An optical assembly may include a waveguide and a Bragg grating configured to couple light into or out of the waveguide. The Bragg grating may include a plurality of layer pairs, wherein at least one layer pair comprises a first material having a first refractive index and a second layer having a second refractive index, and wherein properties of the Bragg grating are selected so that the Bragg grating exhibits a substantially similar diffractive efficiency and diffraction angle for light of at least two colors.

A backlight module, including: a first base, a mini light-emitting diode chip array, an encapsulation layer covering the mini light-emitting diode chip array and a superlens array sequentially arranged on a first substrate; and a second base, a wire grate array and a prism structure sequentially arranged on a second substrate. The superlens array, the wire grate array and the prism structure include a plurality of superlenses, a plurality of wire grates and a plurality of prism groups, respectively. The second base is a glass base, orthographic projections of the plurality of wire grates on the first base at least partially overlap with the orthographic projections of the plurality of superlenses on the first base, respectively, and orthographic projections of the plurality of prism groups on the first base are located between the orthographic projections of two adjacent wire grates on the first base, respectively.

In various embodiments, wavelength beam combining laser systems incorporate optical cross-coupling mitigation systems and/or engineered partially reflective output couplers in order to reduce or substantially eliminate unwanted back-reflection of stray light.

A grating coupler with a wafer bonded configuration includes: a substrate; an oxide layer disposed on the substrate; a silicon nitride layer disposed above the oxide layer; a first silicon layer disposed above the silicon nitride layer; a second silicon layer disposed above the first silicon layer; and a bi-layer grating disposed above the silicon nitride layer. The bi-layer grating includes (i) a first etched layer of the first silicon layer and (ii) a second etched layer of the second silicon layer.

A system includes a diffractive optical element configured to receive a first beam and a second beam interfering with one another to generate a first interference pattern. The diffractive optical element is also configured to forwardly diffract the first beam and the second beam to output a third beam and a fourth beam. The third beam and the fourth beam interfere with one another to generate a second interference pattern. The system also includes a detector configured to detect the second interference pattern.

This document relates to an optical device using waveguide that can enable propagation of large field of view images by use of metasurfaces, without the necessity of increasing the reflective index associated with the waveguide. An optical assembly can generate a compressed image corresponding to a wide field of view in order to ensure that the image can propagate through the waveguide according to TIR limits of the waveguide. The compressed image can be provided to a standard grating in-coupler, and can then be expanded by a metasurface out-coupler of the optical device to reproduce the wide field of view.

A light flux diameter expanding element includes a light guiding plate with a light input face and a light output face, and with a thickness of 0.2 mm to 0.8 mm; a diffraction grating on the input side; and a diffraction grating on the output side, and is provided so as to have the same grating period as that of the diffraction grating on the input side, in which a forming region of the diffraction grating on the input side is smaller than that of the output side, and a grating period of the diffraction grating on the input side is a period in which a small diffraction angle in diffraction angles of +1-st order diffracted light and −1-st order diffracted light, which are diffracted in the diffraction grating on the input side, in the light guiding plate becomes larger than a critical angle of the light guiding plate.

A grating coupler may be fabricated by exposing a photopolymer layer to grating forming light for forming periodic refractive index variations in the photopolymer layer. The photopolymer layer may be exposed to apodization light for reducing an amplitude of the periodic refractive index variations in a spatially-selective manner. The apodization may also be achieved or facilitated by subjecting outer surface(s) of the photopolymer layer to a chemically reactive agent that causes the refractive index contrast to be reduced near the surface(s) of application. The apodized refractive index profile of the gratings facilitates the reduction of optical crosstalk between different gratings of the grating coupler.

An optical system is presented for use in a near-eye mixed reality system. The system comprises a relay system defining an eyebox of the optical system, said relay system being configured and operable to relay a virtual image light field from a light-engine onto an eye pupil plane while combining said virtual image with real-world light field. The relay system is configured as a free space relay system configured for free space propagation of said virtual image light field being relayed, said free space relay system comprising at least one off-axis 4f-system. Each of said at least one off-axis 4f-system comprises at least one lens formed from at least one resonance-domain surface relief diffractive optical element (SRDOE) operable for combining said virtual image light field with the real-world light field, said at least one SRDOE being configured with a predetermined global surface relief pattern characterized by global variation of at least some of pattern parameters across said SRDOE.

A compressive/transform imager comprising a lens array positioned above input ports for collecting light into the input ports, waveguides routing the light from the input port to waveguide mixing regions (e.g. multi-mode interference couplers), and detectors for receiving outputs of the waveguide mixing regions.