Abstract: A multilayer optical recording medium including at least multiple information layers each having at least a phase change recording layer capable of recording information by laser irradiation and a reflection layer, wherein each information layer other than the innermost information layer as seen from a side of the laser irradiation has at least a lower protection layer, the phase change recording layer, an upper protection layer, the reflection layer and an optical transmission layer, the upper protection layer and the optical transmission layer in each information layer other than the innermost information layer as seen from the side of the laser irradiation are composed of an Sn oxide-containing material and a thickness of the upper protection layer in each information layer other than the innermost information layer as seen from the side of the laser irradiation is 2 nm to 15 nm is provided.

Abstract: A multilayer optical recording medium includes a plurality of interfacial surfaces that reflect an incident light beam, and neighboring ones of the interfacial surfaces has a spacer therebetween. When a light incident surface side is defined as an upper surface side, a different thickness layer unit including the spacers having different thicknesses arranged sequentially is disposed on the lowermost layer side, and the spacers each having a thickness different from the thickness of any one of the spacers arranged in the different thickness layer unit are sequentially arranged above the different thickness layer unit.

Abstract: A recording layer including a novel dye for a high density optical recording medium, employing short wavelength laser source with a wavelength not longer than 530 nm for recording high density information and reproduction/playback of the high density information recordings, is provided.