A multilayer optical information recording disk comprising a plurality of recording layers and intermediate layers provided between the plurality of recording layers, and a method for manufacturing the same are provided. At least one of two intermediate layers disposed adjacent to respective sides of one recording layer is made of adhesive. Each of the recording layers includes a polymer binder and a dye dispersed in the polymer binder or includes a polymer to which a dye is bonded. Each recording layer is configured such that the dye absorbs a recording beam and generates heat which deforms the recording layer, causing an interface between the recording layer and the intermediate layer made of adhesive to have a protrusive shape protruding into the intermediate layer, thereby recording information thereat. The interface between the recording layer and the recording layer made of adhesive has a groove for track-following servo control.

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.

Provided is a photopolymer composition that may exhibit low volume shrinkage during holographic recording and may prevent a photosensitive dye from remaining unbleached after holographic recording.

A data protector according to an embodiment of the present disclosure includes: a data layer configured to record confidential information as a visible image; and one or a plurality of cover layers disposed at least one of above or below the data layer and configured to transition between a color-developed state and a decolored state in a visible wavelength region.