Diffractive devices based on cholesteric liquid crystal
First Claim
1. A diffraction grating comprising:
- a cholesteric liquid crystal (CLC) layer comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction,wherein the helical pitch is a length in the layer depth direction corresponding to a net rotation angle of the liquid crystal molecules of the chiral structures by one full rotation in the first rotation direction, andwherein arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction, andwherein the chiral structures comprise a plurality of first liquid crystal molecules stacked over a plurality of second liquid crystal molecules, wherein the first liquid crystal molecules and the second liquid crystal molecules extend in the layer depth direction at different helical pitches.
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Abstract
Examples of diffractive devices comprise a cholesteric liquid crystal (CLC) layer comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction. Arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction to provide a diffraction grating. The diffractive devices can be configured to reflect light having a particular wavelength range and sense of circular polarization. The diffractive devices can be used in waveguides and imaging systems in augmented or virtual reality systems.
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Citations
23 Claims
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1. A diffraction grating comprising:
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a cholesteric liquid crystal (CLC) layer comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction, wherein the helical pitch is a length in the layer depth direction corresponding to a net rotation angle of the liquid crystal molecules of the chiral structures by one full rotation in the first rotation direction, and wherein arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction, and wherein the chiral structures comprise a plurality of first liquid crystal molecules stacked over a plurality of second liquid crystal molecules, wherein the first liquid crystal molecules and the second liquid crystal molecules extend in the layer depth direction at different helical pitches. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A wave-guiding device, comprising:
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one or more cholesteric liquid crystal (CLC) layers each comprising a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction and are successively rotated in a first rotation direction, wherein arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction such that the one or more CLC layers are configured to Bragg-reflect incident light; and one or more waveguides formed over the one or more CLC layers and configured to optically couple Bragg-reflected light from the one or more CLC layers such that the Bragg-reflected light travels in a lateral direction perpendicular to the layer depth direction by total internal reflection (TIR), wherein the one or more CLC layers and the one or more waveguides are configured to be in the same optical path, and wherein the chiral structures comprise a plurality of first liquid crystal molecules stacked over a plurality of second liquid crystal molecules, wherein the first liquid crystal molecules and the second liquid crystal molecules extend in the layer depth direction at different helical pitches. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification