Configurations for a diffraction grating design and methods thereof are disclosed. The diffraction grating system can include an input waveguide located at a first location on or near a Rowland circle and multiple output waveguides located at a second and third location on or near the Rowland circle. The input waveguide may be located between the output waveguides and this configuration of input and output waveguides can reduce the footprint size of the device. In some examples, the optical component can function as a de-multiplexer. Additionally, the optical component may separate the input wavelength band into two output wavelength bands which are separated from one another by approximately 0.1 μm.

A diffractive optical element exerts a diffractive action on a display light that is emitted from a display unit. A folding mirror is provided on the opposite side of the diffractive optical element from the display unit to reflect the display light. The diffractive optical element includes a transmissive action part and a diffractive and reflective action part. The transmissive action part exerts a transmissive action to transmit therethrough the display light, which is incident from the display unit and is in a first polarization state, toward the folding mirror. The diffractive and reflective action part exerts a diffractive and reflective action to diffract and reflect the display light, which is reflected by the folding mirror and is in a second polarization state opposite to the first polarization state, toward the projection portion on an optical path.

A resonant waveguide grating includes a waveguiding layer and a plurality of subwavelength structures. The waveguiding layer, being in optical proximity to the plurality of subwavelength structures, is configured to guide at most ten wave-guided light modes. The plurality of subwavelength structures includes at least two adjacent grooves having a subwavelength distance between their groove centers being different than the subwavelength distance between the centers of two adjacent ridges. The plurality of subwavelength structures is configured to couple out of the waveguiding layer resonantly by diffraction, an outcoupled fraction of an incoupled portion of incident light. The outcoupled fraction is a diffracted part of an incident light beam. A diffractive optical combiner and a diffractive optical coupler, both include the resonant waveguide grating of the invention. A near-eye display apparatus includes at least the resonant waveguide grating of the invention.

A metallic grating is formed to include a substrate; a plurality of high aspect ratio trenches disposed in the substrate such that the high aspect ratio trenches are spaced apart from one another by a field surface of the substrate; a metallic superconformal filling formed and disposed in the high aspect ratio trenches; and a grating including a spatial arrangement of the high aspect ratio trenches that are filled with the metallic superconformal filling such that the metallic superconformal filling is void-free, and the high aspect ratio trenches are bottom-up filled with the metallic superconformal filling, wherein a height of the metallic superconformal filling is less than or equal to the height of the high aspect ratio trenches.

A structural color developing member includes: a base material including a surface, at least a portion of which is provided with a fine ridged/grooved structure formed at a constant arrangement pitch, the base material developing a structural color by the fine ridged/grooved structure; and a color developing layer layered on a surface of the fine ridged/grooved structure. The color development from the color developing layer is a hue included in color development of the structural color, and a region of the structural color developing member in which the fine ridged/grooved structure and the color developing layer are provided is visually recognizable in a single hue. Instead of the color developing layer, a polarized reflection layer may be provided.

An electronic device may include a housing and a display mounted to the housing. The housing may have a rear wall, a front wall that forms a display cover layer, and sidewalls. A coating may be formed on a portion of the housing. The coating may include a diffractive layer having a textured surface that diffracts incoming light to form at least part of a spectral rainbow on an outer surface of the housing. The textured surface may have pits and bumps in any suitable shape and pattern. The coating may include a thin-film interference layer that increases an intensity of the spectral rainbow. The thin-film interference layer may be interposed between an ink layer and the diffractive layer. The diffractive layer may be a reflective diffractive layer that reflects ambient light or a transmissive diffractive layer that transmits light from a light source in the electronic device.

An image display apparatus according to an embodiment of the present technology includes a first screen and a second screen. The first screen includes an image surface on which an object image is formed, the first screen obliquely projecting the object image from the image surface. The second screen includes an incident surface that is arranged parallel to the image surface and on which image light of the object image is incident, the second screen diffracting the image light in an exit direction different from a specular-reflection direction that corresponds to a direction of incidence of the image light on the incident surface, the second screen forming a virtual image parallel to the object image.

A color display of an embodiment includes: an embossed layer; a high refractive index layer; and a protective layer, laminated in this order, wherein the high refractive index layer has a highest refractive index among these layers, the embossed layer includes a first region having a periodic structure with a period at least smaller than a center wavelength of visible light, a plurality of the first regions, each having a strip shape, are connected to each other at their longitudinal end sides, the first regions being offset from each other in a direction perpendicular to a longitudinal direction of the strip shape, as viewed via a display surface, and a periodic direction of the periodic structure is parallel to the longitudinal direction.

A method for designing a freeform concave grating imaging spectrometer includes selecting a series of light rays incident from different positions of a slit as characteristic light rays. The coordinates and normal directions of characteristic data points at intersections of the characteristic light rays and a surface of a freeform concave grating are calculated. A freeform surface shape of the freeform concave grating is obtained by fitting, so that an initial structure is obtained. Then the initial structure is optimized.

Systems and method for eye tracking are provided. In some embodiments, the eye tracking system includes a light source configured to generate light and project the light toward an object in a field of view, a detector configured to receive reflected portions of the light from the field of view in order to image the object, and a combiner including a volume grating configured to direct light reflected from different points in a field of view to the light detector. The volume grating includes a plurality of portions along a first area and each of the portions comprising a unique k-vector that is dependent on a respective portion of the field of view.