Abstract: According to one embodiment, an optical recording head device includes a light source which outputs such a relaxation oscillation optical pulse that a full width at half maximum of a single pulse is 820 ps or less, a driving unit for driving the light source, an objective lens which converges emission light from the light source on a recording layer of a recording medium, and captures reflective light which is reflected by the recording layer of the recording medium, a distribution unit, placed between the light source and the objective lens, for distributing incident light, and a photodetection unit for receiving via the distribution unit the reflective light which is reflected by the recording layer of the recording medium, wherein a resonator length of the light source is 6560 ?m or less.

Abstract: A Phase-change optical recording media includes a recording film that causes reversible phase-change between a crystalline phase and an amorphous phase on irradiation with light, and an interface film formed in contact with at least one surface of the recording film and containing Hf (hafnium), O (oxygen) and N (nitrogen).

Abstract: A phase change recording medium comprising an as-deposited first recording layer configured to undergo a reversible phase change between an amorphous state and a crystalline state due to light irradiation and thereby change an optical characteristic. The as-deposited first recording layer includes a plurality of fine nuclei having an average size of 0.5 nm to 4 nm in the amorphous state.

Abstract: An optical disc is provided which realizes desired optical properties, which has a transmissive reflection layer causing no deformation and the like of minute convex pits, and which can realize superior reproduction properties even when high density recording is performed. The above optical disc has at least three information layers independent with respect to a light incident surface, and a reflection layer formed on an information layer other than the layers most close to and most far from the light incident surface has a thickness of 5 to 20 nm and has a refractive index of 3.0 or more and an extinction coefficient of 0.6 or less with respect to the wavelength of incident laser light. This reflection layer is preferably composed of at least one material selected from the group consisting of Si, a SiCr alloy, a SiNb alloy, a SiW alloy, and SiC.

Abstract: A phase-change optical recording medium has a first information layer including a phase-change optical recording film arranged in a position close to the light incident side, a second information layer including another phase-change optical recording film arranged in a position remote from the light incident side and an interlayer separating film arranged between the first information layer and the second information layer, in which at least one of the first information layer and the second information layer includes a noise reduction film in contact with the interlayer separating film. The noise reduction film is formed of SiOx (1?x?2) or SiOC.

Abstract: A phase-change optical recording medium includes a phase-change optical recording film that permits reversible phase change between a crystalline phase and an amorphous phase upon irradiation with light, and an interface film formed of hafnium oxide, or a mixture of hafnium oxide and at least one oxide selected from the group consisting of cerium oxide, titanium oxide and zirconium oxide, and formed in contact with at least one surface of the phase-change optical recording film.

Abstract: According to one embodiment, a single-sided, multilayered optical disc which performs recording and playback when irradiated with a laser beam having a predetermined wavelength, and has at least two recording layers that are independent of each other with respect to the light incident surface, a reflecting layer farthest from the light incident surface contains an Ag alloy, and has a light absorbance of 20% (inclusive) to 50% (inclusive) to a laser beam and/or a thermal conductivity of 50 (inclusive) to 250 (inclusive) W/m·K.

Abstract: A phase-change optical recording medium has a phase-change recording film to which recording and erasure can be reversibly performed by irradiation with light, and at least one dielectric film formed of a SiOC film containing Si, O and C, and having a carbon concentration within a range of between 0.1 and 30 atomic %.

Abstract: A phase-change optical recording medium has a phase-change recording film to which recording and erasure can be reversibly performed by irradiation with light, and at least one dielectric film formed of a SiOC film containing Si, O and C, and having a carbon concentration within a range of between 0.1 and 30 atomic %.

Abstract: According to one embodiment, in a phase-change optical disk which has a substrate and a stacked structure including an interference film, a phase-change recording film, an interface film, and a reflecting film and which enables the recording film to be recorded into or erased from reversibly with light, the elements constituting the recording film have a segregation or a concentration distribution in the direction of the thickness of the recording film from a region in contact with the phase-change recording film, or in the in-plane direction (or in the direction perpendicular to the thickness) of the recording film.

