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.

A method of preparing a glazing, comprising: stacking a first glass sheet, a first interlayer, a photopolymer film, a second interlayer, and a second glass sheet to provide a lamination stack; &airing the lamination stack; autoclaving the lamination stack to provide a laminated glazing; applying a reactive light to the photopolymer film in the laminated glazing, wherein reactive light is applied to the laminated glazing through a master holographic film; and bleaching the laminated glazing such that the photopolymer film is no longer reactive to light exposure.

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.

A method includes providing a radiation with a predetermined intensity profile. The method also includes providing a photo-sensitive medium layer including a mixture of a photo-sensitive material and an absorbing additive. The absorbing additive has a predetermined non-uniform distribution in at least one of a direction within a film plane or a thickness direction of the photo-sensitive medium layer. The predetermined non-uniform distribution of the absorbing additive is configured to result in a predetermined non-uniform absorption of the radiation. The method also includes exposing the photo-sensitive medium layer to the radiation to form a polymer film. The optical film includes at least one predetermined birefringence variation in at least one of a direction within a film plane or a thickness direction of the polymer film.

An illumination unit emits an illumination light to a specimen. An image sensor includes multiple pixels arranged in a two-dimensional manner. The image sensor captures an image of the intensity distribution of an interference pattern formed due to the illumination light that has interacted with the specimen, and outputs image data. A defect information acquisition unit acquires defect position information that indicates the positions of defective pixels of the image sensor. A processing unit reconstructs a subject image that represents the specimen based on the image data and the defect position information.

A method for making an optical grating having a non-uniform refractive index profile along a direction substantially perpendicular to a plane defined by the optical grating includes placing a layer of photopolymerization material having a first surface and a second surface that is opposite to the first surface between a first material transfer layer and a second material transfer layer so that the first surface of the layer of photopolymerization material is in contact with the first material transfer layer and the second surface of the layer of photopolymerization material is in contact with the second material transfer layer to allow material transfer between the layer of photopolymerization material and the first and second material transfer layers by diffusion.

An optical coupler includes a plurality of volume gratings in a substrate. The gratings include an array of fringes extending along length and thickness dimensions of the substrate. A difference between a refractive index of the fringes and a refractive index of the substrate depends on a depth coordinate along the thickness dimension of the substrate. A dependence of the difference on the depth coordinate has a bell-shaped function which suppresses ghost image formation due to optical crosstalk between gratings of neighboring spatial pitches.

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.

Methods of recording a volume Bragg grating are provided. A recording medium is formed from a matrix polymer precursor, an inimer comprising a polymerizable functional group and a controlled radical reactive group, a first photoinitiator system that is more reactive with the polymerizable functional group than the controlled radical reactive group in the presence of an excitation source, and a photoredox catalyst. The medium is cured thereby forming a support matrix. The medium is exposed to light causing the first photoinitiator system to react with the polymerizable functional group and to polymerize the inimer within the support matrix thus forming a latent grating image of the volume Bragg grating within the medium. The latent grating image comprises a plurality of bright fringes and a plurality of dark fringes. A concentration of polymerized inimer is higher in the plurality of bright fringes than in the plurality of dark fringes.

A liquid crystal laminate includes a substrate including a first diffraction surface and a second base material surface and having optical transparency, a metal layer located on a part of the first diffraction layer, an adhesion layer located on a part of the second base material layer and made of a photocured resin, and liquid crystal layer located on a surface of the adhesion layer at a side opposite to the contact surface of the substrate.