Waveguide for an augmented reality or virtual reality display and method of manufacture of the same

Abstract

This invention discloses a waveguide (1) for an augmented reality or virtual reality display, comprising: an output diffraction element including a plurality of optical structures (22, 28, 26) in a photonic crystal; a first primary surface and a second primary surface of the waveguide, the first primary surface being separated from the second primary surface in a direction perpendicular to a plane of the waveguide, wherein light propagates along the waveguide toward the output diffraction element by total internal reflection between the first and second primary surfaces, wherein the plurality of optical structures (22, 28, 26) are configured to receive light from an input direction and diffract the light into a plurality of levels of array. Arranged in a plane of the waveguide, some stages are diffracted at an angle to the input direction in the plane of the waveguide to provide 2D extension across the plane of the waveguide, and other stages are externally coupled toward a viewer in a direction perpendicular to the plane of the waveguide; wherein at least one of the optical structures (22, 28, 26) of the plurality of optical structures (22, 28, 26) has a profile in a direction perpendicular to the plane of the waveguide, wherein the profile varies along one or more directions parallel to the plane of the waveguide, such that the externally coupled stages are preferentially provided from the first main surface of the waveguide compared to the second main surface of the waveguide. A waveguide (1) for use in an augmented reality or virtual reality display, comprising: an output diffractive element comprising a plurality of optical structures (22, 28, 26) in a photonic crystal;a first major surface of the waveguide, and a second major surface of the waveguide, the first major surface separated in a direction perpendicular to a plane of the waveguide from the second major surface, wherein light propagates along the waveguide towards the output diffractive element by undergoing total internal reflection between the first and second major surfaces wherein the plurality of optical structures (22, 28, 26) are arranged in a plane of the waveguide in an array which is configured to receive light from an input direction and diffract the light into a plurality of orders, some of the orders being diffracted in the plane of the waveguide at an angle to the input direction to provide 2D expansion across the plane of the waveguide, and other orders being out-coupled in a direction perpendicular to the plane of the waveguide towards a viewer;wherein at least one of the optical structures (22, 28, 26) of the plurality of optical structures (22, 28, 26) has a profile in a direction that is perpendicular to the plane of the waveguide, wherein the profile varies along one or more directions parallel to the plane of the waveguide, such that the out-coupled orders are provided preferentially from the first major surface of the waveguide compared to the second major surface of the waveguide.;

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