Abstract: An optical information carrier is presented. The information carrier comprises at least one active layer for recording/reading data in/from as a result of one- or multi-photon interaction; and at least one reference layer structure associated with said at least one active layer. The reference layer structure comprises at least one dielectric material and is different from that of the active layer in its optical properties with respect to one- or multi-photon interaction. Detection of light returned from the reference layer structure allows to control a process of focusing an optical beam onto an addressed recording plane in the active layer during at least one of the recording and reading processes.