A method to form a three-dimensional photonic crystal template with a gradient structure involves irradiating a photoresist composition of a thickness of at least 15 μm from at least four laser beams to yield a periodic patterned with a percolating matrix of mass in constructive volumes of a cured photoresist composition and destructive volumes of voids free of condensed matter where the proportion of constructive volume displays a gradient from the irradiated surface to the substrate after development. For a given light intensity, photoinitiator concentration in the photoresist composition, and a given thickness, by irradiating for a relatively short period, a three-dimensional photonic crystal template displaying a gradient having greater constructive volume proximal the air interface forms and a relatively long irradiation period results in a gradient having greater constructive volume proximal the substrate.

The present disclosure is to provide a photopolymer composition including a polymer matrix or a precursor thereof including a reaction product of a reactive isocyanate compound having a hydrogen bonding functional group capable of forming multiple hydrogen bonds and at least one isocyanate group, and a polyol having at least two hydroxyl groups; a photoreactive monomer; and a photoinitiator, a hologram recording medium produced from the photopolymer composition, an optical element including the photopolymer composition and a holographic recording method using the photopolymer composition.

A photoreactive liquid crystal composition containing (A) a photoreactive polymer liquid crystal which includes a photoreactive side chain in which at least one type of reaction selected from (A-1) photocrosslinking and (A-2) photoisomerization occurs, and (B) a low molecular weight liquid crystal. An optical element or display element is formed having a liquid crystal cell including the photoreactive liquid crystal composition.

The present invention provides a composition for hologram recording, a hologram recording medium and a hologram that are capable of realizing excellent diffraction characteristics and an optical device and an optical member using same. The present invention is capable of providing a composition for hologram recording containing at least a radical polymerizable monomer and a matrix resin, in which a cross-sectional observation image at the time of observing a hologram recording film by atomic force microscopy (AFM) has a diffraction grating structure indicating that there is a material density difference that can be observed by the AFM.

Provided herein are compositions suitable for recording holograms containing thiol and/or thioether functionality, and optionally including additional allyl and/or propargyl functional groups. These monomers can be used to synthesize holographic poly-mers having high Lin values. Also provided herein are methods of making holographic polymers and methods recording holograms using these polymers.

An interference structure having a nanovoided hologram material is described. The nanovoided hologram material may have an index of refraction difference of approximately 0.4. The interference structure may include about 10% to 90% nanovoids by volume. The interference structure may be formed using a mixture of a monomer, an initiator, and solvent. The mixture may be disposed on a substrate and irradiated with two sources of light spaced apart from each other and shining on the same region of the mixture to generate an interference pattern in the mixture, leading to the selective polymerization of regions of the mixture where there is constructive interference of light. Various other devices, methods, and systems are also disclosed.

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 forming a security device includes: a holographic image layer, diffusion element, and barrier layer. A region of the barrier layer includes a heat-transformable material. The method further includes selectively applying heat at a plurality of positions within the region of the barrier layer, in accordance with a predetermined pattern, so as to modify the heat-transformable material such that the region of the barrier layer is selectively rendered passable to the diffusible substance at each of the plurality of positions, thereby permitting diffusion of the diffusible substance between the regions of the diffusion element and the holographic image layer such that, at a plurality of positions within the region of the holographic image layer and corresponding to the predetermined pattern, the volume hologram is dimensionally modified so as to become viewable in a second observable colour, different from the first observable colour.

A holographic recording medium composition comprising component (e): a compound having an isocyanate group or an isocyanate-reactive functional group and further having a nitroxyl radical group, wherein component (e) contains component (e-1) below: component (e-1): a compound having a heterobicyclic ring structure or a heterotricyclic ring structure, the heterobicyclic ring structure or the heterotricyclic ring structure being obtained by replacing a carbon atom in a bicyclic ring structure or a tricyclic ring structure by the nitroxyl radical group.

Systems and methods for fabricating optical elements in accordance with various embodiments of the invention are illustrated. One embodiment includes a method for fabricating an optical element, the method including providing a first optical substrate, depositing a first layer of a first optical recording material onto the first optical substrate, applying an optical exposure process to the first layer to form a first optical structure, temporarily erasing the first optical structure, depositing a second layer of a second optical recording material, and applying an optical exposure process to the second layer to form a second optical structure, wherein the optical exposure process includes using at least one light beam traversing the first layer.