
     
         26 . The optical illumination device of  claim 1 , wherein said light source is laser or LED. 
     
     
         27 . The optical illumination device of  claim 1 , further comprising at least one component selected from the group consisting of: a beam deflector, a dichroic filter, a microlens array, beam shaper, light integrator, and a polarization rotator.