Abstract: A guide-layer separated optical disk which includes a guide layer having a guide structure whose tracking guide tracks are divided into areas by discontinuous portions, the areas each having concentric guide tracks of arc shape at a regular track pitch, the guide tracks in adjoining two of the areas across one of the discontinuous portions deviating from each other in a radial direction of the disk by ¼ the track pitch. An optical disk drive apparatus and a tracking control method in which a servo optical system switches the tracking center of the irradiation spot of a first laser beam between on the guide tracks and in between the guide tracks alternately each time the irradiation spot passes two of the discontinuous portions.

Abstract: The optical storage medium comprises a substrate layer, a data layer, and a nonlinear layer with a super-resolution structure disposed on the data layer, wherein pits and lands having a size above a diffraction limit of a pickup for reading of the data establish a first and a second level of the data layer, and pits and lands having a size below the diffraction limit of the pickup are arranged on a further level of the data layer. In a preferred embodiment, pits having a size below the diffraction limit are arranged on a third level and lands having a size below the diffraction limit are arranged on a fourth level of the data layer. The optical storage medium is in particular a read-only optical disc comprising a phase-change material, for example AgInSbTe, for providing the super-resolution effect.

Abstract: An optical data carrier is presented comprising first and second recordable media located in at least one first portion and at least one second portion of the data carrier, respectively. These first and second recordable media differ from each other in a storage capacity and a data recording rate.