Abstract: According to one embodiment, there is provided an optical disk including a substrate layer having a refractive index of 1.50 to 1.70 and a thickness X (?m) equal to or greater than f (n)?13 ?m, a first information layer formed on the substrate layer, an adhesive layer formed on the first information layer and having a thickness Y (?m) equal to or greater than 20 ?m, and a second information layer formed on the adhesive layer, wherein X+Y?f (n)+30 ?m and f(n)<X+Y/2 are satisfied and f (n) is given by the formula f (n)=(A1×n3)(n2+A2)/(n2?1)(n2+A3)×1000 (?m), where “n” is a refractive index of the substrate layer, A1 is 0.26200, A2 is ?0.32400, and A3 is 0.00595.

Abstract: According to one embodiment, in a phase change optical disk which has a substrate and a multi-layered including an interference film, phase change recording film, interface film, and reflecting film, and in which information is reversibly recorded in or erased from the recording film by using light, an element (e.g., Ge or Te) forming the phase change recording film has segregation or a concentration distribution in the thickness direction of the recording film from a portion in contact with the phase change recording film.

Abstract: An optical recording medium includes an optical recording layer, a separating layer formed on a reproducing light incident side of the optical recording layer, and a phase-change reproducing layer formed on the reproducing light incident side of the separating layer, absorbance of which phase-change reproducing layer is changed depending on whether a state of the optical recording layer is a recording mark or a space. A transfer portion to which a state of the optical recording layer is transferred is formed in a portion having high absorbance of the phase-change reproducing layer by irradiation with reproducing light, while a portion of the phase-change reproducing layer other than the transfer portion is kept in a state optically differing from the transfer portion.

Abstract: A phase-change optical recording medium has a recording film that brings about reversible phase-change between a crystalline phase and an amorphous phase upon irradiation with light and an interface film formed in contact with at least one surface of the recording film and comprising hafnium (Hf), silicon (Si), oxygen (O) and carbon (C).

Abstract: A phase-change optical recording medium has a recording film that brings about reversible phase-change between a crystalline phase and an amorphous phase upon irradiation with light and an interface film formed in contact with at least one surface of the recording film and comprising hafnium (Hf), silicon (Si), oxygen (O) and carbon (C).

Abstract: In a single-sided, recordable/rewritable phase change optical recording medium having one or more layers, an interface layer adjacent to a phase change optical recording film contains at least Zr (zirconium), O (oxygen), and N (nitrogen), and further contains one or both of Y (yttrium) and Nb (niobium).

Abstract: According to one embodiment, an information storage medium includes a light incident surface from which a recording/playback light beam enters, a reflecting layer which reflects the light beam entering from the light incident surface, a recording layer which is arranged between the light incident surface and the reflecting layer, and a playback signal emphasizing layer which is arranged between the recording layer and the reflecting layer, and used to emphasize a playback signal containing a reflectance change component generated by a recording mark formed on the recording layer.

Abstract: A phase-change optical recording medium has a recording film that brings about reversible phase-change between a crystalline phase and an amorphous phase upon irradiation with light and an interface film formed in contact with at least one surface of the recording film and comprising hafnium (Hf), silicon (Si), oxygen (O) and carbon (C).

Abstract: A phase-change optical recording medium has a phase-change recording film to which recording and erasure can be reversibly performed by irradiation with light, and at least one dielectric film formed of a SiOC film containing Si, O and C, and having a carbon concentration within a range of between 0.1 and 30 atomic %.

Abstract: A phase-change optical recording medium has a phase-change recording film to which recording and erasure can be reversibly performed by irradiation with light, and at least one dielectric film formed of a SiOC film containing Si, O and C, and having a carbon concentration within a range of between 0.1 and 30 atomic %.