Abstract: An optical data carrier is presented. The data carrier comprises at least one recording layer, at least one non-recording layer, and at least one reflective interface. The recording layer is made of a material having a fluorescent property variable on occurrence of multi-photon absorption resulted from an optical beam, and has a thickness for recording therein data in the form of a three-dimensional pattern of spaced-apart recording regions arranged in a plurality of recording planes. The at least one non-recording layer interfaces with the recording layer on, respectively, at least one of upper and lower surfaces of the recording layer The non-recording layer has a fluorescent property different from that of the recording layer, and has a predetermined thickness selected to be equal or larger than a focal depth of an optical system producing the optical beam incidence onto the data carrier. The at least one reflective interface comprises at least one reference layer having a reflecting property.

Abstract: An optical data carrier is presented. The data carrier comprises: at least one recording layer composed of a material having a fluorescent property variable on occurrence of multi-photon absorption resulting from an optical beam, said recording layer having a thickness for forming a plurality of recording planes therein; at least one non-recording layer formed on at least one of upper and lower surfaces of said recording layer and differing in fluorescent property from said recording layer; and at least one reference layer having a reflecting surface being an interface between the recording layer and the non-recording layer.