To provide a compound that is capable of improving the function of an organic material.

The present technology provides a compound represented by the following general formula (1).

##STR00001##

In the general formula (1), X.sup.1 represents an oxygen atom, a nitrogen atom, a phosphorus atom, a carbon atom, or a silicon atom.

Y.sup.1 and Y.sup.2 each represent a benzene ring or a naphthalene ring, and both Y.sup.1 and Y.sup.2 do not represent benzene rings.

R.sup.1 to R.sup.3 each represent a hydrogen or a substituent group represented by *—Z.sup.1(R.sup.4).sub.d (* represents a bonding site).

Z.sup.1 represents a single bond, a saturated hydrocarbon group having a valence of 2 or higher, or an unsaturated hydrocarbon group having a valence of 2 or higher, the saturated hydrocarbon group or the unsaturated hydrocarbon group optionally having an ether bond and/or a thioether bond.

R.sup.4 represents a hydrogen or a polymerizable substituent group.

Provided is a photopolymer composition for hologram recording comprising: a polymer matrix or a precursor thereof; a dye including a compound of the following Chemical Formula 1; a photoreactive monomer; and a photoinitiator, ##STR00001##

Techniques disclosed herein relate to modifying refractive index modulation in a holographic optical element, such as a holographic grating. According to certain embodiments, a holographic optical element or apodized grating includes a polymer layer comprising a first region characterized by a first refractive index and a second region characterized by a second refractive index. The holographic optical element or apodized grating includes a plurality of nanoparticles dispersed in the polymer layer. The nanoparticles have a higher concentration in either the first region or the second region. In some embodiments, the nanoparticles may be configured to increase the refractive index modulation. In some embodiments, the nanoparticles may be configured to apodize the grating by decreasing the refractive index modulation proximate to sides of the grating. The refractive index may be modulated by applying a monomer reservoir buffer layer to the polymer layer, either before or after hologram fabrication.

The apertures typically used for hologram recording create unwanted secondary holograms by diffracting light. Aperture-free hologram recording eliminates these unwanted secondary holograms. Aperture-free hologram recording includes applying a mask to the holographic recording medium. The mask controls the size of the recorded hologram like an aperture but does not create unwanted secondary holograms. Hologram fringes are only present in the desired recording area and a thin boundary region. The mask may be present during recording, or the mask may be used to pre-bleach the holographic recording medium. Pre-bleaching the holographic recording medium renders a portion of the holographic recording medium insensitive to light, the hologram is recorded in the light-sensitive portions of the holographic recording medium.

To provide a photosensitive composition capable of further improving diffraction characteristics.

The present technology provides a photosensitive composition including: at least a compound represented by the following general formula (1); a binder resin; and a photoinitiator.

##STR00001##

In the general formula (1), X.sup.1 represents an oxygen atom, a nitrogen atom, a phosphorus atom, a caron atom, or a silicon atom.

Y.sup.1 and Y.sup.2 each represent a benzene ring or a naphthalene ring, and both Y.sup.1 and Y.sup.2 do not represent benzene rings.

R.sup.1 to R.sup.3 each represent a hydrogen or a substituent group represented by *—Z.sup.1(R.sup.4).sub.d (* represents a bonding site).

Z.sup.1 represents a single bond, a saturated hydrocarbon group having a valence of 2 or higher, or an unsaturated hydrocarbon group having a valence of 2 or higher, and the saturated hydrocarbon group or the unsaturated hydrocarbon group may have an ether bond and/or a thioether bond.

R.sup.4 represents a hydrogen or a polymerizable substituent group.

A holographic recording medium composition contains an isocyanate group-containing compound (component (a-1)), an isocyanate-reactive functional group-containing compound (component (b-1)), a polymerizable monomer (component (c-1)), a photopolymerization initiator (component (d-1)), and a stable nitroxyl radical group-containing compound (component (e-1)). A ratio of the total weight of a propylene glycol unit and a tetramethylene glycol unit that are contained in the component (b-1) to the total weight of the component (a-1) and the component (b-1) is 30% or less.

Recording a volume Bragg grating is effectuated by a recording medium formed from a matrix polymer precursor including a controlled radical reactive group, a photoactive base monomer, and a photoinitiator system more reactive with the photoactive base monomer 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 from the matrix polymer precursor. Exposure to the excitation source through a pattern causes the photoinitiator to polymerize the base monomer, forming a latent grating of the Bragg grating. The latent grating has bright and dark fringes determined by the pattern. The concentration of polymerized base polymer is higher in the bright fringes than in the dark fringes. The exposing causes a portion of the matrix to diffuse into the dark fringes. The support matrix has a lower refractive index than the polymerized photoactive base monomer.

Improvements to gratings for use in waveguides and methods of producing them are described herein. Deep surface relief gratings (SRGs) may offer many advantages over conventional SRGs, an important one being a higher S-diffraction efficiency. In one embodiment, deep SRGs can be implemented as polymer surface relief gratings or evacuated periodic structures (EPSs). EPSs can be formed by first recording a holographic polymer dispersed liquid crystal (HPDLC) periodic structure. Removing the liquid crystal from the cured periodic structure provides a polymer surface relief grating. Polymer surface relief gratings have many applications including for use in waveguide-based displays.

Improvements to gratings for use in waveguides and methods of producing them are described herein. Deep surface relief gratings (SRGs) may offer many advantages over conventional SRGs, an important one being a higher S-diffraction efficiency. In one embodiment, deep SRGs can be implemented as polymer surface relief gratings or evacuated periodic structures (EPSs). EPSs can be formed by first recording a holographic polymer dispersed liquid crystal (HPDLC) periodic structure. Removing the liquid crystal from the cured periodic structure provides a polymer surface relief grating. Polymer surface relief gratings have many applications including for use in waveguide-based displays.

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.