Methods, systems, and devices for quantum key distribution (QKD) in passive optical networks (PONs) are described. A PON may be a point-to-multipoint system and may include a central node in communication with multiple remote nodes. In some cases, each remote node may include a QKD transmitter configured to generate a quantum pulse indicating a quantum key, a synchronization pulse generator configured to generate a timing indication of the quantum pulse, and filter configured to output the quantum pulse and the timing indication to the central node via an optical component (e.g., an optical splitter, a cyclic arrayed waveguide grating (AWG) router). The central node may receive the timing indications and quantum pulses from multiple remote nodes. Thus, the central node and remote nodes may be configured to communicate data encrypted using quantum keys.

A method of controlling a display apparatus includes: when the display apparatus is in a privacy display mode, obtaining, by an image processor, a plurality of frames of display images according to a frame of original image, transmitting, by the image processor, the plurality of frames of images to a display controller; controlling, by the display controller, the display panel to display the plurality of frames of display images in sequence within a display time of the frame of original image, and controlling, by the display controller, the grating panel to form light-transmitting regions and non-light-transmitting regions that are alternately arranged when the display panel displays each frame of display image, so as to limit an exit angle of light exiting from the display side of the display apparatus, the exit angle being within a range of a privacy viewing angle.

A display device includes a directional illuminator providing a light beam, a display panel downstream of a directional illuminator, for receiving and spatially modulating the light beam, and a beam redirecting module downstream of the display panel, for variably redirecting the spatially modulated light beam. Steering the illuminating light by the beam redirecting module enables one to steer the exit pupil of the display device to match the user's eye location(s).

Architecture and designs of modulating both amplitude and phase at the same time in spatial light modulation are described. According to one aspect of the present invention, light propagation is controlled in two different directions (e.g., 0 and 45 degrees) to perform both amplitude modulation and phase modulation at the same time in liquid crystals. In one embodiment, a mask is used to form a pattern, where the pattern includes an array of alignment cells or embossed microstructures, a first group of the cells are aligned in the first direction and a second group of the cells are aligned in the second direction. Depending on applications, two cells from the first group and the second group may correspond to a single pixel or two neighboring pixels, resulting in amplitude modulation and phase modulation within the pixel or within an array of pixels.

A display assembly includes: a display module including a plurality of pixel islands; and a plurality of lens arrays laminated at a light-exiting side of the display module. Each lens array includes a substrate, a cover plate, a first transparent electrode, a second transparent electrode, and a liquid crystal layer and a diffraction lens grating arranged between the first and second transparent electrodes. The diffraction lens grating includes a plurality of diffraction lens grating units corresponding to the plurality of pixel islands. A voltage is applied to each of the first and the second transparent electrodes in such a manner that a refractive index of a liquid crystal molecule in the liquid crystal layer is equal to or not equal to a refractive index of the diffraction lens grating.

A display device includes a directional illuminator providing a light beam, a display panel downstream of a directional illuminator, for receiving and spatially modulating the light beam, and a beam redirecting module downstream of the display panel, for variably redirecting the spatially modulated light beam. Steering the illuminating light by the beam redirecting module enables one to steer the exit pupil of the display device to match the user's eye location(s).

A window can comprise a first side and a second side substantially parallel to the first side. The window can comprise an optical grating operatively positioned with respect to one of the first side and the second side. The optical grating can be used to determine a temperature at or near the respective one of the first side and the second side.

A method of manufacturing a light guide substrate includes: providing a first base substrate; forming an interface protection layer on a side of the first base substrate; forming a grating structure layer at the side of the first base substrate where the interface protection layer has been formed; removing portions of the grating structure layer corresponding to the non-light extraction opening regions, so as to obtain a plurality of light extraction grating units in one-to-one correspondence with the plurality of light extraction opening regions; and removing portions of the interface protection layer corresponding to the non-light extraction opening regions. The first base substrate includes a plurality of light extraction opening regions and non-light extraction opening regions other than the plurality of light extraction opening regions.

An optical device for illuminating one or more portions of a spatial light modulator includes a waveguide, an array of tunable retarders, and a polarization selective optical element. A respective tunable retarder is optically coupled to receive light from the waveguide. The respective tunable retarder has a first state, which causes the respective tunable retarder to direct light having a first polarization in a first direction, and a second state, which causes the respective tunable retarder to direct light having a second polarization distinct from the first polarization in the first direction. The polarization selective optical element is located adjacent to the array of tunable retarders so that the light having the first polarization propagates from the polarization selective optical element in a second direction and the light having the second polarization propagates from the polarization selective optical element in a third direction distinct from the second direction.

The present application provides a color filter substrate, an array substrate and a display panel. A first dielectric grating layer in the color filter substrate is stacked with a first dielectric layer, and ridges and grooves are arranged at intervals periodically on one side of the first dielectric grating layer away from the first dielectric layer; a first polarizing layer in the color filter substrate is located in the grooves of the first dielectric grating layer; a second polarizing layer in the color filter substrate is located on the ridges of the first dielectric grating layer.