Described herein are novel azo-benzene type chromophores. The chromophores are useful in photochromic compositions comprising a polymer matrix and a chromophore, wherein the chromophore is a novel azo-benzene type structure. The photochromic composition is photoresponsive upon irradiation by at least one wavelength of laser light across the visible light spectrum. Photochromic devices which comprise the novel azo-benzene type chromophore compound show significantly higher photoinduced birefringence, higher diffraction efficiency, and brighter images than devices that comprise well known azo-benzene chromophores. The photochromic composition may include a liquid crystal.

Described herein are novel azo-benzene type chromophores. The chromophores are useful in photochromic compositions comprising a polymer matrix and a chromophore, wherein the chromophore is a novel azo-benzene type structure. The photochromic composition is photoresponsive upon irradiation by at least one wavelength of laser light across the visible light spectrum. Photochromic devices which comprise the novel azo-benzene type chromophore compound show significantly higher photoinduced birefringence, higher diffraction efficiency, and brighter images than devices that comprise well known azo-benzene chromophores. The photochromic composition may include a liquid crystal.

The present invention is to provide: a photosensitive composition for volume hologram recording and a photosensitive substrate for volume hologram recording, which provide increased sensitivity during hologram recording and a high refractive index modulation amount, and which do not inhibit the decolorization of the sensitizing dye; and a volume hologram recorded medium which provides high-luminance hologram images with increased productivity. Disclosed is a photosensitive composition for volume hologram recording, comprising: a photopolymerizable monomer, a photopolymerization initiator, a sensitizing dye for sensitizing the photopolymerization initiator, a binder resin, and a thiol group-containing compound, wherein the photopolymerizable monomer contains a photoradically polymerizable monomer and a photocationically polymerizable monomer; wherein the thiol group-containing compound is a chain transfer agent for the photoradically polymerizable monomer and is a polyfunctional secondary thiol compound having two or more secondary thiol groups per molecule; and wherein the content of the thiol group-containing compound is 1.5 to 30 parts by mass with respect to 100 parts by mass of the photoradically polymerizable monomer.

The present invention is to provide: a photosensitive composition for volume hologram recording and a photosensitive substrate for volume hologram recording, which provide increased sensitivity during hologram recording and a high refractive index modulation amount, and which do not inhibit the decolorization of the sensitizing dye; and a volume hologram recorded medium which provides high-luminance hologram images with increased productivity. Disclosed is a photosensitive composition for volume hologram recording, comprising: a photopolymerizable monomer, a photopolymerization initiator, a sensitizing dye for sensitizing the photopolymerization initiator, a binder resin, and a thiol group-containing compound, wherein the photopolymerizable monomer contains a photoradically polymerizable monomer and a photocationically polymerizable monomer; wherein the thiol group-containing compound is a chain transfer agent for the photoradically polymerizable monomer and is a polyfunctional secondary thiol compound having two or more secondary thiol groups per molecule; and wherein the content of the thiol group-containing compound is 1.5 to 30 parts by mass with respect to 100 parts by mass of the photoradically polymerizable monomer.

A recording medium according to the present disclosure includes a recording layer containing an organic compound having a non-linear optical absorption characteristic. The molar extinction coefficient of the organic compound against light having a wavelength of longer than or equal to 400 nm and shorter than or equal to 405 nm is greater than or equal to 90 mol.sup.1.Math.L.Math.cm.sup.1. In a transient absorption spectrum of the organic compound, an absorbance change Abs at a wavelength of longer than or equal to 400 nm and shorter than or equal to 405 nm is a positive value.

A recording medium according to the present disclosure includes a recording layer containing an organic compound having a non-linear optical absorption characteristic. The molar extinction coefficient of the organic compound against light having a wavelength of longer than or equal to 400 nm and shorter than or equal to 405 nm is greater than or equal to 90 mol.sup.1.Math.L.Math.cm.sup.1. In a transient absorption spectrum of the organic compound, an absorbance change Abs at a wavelength of longer than or equal to 400 nm and shorter than or equal to 405 nm is a positive value.

An optical recording medium of an aspect of the present disclosure includes a recording layer and a dielectric layer positioned on the recording layer and containing a porous organic structural body. A method for recording information of an aspect of the present disclosure includes preparing a light source emitting light having a wavelength of longer than or equal to 390 nm and shorter than or equal to 420 nm and focusing the light from the light source and applying the light to the recording layer of the optical recording medium.

Described herein are novel azo-benzene type chromophores. The chromophores are useful in photochromic compositions comprising a polymer matrix and a chromophore, wherein the chromophore is a novel azo-benzene type structure. The photochromic composition is photoresponsive upon irradiation by at least one wavelength of laser light across the visible light spectrum. Photochromic devices which comprise the novel azo-benzene type chromophore compound show significantly higher photoinduced birefringence, higher diffraction efficiency, and brighter images than devices that comprise well known azo-benzene chromophores. The photochromic composition may include a liquid crystal.

The present disclosure relates to a hologram recording medium, a preparation method thereof, and an optical element including the same. The hologram recording medium can have excellent optical recording characteristics and low haze by controlling an element ratio of fluorine on the surface of the photopolymer layer to a specific range, and can provide an optical element with excellent visibility.