Abstract: Conventionally, in making a double-sided optical disc by attaching recording substrates to each other via an ultraviolet curable adhesive layer, there was a problem that the ultraviolet curable adhesive layer was slow to cure. It is thought that this is because the out gases leached from the recording substrate disturbed the cure reaction of the adhesive layer. In contrast, in the optical disc of the present disclosure, it is possible to cure the adhesive layer in a short time in attaching the recording substrates to each other via the ultraviolet curable adhesive layer, by providing a gas barrier layer at an attachment surface of a substrate to inhibit out gases from leaching from the substrate to the ultraviolet curable adhesive layer.

Abstract: The subject matter of the invention is to provide an optical recording medium with improvements in repeated overwrite characteristics, write power margin, archival stability and the like. The invention provides an optical recording medium having a semi-transparent layer mainly comprising Ag, a first protective layer comprising a dielectric, a phase-change recording layer comprising an alloy mainly comprising SbxTe1−x (0.7<x≦0.9), a second protective layer comprising a dielectric, and a metallic reflective layer in this order, wherein the medium further has an interdiffusion-protection layer between the semi-transparent layer and the first protective layer where the first protective layer comprises a sulfur-containing dielectric, and the medium has a higher reflectance to light incident on the semi-transparent layer side with the recording layer being in an amorphous state than in a crystalline state.

Abstract: The subject matter of the invention is to provide an optical recording medium with improvements in repeated overwrite characteristics, write power margin, archival stability and the like.