OPTICAL WAVEGUIDES HAVING DIFFRACTION GRATINGS FOR BEAM REDIRECTION
First Claim
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1. An optical waveguide for a near-eye display, the optical waveguide comprising:
- a slab of transparent material;
a first grating structure supported by the slab and having a first spatial variation of optical permittivity, wherein the first spatial variation has a first grating pitch and a wavelength-dependent first amplitude, such that at a first wavelength, the first amplitude is above a first threshold and at a second wavelength, the first amplitude is below a second threshold, wherein the second threshold is lower than the first threshold; and
a second grating structure supported by the first grating structure and having a second spatial variation of optical permittivity, wherein the second spatial variation has a second grating pitch and a wavelength-dependent second amplitude, such that at the first wavelength, the second amplitude is below the second threshold and at the second wavelength, the second amplitude is above the first threshold.
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Abstract
A diffraction grating with independently controlled diffraction angles for optical beams at different wavelengths may be used to redirect and couple light to a waveguide in an efficient, space-saving manner. The diffraction grating can include a layer with optical permittivity and associated index contrast of the grating grooves at different grating periods dependent on wavelength.
4 Citations
20 Claims
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1. An optical waveguide for a near-eye display, the optical waveguide comprising:
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a slab of transparent material; a first grating structure supported by the slab and having a first spatial variation of optical permittivity, wherein the first spatial variation has a first grating pitch and a wavelength-dependent first amplitude, such that at a first wavelength, the first amplitude is above a first threshold and at a second wavelength, the first amplitude is below a second threshold, wherein the second threshold is lower than the first threshold; and a second grating structure supported by the first grating structure and having a second spatial variation of optical permittivity, wherein the second spatial variation has a second grating pitch and a wavelength-dependent second amplitude, such that at the first wavelength, the second amplitude is below the second threshold and at the second wavelength, the second amplitude is above the first threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An optical waveguide for a near-eye display, the optical waveguide comprising:
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a slab of transparent material; and a diffraction grating supported by the slab and comprising a layer of material having a spatially varying optical permittivity dependent on wavelength, such that; at a first wavelength, the spatially varying optical permittivity comprises a plurality of peaks and valleys at a first pitch; and at a second, different wavelength, the spatially varying optical permittivity comprises a plurality of peaks and valleys at a second, different pitch. - View Dependent Claims (14, 15, 16, 17)
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18. A near-eye display comprising:
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an electronic display for providing image light comprising first and second color channels; an optical waveguide configured to receive and guide therein the image light from the electronic display, the optical waveguide comprising; a slab of transparent material; a first diffraction grating supported by the slab and configured for receiving the image light from the electronic display for in-coupling to the slab; and a second diffraction grating supported by the slab and configured for receiving the image light from the first diffraction grating through the slab for out-coupling the light from the slab; wherein at least one of the first and second diffraction gratings comprises a layer of material having a spatially varying optical permittivity dependent on wavelength, such that; at a first wavelength of the first color channel, the spatially varying optical permittivity comprises a plurality of peaks and valleys at a first pitch; and at a second wavelength of the second color channel, the spatially varying optical permittivity comprises a plurality of peaks and valleys at a second, different pitch. - View Dependent Claims (19, 20)
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Specification